⎇ⓥ⺖㗴ฬ㧦FEL ߦࠃࠆᣂ⚛᧚ߩ㐿⊒⎇ⓥઍ⴫⠪㧦ጊᧄ ኡ(ᣣᧄᄢቇℂᎿቇㇱ㔚ሶᖱႎᎿቇ⑼)‫⎇ޣ‬ⓥ⋡⊛‫ޤ‬ ᧄ⎇ⓥߩ⋡⊛ߪ⥄↱㔚ሶ࡟࡯ࠩ(FEL)ࠍ↪޿ߡࡑࠢࡠࠬࠤ
࡯࡞ߩ 3 ᰴర C60 ࡐ࡝ࡑ࡯ (ࠬ࡯ࡄ࡯࠳ࠗࡗࡕࡦ࠼) ࠍวᚑߔࠆߣߎࠈߦ޽ࠆ‫ޕ‬
C60 ߇ࡐ࡝ࡑ࡯ࠍᒻᚑߔࠆߣ⿥⎬⾰᧚ᢱߣߥࠆน⢻ᕈ߇޽ࠆߚ߼‫ޔ‬㜞᷷㜞࿶ࡊࡠ࠮ࠬ⎇ⓥ߇ߥߐࠇߡ޿ࠆ‫ࡑޔߒ߆ߒޕ‬ࠢࡠࠬࠤ࡯࡞ߢߩන⋧ 3 ᰴరࡐ࡝ࡑ࡯ൻߪᧂߛ⏕⹺ߐࠇߡ޿ߥ޿‫⎇ᧄޔߢߎߘޕ‬ⓥߢߪࡎ࡯࡞࠼࡯ࡇࡦࠣߦࠃࠆലᨐߦ
ᵈ⋡ߒߚ‫ޔߢߣߎࠆߔࡊ࡯࠼ࠍ࡞࡯ࡎޕ‬C60 ߩ὇⚛ේሶߩࠛࡀ

C60 ಽሶ

࡞ࠡ࡯⁁ᘒߪ‫⿥ޔ‬㜞࿶ਅ (ᢙ GPa) ߦ߅ߌࠆ⁁ᴫߣห৻ⷞߔࠆ
ߎߣ߇ߢ߈ࠆ[1]‫࠲ࡊ࠮ࠢࠕޕ‬ర⚛ߣ C60 ᷙว‛ߦ࡟࡯ࠩᾖ኿
ߔࠆߎߣߢ‫ޔ‬㔚ሶബ⿠࡮⒖േߐߖ‫࡯ࡑ࡝ࡐޔ‬ൻ෻ᔕߩଦㅴࠍ

FEL⸘ߞߚ‫ޕ‬శḮߦߪ‫ޔ‬นᄌᵄ㐳․ᕈߣᄢ಴ജࠍ᦭ߔࠆ FEL ࠍណ↪ߒߚ‫ޕ‬

sp2 ⊛⚿ว

sp3 ⊛⚿ว‫⎇ޣ‬ⓥ᭎ⷐ‫ޤ‬ࠬ࡯ࡄ࡯࠳ࠗࡗࡕࡦ࠼
࿑ 1 ߦࠬ࡯ࡄ࡯࠳ࠗࡗࡕࡦ࠼ߩวᚑේℂࠍ␜ߔ‫ޕ‬1 ߟߩ὇⚛ේሶߪੑ㊀⚿วࠍ฽߻ sp2 ⊛ߥ⚿วߢሽ࿷ߒߡ޿ࠆ‫ߩߘޕ‬ੑ㊀⚿วࠍశࠛࡀ࡞ࠡ࡯ߢᛂߜಾࠅ‫ޔ‬૛ߞߚ㔚ሶࠍ㓞ធߔࠆ
C60 ಽሶߣߩ౒᦭⚿วߦ૶߁‫ࠍࠇߎޕ‬ㅪ⛯߆ߟ 3 ᰴర⊛ߦㅴ߼ࠆߎߣߢࠬ࡯ࡄ࡯࠳ࠗࡗࡕࡦ࠼ߪวᚑߐࠇࠆ‫ ߪࠇߘޕ‬C60
ߩᕈ⾰਄‫⿥࡮⾰⎬⿥ޔ‬シ㊂࡮⿥ᨵエߣ޿߁ 3 ߟߩ㛳⇣⊛․ᓽࠍ␜ߔ߽ߩߣ⠨߃ߡ޿ࠆ‫ޕ‬ర‫ ޿⎬ޘ‬C60 ߇࠳ࠗࡗࡕࡦ࠼ߦઍ
⴫ߐࠇࠆ sp3 ⊛⚿วߢ⒮ኒ᭴ㅧࠍߣࠆߣ‫ߩ⚖࠼ࡦࡕࡗࠗ࠳ޔ‬䉴䊷䊌䊷䉻䉟䊟䊝䊮䊄࿑ 1. 䉴䊷䊌䊷䉻䉟䊟䊝䊮䊄วᚑ
ේℂ䈫ಽሶ㓸ว䉟䊜䊷䉳࿑⎬ᐲߦട߃ߡ‫ޔ‬ౝㇱⓨᵢߦࠃࠅૐኒᐲ߆ߟシ㊂ߣߥࠆ‫ޔߚ߹ޕ‬C60 ಽሶ߇ធὐߢߩߺ⚿วߒߚ㕖᥏⾰᭴ㅧߪ‫ޔ‬ᒢᕈ࡮☼ᕈߦን߻ߣ⠨߃ࠆ‫ߩࠄࠇߎޕ‬ᕈ⾰߆ࠄ‫ߪ࠼ࡦࡕࡗࠗ࠳࡯ࡄ࡯ࠬޔ‬࿶ജࡑࠗࠢࡠ࡮࠽ࡁ࠺ࡃࠗࠬ‫⥶ޔ‬ⓨቝቮ߿ᑪ▽‫⥄ޔ‬േゞߩᣂߒ޿శቇ䊚䊤䊷᭴ㅧ᧚ᢱ‫ޔ‬ක≮ࠗࡦࡊ࡜ࡦ࠻ߥߤ‫ޔ‬᭽‫ߥޘ‬ಽ㊁ߢᵴべߢ߈ࠆᣂ⚛᧚ߣߥࠆ߽ߩߣᦼᓙߐࠇࠆ‫ޕ‬㩷 㩷 ⌀ⓨ䌆䌅䌌⹜ᢱశቇ䉡䉞䊮䊄䉡

ታ㛎⹜ᢱߪ⌀ⓨਛߢട࿶࡮⚡ᄖ✢ᾖ኿ߔࠆߎߣߦࠃࠅ૞⵾ߒߚ‫ޕ‬
C60 ☳ᧃߩߺߩࠨࡦࡊ࡞ߣ‫ ߡߒߣ࠲ࡊ࠮ࠢࠕޔ‬I2 ࠍ㊀㊂Ყ
1:1 ߢᷙ౉ߒߚ 2 ࡄ࠲࡯ࡦࠍ૶↪ߒ‫ޔ‬I2 ߩ᦭ήߦࠃࠆ㆑޿

࿑ 2. ታ㛎ⵝ⟎࿑ߢࡎ࡯࡞࠼࡯ࡊߩലᨐࠍ⹏ଔߒߚ‫ࠩ࡯࡟ޕ‬ᵄ㐳ߪၮᧄᵄ 1450nm ߣ 3 ୚㜞⺞ᵄߩ 450nm ࠍᾖ኿ߒߚ‫ࡦ࠯ࡦࡌߪࠇߎޕ‬Ⅳߩ⚿วࠛࡀ࡞ࠡ࡯ࠃࠅ⷗Ⓧߞߚ‫ޔ‬C60 ߩੑ㊀⚿วࠍᛂߜಾࠆߩߦᔅⷐߥࠛ
ࡀ࡞ࠡ࡯ࠍ߽ߞߚᵄ㐳ߢ޽ࠆ‫ࠩ࡯࡟ޕ‬ᒝᐲߪ ᢙ 10PJ/Pulse‫ࠅ➅ޔ‬㄰ߒᾖ኿๟ᵄᢙ 2Hz ߢ 300minᾖ኿ߒߚ‫⹏ޕ‬ଔⵝ⟎ߦߪ࡜ࡑࡦಽశ‫ޔ‬XRD ࠍ૶↪ߒߚ‫ޕ‬⚿ᨐ࡮⠨ኤ
࿑ 3 ߦ XRD ࡄ࠲࡯ࡦࠍ␜ߔ‫ޕ‬FEL ᾖ኿ߦࠃࠅฦ‫ߩޘ‬(311)㕙ߦ߅޿ߡ࿁᛬ⷺߩჇട‫ޔ‬I2 ᷙวࠨࡦࡊ࡞ߢߪ (111)‫ޔ‬

(200)

(111)

㩷

࿁᛬ⷺߩჇടߪ㕙㑆㓒ߩ❗ዊࠍᗧ๧ߒ‫ࠢ࡯ࡇޔ‬ᒝᐲߩᄌ

FEL ᾖ኿ᓟ C60

ࠇࠆ‫ޕ‬

FEL ήᾖ኿ C60 & I2㩷⥰߁৻ᣇ‫৻ޔ‬ㇱߢ C60 ߣጀ㑆ൻว‛ࠍᒻᚑߒߚߣ⠨߃ࠄ࿁᛬ᒝᐲ [ a.u. ]৻⥌ߒߥ޿‫ޔࠄ߆ߣߎߩߎޕ‬I2 ߪࡎ࡯࡞࠼࠽࡯ߣߒߡᝄ

㩷( 111 )

C60(I2)x ࠍᒻᚑߒߡ޿ࠆ႐ว‫ ᧪ᧄޔ‬C60 ߩ߽ߞߡ޿ࠆ
(111) 㕙ߩࡇ࡯ࠢߪᶖᄬߔࠆߪߕߢ޽ࠅ‫⚿ޔ‬ᨐࠣ࡜ࡈߣߪ

㩷

(222)
FEL ήᾖ኿ C60

ൻߪ⚿᥏ᕈߩૐਅࠍ␜ߔ‫߇࡞ࡊࡦࠨޕ‬ቢోߦጀ㑆ൻว‛( 311 )

(࿑ਛ⍫ශ) ߽⃻ࠇߚ‫ޕ‬( 200 )

ᐲᲧߩᄌൻࠍ⏕⹺ߒߚ‫ޔߚ߹ޕ‬C60(I2)x ߣ⷗ࠄࠇࠆࡇ࡯ࠢ

࿁᛬ᒝᐲ [ a.u. ](222) 㕙ࠍߪߓ߼‫ޔ‬ฦࡇ࡯ࠢᒝᐲߩ⪺ߒ޿ᷫዋߣࡇ࡯ࠢᒝ

࿑ 4 ߦ࡜ࡑࡦಽశߩ᷹ቯ⚿ᨐࠍ␜ߔ‫ޕ‬FEL ᾖ኿ߦࠃࠅ

FEL ᾖ኿ᓟ C60 & I2

Ag(2) ᝄേࡕ࡯࠼ߩᵄᢙ߇ 3.2cm-1 ࡑࠗ࠽ࠬ஥ߦࠪࡈ࠻
5ߒ‫ޔ‬I2 ᷙ౉ࠨࡦࡊ࡞ߦ߅޿ߡߪ 7.5cm-1 ߩᄢ߈ߥࠪࡈ࠻

10

15

20

25

2ǰ [ deg ]ࠍ⏕⹺ߒߚ‫ޕ‬࿑ 3. XRD 䊌䉺䊷䊮Ag(2) ࡕ࡯࠼ߣߪ‫ޔߦ߁ࠃߔ␜ߦࡈ࡜ࠣޔ‬ฦ὇⚛ේሶ߇
੖ຬⅣߩਛᔃߦ㓸߹ࠆࠃ߁ߦᝄേߔࠆࡕ࡯࠼ߢ޽ࠆ‫ޕ‬C60

Ag(2)1455.4 1459.7

߇ࡐ࡝ࡑ࡯ൻߔࠆߣಽሶ㑆ߦ⊒↢ߔࠆ⚿วߦࠃߞߡ C60
േ߇೙㒢ߐࠇ‫⚿ޔ‬ᨐߣߒߡᝄേᢙߩᄌൻߦߟߥ߇ࠆ‫ޕ‬ੑ㊂-1

૕ (࠳ࠗࡑ࡯) ࠍᒻᚑߔࠆߣߎߩ Ag(2) ࡕ࡯࠼߇ 10cmࡑࠗ࠽ࠬ஥߳ࠪࡈ࠻ߔࠆߣߩႎ๔[ 2 ]߇޽ࠆ߇‫ޔ‬C60 ߇ 3છᗧᒝᐲ [ a.u. ]ࠍ᭴ᚑߔࠆ὇⚛ේሶ㑆ߩ〒㔌߇⧯ᐓᄌൻߒ‫޿઻ߦࠇߘޔ‬ᝄ

1462.9FEL ᾖ኿ᓟ C60 & I

FEL ᾖ኿ᓟ C60
FEL ήᾖ኿ C60

ᰴర⊛ߦࡐ࡝ࡑ࡯ൻߒߚ႐วߤߩ⒟ᐲࠪࡈ࠻ߔࠆߩ߆᣿
⏕ߥ୯ߪ᣿ࠄ߆ߦߥߞߡ޿ߥ޿‫࡯ࡑࠗ࠳ޔߛߚޕ‬ൻࠃࠅⶄ㔀ߦ⚿วߔࠆ 3 ᰴరࡐ࡝ࡑ࡯ൻߪ‫ߩߘޔ‬ᝄേ೙㒢߽ỗߒ

1420

1430

1440

1450

1460

1470

1480

1490

ᵄᢙ [ cm-1 ]࿑ 4. 䊤䊙䊮ಽశߊ‫߽࠻ࡈࠪޔ‬ᄢ߈޿ߣ੍ᗐߐࠇࠆ‫ޔࠄ߆ߣߎߩߎޕ‬I2 ࠍᷙ౉ߒࡎ࡯࡞࠼࡯ࡊߒߚߎߣߢ‫ࠅࠃޔ‬ᄢ߈ߥࠪࡈ࠻ࠍ⏕⹺ߒߚߎߣߪ‫࡯ࡑ࡝ࡐ߇ࠣࡦࡇ࡯࠼࡞࡯ࡎޔ‬ൻߦ᦭ലߢ޽ࠆߎߣࠍ␜ໂߒߡ޿ࠆ[3]‫ޕ‬䇼䉁䈫䉄䇽
XRD ࠃࠅ‫⚿ޔ‬᥏ᕈߩૐਅ‫৻ޔ‬ㇱߢጀ㑆ൻว‛ C60(I2)x ߩᒻᚑࠍ⏕⹺ߒߚ‫ࡦࡑ࡜ޕ‬ಽశߦࠃࠅ‫ޔ‬Ag(2) ࡕ࡯࠼߇ 7.5cm-1 ࠪࡈ࠻ߔࠆߎߣࠍ⏕⹺ߒ‫࡯ࡑ࡝ࡐ߇ࡊ࡯࠼࡞࡯ࡎޔ‬ൻࠍଦㅴߒߚߎߣࠍ⏕⹺ߒߚ‫੹ޕ‬࿁‫ޔ‬ᚲᦸߔࠆࠬ࡯ࡄ࡯࠳ࠗࡗࡕࡦ࠼ࠍᓧࠆߦߪ⥋ࠄߥ߆ߞߚ߇‫ޔ‬శബ⿠ࡎ࡯࡞࠼࡯ࡊߣ

޿߁ࠕࡊࡠ࡯࠴ߢ C60 ߩ‛ᕈ߇ᄌൻߔࠆߎߣࠍ⏕⹺ߒߚ‫߇࠼ࡦࡕࡗࠗ࠳࡯ࡄ࡯ࠬߪࠇߎޕ‬วᚑน⢻ߢ޽ࠆߎߣࠍ␜ໂߒߡ߅ࠅ‫੹ޔ‬ᓟᒻᚑ᧦ઙߩᦨㆡൻࠍߪ߆ࠆߎߣߦࠃߞߡ‫ޔ‬ᄞߩᣂ⚛᧚ࠍഃ⵾ߔࠆ
ߎߣ߇಴᧪ࠆ߽ߩߣᦼᓙߐࠇࠆ‫ޕ‬ෳ⠨ᢥ₂[ 1 ] Hiroyuki Nakayama and Hiroshi Katayama, Jan.J.Appl.Phys, 41(2002)817.
[ 2 ] G. B. Adams et al., Phys. Rev. B, 50(1994)15.
[ 3 ] ᯅᧄ, ⍹Ꮉ, ጤ↰, ጊᧄ, ╙ 52 ࿁ᔕ↪‛ℂቇ㑐ଥㅪว⻠Ṷળ, 31p-ZC-9(2005).

䇼⎇ⓥᬺ❣╬䇽࡮⊒⴫⺰ᢥ(1) Y. Shimizu, K. Saito, T. Sakuma, N. Iwata and H. Yamamoto: “Electronic Transportation Anomaly
Observed in Interfaces of Nanostructured C60 Monolayers and Ultrathin Au Films”, Proceeding of
IUMRS-ICA 2004(Tsintsu, Taiwan, 17-18th Nov. 2004),(2005)pp.1-6.
(2) N. Iwata, K. Fukai and H. Yamamoto: “Crystallization and Conductivity of ReO3 Thin Films Prepared by
90º Off-Axis RF Magnetron Sputtering Method”, IEICE Trans. Electron, E87-C (2004) pp.223-226(3) Y. Shimizu, K. Saito, T. Sakuma, N. Iwata and H. Yamamoto: “Electronic Transport Properties of C60
Derivative Self-Assembly Monolayer on Au Ultrathin Film”, Trans. of the Mate. Res. Soc. Jpn., 29(2004) 1323-1326.
(4) T. Kato, S. Yamaguchi, A. Takahashi, N. Iwata and H. Yamamoto: “Chromogenic Responses Induced byElectric Field in Phthalocyanine Derivative LB Films”, Trans. of the Mate. Res. Soc. Jpn., 29 (2004)
759-762.
(5) A. Noguchi, J. Kurian, T. Amemura, K. Tanabe, T. Morishita, N. Iwata, H. Yamamoto, M.Kusunoki, M.
Mukaida and S. Ohshima: “Preparation and Characterization of NdBa2Cu3O7-G thin films on MgOsubstrates with Ba2NdTaO6 buffer layers”, Trans. of the Mate. Res. Soc. Jpn., 29 (2004) 1269-1272.
(6) K. Fukai, M. Masui, N. Iwata and H. Yamamoto: “Conductive Properties of ReO3 / SrCuO2 Bilayered
Films”, Trans. of the Mate. Res. Soc. Jpn., 29 (2004) 1315-1318.
(7) Y. Nakajima, H. Kokubun, T. Amemura, N. Iwata, Y. Tarutani, K. Tanabe, T. Morishita and H. Yamamoto:“Preparation of Josephson Junctions by MOCVD films”, Trans. of the Mate. Res. Soc. Jpn., 29 (2004)
1331-1334.
(8) N. Iwata, K. Matsuo and H. Yamamoto: “Preparations and Evaluations of Magnetoelectric Oxides /Superconductor Multilayers”, Trans. of the Mate. Res. Soc. Jpn., 29 (2004) 1437-1440.
(9) H. Yamamoto, N. Iwata, and Y. Shimizu: “Nano-Structured C60-SAM Formed on Ultrahthin Au
Films/MgO Single Crystal”, Technical Proceedings of NSTI Nanotech 3 (2004) pp. 441-444.
(10) N. Iwata, K. Matsuo, N. Ootsuka and H. Yamamoto: “Preparations and Evaluations of MagnetoelectricThin Films for Josephson Field Effect Transistor”, Mat. Res. Soc. Symp. Proc., 811 (2004) pp.425-430.
(11) ਛ᎑, ࿖ಽ, 㘸᧛, ጤ↰, ᮻ⼱, ↰ㄝ, ᫪ਅ, ጊᧄ, ోᎿ⒟ MOCVD ᴺߦࠃࠆ࡚ࠫ࠮ࡈ࠰ࡦធว
ߩ૞⵾, 㔚ሶᖱႎㅢାቇળᛛⴚႎ๔, SCE2003-2(April 2003) pp.9-13.
(12) ᅏጊ, ㊄ၔ, ጤ↰, ጊᧄ, C60 ૐᰴర࠽ࡁ᭴ㅧ⿥⭯⤑ߩᒻᚑ, 㔚ሶᖱႎㅢାቇળᛛⴚႎ๔, Vol.103,
No.245(2003)pp.1-6.
(13) ᅏጊ, ㊄ၔ, 㐳ጊ, ጤ↰, ጊᧄ, ౣ⫳⊒ᴺߦࠃࠆ C60 ⿥⭯⤑࠽ࡁ᭴ㅧ, 㔚ሶᖱႎㅢାቇળᛛⴚ⎇ⓥႎ๔, Vol. 103, No.411(2003)pp.27-32.
(14) ᷓ੗, ᪊੗, ጤ↰, ጊᧄ, ࠬࡄ࠶࠲ᴺߦࠃࠆ ReO3/SrCuO2 Ⓧጀ⤑ߩ૞⵾, 㔚ሶᖱႎㅢାቇળᛛ
ⴚ⎇ⓥႎ๔, Vol. 103, No.411(2003)pp.33-38.
(15) H. Yamamoto, K. Fukai, K. Matsuo, N. Iwata, Optical and conductive properties of ReO3 sputtered thinfilms, Proc. of The 7th International Symposium on Sputtering & Plasma Processes-ISSP2003-(2003)
pp.206-209.
(16) Nobuyuki Iwata, Keigo Mukaimoto, Hiroyuki Imai and Hiroshi Yamamoto, Transport properties of C60
ultra-thin films, Surf. Coat. Tech. 169-170 (2003)pp. 646-649.

(17) N. Iwata and H. Yamamoto, SYNTHESIS OF SINGLE-CRYSTALLINE C60 ULTRATHIN FILMS BY
VACUUM EVAPORATION, Proceeding of “1st International Conference on Materials Processing for
Properties and Performance[MP3]”, Eds by K. H. Khor, S. Y. Zhang, P. Hing, and F. Boey, Institute ofMaterials [East Asia], (2003) pp.772-779.
(18) N. Iwata and H. Yamamoto, Synthesis of C60 Monolayer with One-Dimensional Nano-Structure, Proc. of
The 5th Joint Seminar of China-Japanese Amity Universities, pp.54-59(2003).
(19) K. Onozuka, N. Iwata, and H. Yamamoto: Novel vacuum system for in-situ characterization offluorescence properties of thin films, Int. J. Mod. Phys. B, 16, 28&29(2002)pp.4445-4448.
(20) K. Suzuki, M. Okamoto, S. Alsadoon, N. Iwata, H. Yamamoto: Chromogenic properties of
Phthalocyanine Derivatives Langmuir-Blodgett Films, Trans. Mate. Res. Soc. Jpn., Vol. 27, No.
2(2002)pp345-348.
(21) M. Ohkubo, K. Fukai, N. Iwata and H. Yamamoto: Preparations of conductive ReO3 thin films,
Superconductor Science and Technology (SuST), Vol. 15, No. 12(2002)pp.1778-1780.
(22) H. Imai, N. Iwata and H. Yamamoto: Synthesis of C60 self-assembled monolayer on Au ultrathin films,
Nanotechnology, Vol. 13(2002)pp.768-770.
(23) M. Ohkubo, K. Fukai, N. Iwata, and H. Yamamoto: Preparation of Conductive Re Oxide Thin Films by
Sputtering, Technical Report of IEICE, Vol.102, No.434(2002)pp.23-28. (in Japanese)(24) N. Iwata, H. Okuyama, S. Kuroda, Y. Shimizu, H. Imai, and H. Yamamoto: Low Dimensional
Nano-Structure of C60 Thin Films, Technical Report of IEICE, Vol.102, No.260(2002)pp.13-17. (inJapanese)(25) H. Yamamoto, H. Isogai, and Y. Yoshida: Low-voltage electron beam excitement luminescence of oxidethin films with multilayered structure, Thin Solid Films,383(2001)pp.89-91.
(26) N. Iwata, N. Hashimoto, and H. Yamamoto: Preparation of Continuous C60 Thin Films with Flat
Surfaces by Vacuum Evaporation, Trans. of the MRS-J, Vol. 26, No. 4(2001)pp.1339-1342.
(27) K. Suzuki, T. Kato, Y. Nakamura, N. Iwata, and H. Yamamoto: Preparation of Phthalocyanine
Derivative Ultrathin Films by Langmuir-Blodgett Method, Trans. of the MRS-J, Vol. 26, No.
4(2001)pp.1335-1338.
(28) ጤ↰ዷᐘ‫ޔ‬ะᧄ࿻๋‫ޔ‬ᷡ᳓೑ᨑ‫੹ޔ‬੗ඳⴕ‫ޔ‬ጊᧄኡ: ‫ޟ‬C60 ⭯⤑ߩ㔚⇇ലᨐࠍ߼ߑߒߡ‫ޠ‬, 㔚ሶᖱႎㅢାቇળᛛⴚ⎇ⓥႎ๔, CPM2001-103, Vol.101 (2001-10)pp.67-72.
(29) ੹੗ඳⴕ‫ޔ‬ዊᨋኡ‫ޔ‬ᷡ᳓೑ᨑ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, ‫ޟ‬C60 ⺃ዉ૕⥄Ꮖ⚵❱නಽሶ⤑ߩ૞⵾ߣ⹏
ଔ‫ޠ‬, 㔚ሶᖱႎㅢାቇળᛛⴚ⎇ⓥႎ๔ᦠ, CPM2001-104, Vol. 101(2001-10)

pp.73-78.

(30) ᄢਭ଻ቇ‫᧻ޔ‬የᐘᴦ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, ‫ޟ‬Re ㉄ൻ‛⭯⤑ߩ⊒⦡ߣવዉᕈ‫ޠ‬, 㔚ሶᖱႎㅢାቇ
ળᛛⴚ⎇ⓥႎ๔, CPM2001-110, Vol.101(2001-10) pp.107-112.
(31) N. Iwata, Y. Ishii, H. Yamamoto, H. Zama, T. Morishita, and K. Kohn: Ferromagnetic Insulator EuOThin Film, Ferrites : Proceedings of ICF8, (2000)pp.642-644.
࡮ቇળ⊒⴫
8th International Superconductive Electronics Conference ISEC'01, Osaka Sun Palace, Osaka, Japan,
2001.06.19-06.22(1) Nobuyuki Iwata, Hiroyuki Imai, Hiroshi Yamamoto, Experimental Verification of Superconductivity

Expected in Interface of Dielectric and C60 Thin films, P1-G8International Conference on Materials for Advanced Technologies (ICMAT'01), Singapore
International Convention & Exhibition Centre, 2001.07.01-07.06(1) Nobuyuki Iwata, Manabu Ohkubo and Hiroshi Yamamoto, Preparations of ReOx thin films and SrCuO2 /ReOx multilayered films, P12-11
VII International Conference on Advanced Materials㧔ICAM 2001㧕, J.W.Marriott, Punta Cancun,
Cancun Quintana-Roo, Mexico, 2001.08.26-08.30(1) (Invited) Hiroshi Yamamoto, Nobuyuki Iwata, Hiroyuki Imai and Keigo Mukaimoto, Synthesis andproperties of very smooth C60 ultrathin films by vacuum evaporation, 13-7SA
Frontiers of Surface Engineering 2001 (FSE2001) Conference and Exhibition, Nagoya Congress Center,
Nagoya, Japan, 2001.10.28-11.01(1) Nobuyuki Iwata, Keigo Mukaimoto, Hiroyuki Imai and Hiroshi Yamamoto, Transport Properties of C60
ultrathin films, D4-14
First East Asia Symposium on Superconductive Electronics EASSE 2001, New Industry Creation
Hatchery Center (NICHe), Tohoku University, Sendai, 2001.11.26-11.28(1) Estimation of Cooling Performance of Pulse Tube Cryocooler, PS-23
XUT-NU JOINT SYMPOSIUM ON ELECTRICAL ENGINEERING AND ELECTRONIC ANDCOMPUTER SCIENCE, Xi'an University of Technology, 2001.9.21(1) Hiroahi Yamamoto and Nobuyuki Iwata, NANO-SYNTHESIS PROCESS AIMING AT MOLECULAR
ELECTRONICS╙ 8 ࿁㔚᳇ቇળ ᦭ᯏ⭯⤑࡮ಽሶ⿥⭯⤑෸߮᦭ᯏ࡮ήᯏⶄว⤑ߩᯏ⢻ൻ⺞ᩏኾ㐷ᆔຬળ, ᧲੩Ꮏᬺᄢቇ, 2001.10.28(1) ጊᧄኡ‫ޔ‬ጤ↰ዷᐘ, NANO-SYNTHESIS PROCESS AIMING AT MOLECULAR ELECTRONICS
㔚ሶᖱႎㅢାቇળ 㔚ሶㇱຠ᧚ᢱ⎇ⓥળ-⭯⤑ࡊࡠ࠮ࠬ࡮᧚ᢱ, ାᎺᄢቇᎿቇㇱ, 2001.10.26(1) ੹੗ඳⴕ‫ޔ‬ዊᨋኡ‫ޔ‬ᷡ᳓೑ᨑ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, C60 ⺃ዉ૕⥄Ꮖ⚵❱නಽሶ⤑ߩ૞⵾ߣ⹏ଔ,CPM2001-104(2) ᄢਭ଻ቇ‫᧻ޔ‬የᐘᴦ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, Re ㉄ൻ‛⭯⤑ߩ⊒⦡ߣવዉᕈ, CPM2001-110(3) ጤ↰ዷᐘ‫ޔ‬ะᧄ࿻๋‫ޔ‬ᷡ᳓೑ᨑ‫੹ޔ‬੗ඳⴕ‫ޔ‬ጊᧄኡ, C60 ⭯⤑ߩ㔚⇇ലᨐࠍ߼ߑߒߡ, CPM2001-103
ቇળฬ㧦㔚ሶᖱႎㅢାቇળ⎇ⓥળ 㧔㔚ሶㇱຠ࡮᧚ᢱ㧕̅⭯⤑ࡊࡠ࠮ࠬ࡮᧚ᢱ‫̅⥸৻ޔ‬╙ 45 ࿁ℂᎿቇㇱቇⴚ⻠Ṷળ㧔᧚ᢱ࡮‛ᕈㇱળ, ᣣᧄᄢቇℂᎿቇㇱ⦁ᯅᩞ⥢㧔13 ภ㙚㧕, 2001.11.13(1) ዊᨋኡ‫੹ޔ‬੗ඳⴕ‫ޔ‬ᷡ᳓೑ᨑ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, C60 ⺃ዉ૕ߦࠃࠆ⥄Ꮖ⚵❱නಽሶ⤑ߩ૞⵾, Ca6(2) ਛ᎑㓶৻‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ‫ޔ‬㜞ᯅ⟵ᐢ‫ޔ‬᫪ਅᔘ㓉, MOCVD ᴺߦࠃࠆ Sr2AlTaO6 ⛘✼⭯⤑ߩၮ
᧼᷷ᐲ․ᕈ, Ca4(3) ᧻የᐘᴦ‫ޔ‬ᄢਭ଻ቇ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, ෻ᔕᕈ RF ࠬࡄ࠶࠲ߦࠃࠆ Re ㉄ൻ‛⭯⤑ߩ૞⵾ߣ⹏
ଔ, Ca3(4) ጟᧄ ᱜผ‫ޔ‬㋈ᧁ ⥶਽‫ޔ‬Alsadoon Saliman‫ޔ‬ጤ↰ ዷᐘ‫ޔ‬ጊᧄ ኡ, ࡈ࠲ࡠࠪࠕ࠾ࡦ⺃ዉ૕ LB ⭯⤑ߩ᭴ㅧ⹏ଔߣࠢࡠࡒ࠭ࡓ, Ca7(5) ᧘ ᐲද‫ޔ‬ዊ㊁Ⴆ ᶈᐔ‫ޔ‬ጤ↰ ዷᐘ‫ޔ‬ጊᧄ ኡ, ᦭ᯏ EL ↪Ⱟశ⭯⤑ߩ૞⵾ߣ⹏ଔ, Ca8(6) ᰞᴛ ⌀ੱ‫ޔ‬ጤ↰ ዷᐘ‫ޔ‬ጊᧄ ኡ‫ޔ‬ᚬ Ꮀ‫᧻ޔ‬ේ ᵗ৻, ࡄ࡞ࠬ▤಄ಓᯏߩ಄ಓ․ᕈ੍᷹, Cp9(7) ะᧄ࿻๋‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, C60 ⭯⤑ߩ૞⵾ߣ⚿᥏⹏ଔ, Ca5

(8) ㊁ญ┨‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ‫ޔ‬᫪ਅᔘ㓉, ࠝࡈࠕࠢࠪࠬ DC-RF ࡂࠗࡉ࡝࠶࠼ࡑࠣࡀ࠻ࡠࡦࡊ࡜࠭
ࡑࠬࡄ࠶࠲࡝ࡦࠣᴺߦࠃࠆ NdBa2Cu3O7-d ⭯⤑ߩ૞⵾ߣ⹏ଔ, Ca2
㔚᳇ൻቇળ╙ 68 ࿁ᄢળ, ␹ᚭᄢቇᎿቇㇱ, 2001.4.1-3(1) ᄢਭ଻ቇ㧘ᱞ੗ㄖᙗ㧘ጤ↰ዷᐘ㧘ጊᧄኡ, Re ㉄ൻ‛⤑ߩశๆ෼ࠬࡍࠢ࠻࡞, 1I32
(2) ㋈ᧁ ⥶਽‫ޔ‬ട⮮ᢘᐘ‫ޔ‬ਛ᧛ 㓶৻‫ޔ‬ጤ↰ ዷᐘ‫ޔ‬ጊᧄ ኡ, ࡈ࠲ࡠࠪࠕ࠾ࡦ⺃ዉ૕ LB ⿥⭯⤑૞⵾ߣࠢࡠࡒ࠭ࡓ, 1㧵31
ᐔᚑ 13 ᐕᐲᣣᧄ౮⌀ቇળ, ජ⪲ᄢቇߌ߿߈ળ㙚, 2001.5.22-23(1) ㋈ᧁ ⥶਽‫ޔ‬ട⮮ᢘᐘ‫ޔ‬ጤ↰ ዷᐘ‫ޔ‬ጊᧄ ኡ, LB ᴺߦࠃࠆࡈ࠲ࡠࠪࠕ࠾ࡦ⺃ዉ૕⤑ߩ૞⵾, C05╙ 13 ࿁ ᣣᧄ MRS ቇⴚࠪࡦࡐࠫ࠙ࡓ‫␹ޔ‬ᄹᎹ⋵ࠨࠗࠛࡦࠬࡄ࡯ࠢ, 2001.12.21(1) ᷡ᳓೑ᨑ‫ޔ‬ዊᨋኡ‫੹ޔ‬੗ඳⴕ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, Preparations and Evaluations of Self - Assembly
Monolayers of C60 Derivatives, B2-P10-M(2) ㋈ᧁ ⥶਽‫ޔ‬ጟᧄ ᱜผ‫ޔ‬Alsadoon Saliman‫ޔ‬ጤ↰ ዷᐘ‫ޔ‬ጊᧄ ኡ, ࡈ࠲ࡠࠪࠕ࠾ࡦ⺃ዉ૕ LB ⤑ߩࠢࡠࡕࠫࠚ࠾࠶ࠢ․ᕈ, G01-O03╙ 49 ࿁ᔕ↪‛ℂቇ㑐ଥㅪว⻠Ṷળ, ᧲ᶏᄢቇ‫ޔ‬ḕධᩞ⥢, 2002.3.27-30(1) ੹੗ඳⴕ‫ޔ‬ዊᨋኡ‫ޔ‬ᷡ᳓೑ᨑ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, C60 ⺃ዉ૕⥄Ꮖ⚵❱නಽሶ⤑ߩ૞⵾ߣ㔚᳇વ
ዉ․ᕈ, 29p-YN-12(2) ᶏ⠧ᴛᙗ৻‫ޔ‬㒸ஜ‫ޔ‬ਛፉஜ੺‫ޔ‬ጊਅദ‫ޔ‬ᰞᴛ⌀ੱ‫ޔ‬ጊᧄኡ‫᧻ޔ‬ේᵗ৻, ዊဳࡄ࡞ࠬ▤಄ಓᯏߦ៞タߒߚ㜞᷷⿥વዉ࡚ࠫ࠮ࡈ࠰ࡦធวߩࡁࠗ࠭․ᕈ, 29a-ZS-10╙ 66 ࿁ 2002 ᐕᐲᤐቄ ૐ᷷Ꮏቇ࡮⿥વዉቇળ, Ꮏቇ㒮ᄢቇ ᣂኋᩞ⥢, 2002.5.18-20(1) ᰞᴛ⌀ੱ ጤ↰ዷᐘ ጊᧄኡ ᚬᎰ ᧻ේᵗ৻, 㧶㧶⚛ሶ಄ළߩߚ߼ߩࡄ࡞ࠬ▤಄ಓᯏ, D3-2
The 8th International Union of Materials Research Societies (IUMRS) - International Conference on
Electronic Materials (ICEM), ⷏቟‫ᦛޔ‬ᳯ⾠㙚, 2002.6.10-14(1) Hiroyuki Imai, Nobuyuki Iwata and Hiroshi Yamamoto, Synthesis of C60-SAM on Au ultrathin films,
E40(2) Manabu Ohkubo, Kumiko Fukai, Nobuyuki Iwata and Hiroshi Yamamoto, Preparations of conductive
ReO3 thin films, L86(3) Nobuyuki Iwata, Shinji Kuroda, Hiroki Okuyama and Hiroshi Yamamoto, Transport properties of C60
thin films, E41(4) Takayuki Kato, Saliman Alsadoon, Nobuyuki Iwata and Hiroshi Yamamoto, Electrochromic properties of
Phthalocyanine derivative Langmuir -Blodgett films, E39(5) Kohei Onozuka, Nobuyuki Iwata, and Hiroshi Yamamoto, Novel vacuum system for in-situ
characterization of fluorescence properties of thin films, H63╙ 23 ࿁ࡈ࡜࡯࡟ࡦ࡮࠽ࡁ࠴ࡘ࡯ࡉ✚วࠪࡦࡐࠫ࠙ࡓ, ᧻ፉ‫᧻࡞࠹ࡎޔ‬ፉᄢⷰ⨿, 2002.7.17-19(1) Nobuyuki Iwata, Hiroki Okuyama, Shinji Kuroda, Hiroyuki Imai, Yoshiki Shimizu, and Hiroshi
Yamamoto, Low Dimensional Nano-Structure for C60, 1P-51
㔚ሶᖱႎㅢାቇળ㔚ሶㇱຠ࡮᧚ᢱ⎇ⓥળ, ⋓ጟ‫ޔ‬ጤᚻᄢቇ, 2002.8.8(1) ጤ↰ዷᐘ‫ޔ‬ᅏጊඳၮ‫ޔ‬㤥↰⌀ม‫ޔ‬ᷡ᳓⧐⾆‫੹ޔ‬੗ඳⴕ‫ޔ‬ጊᧄኡ, C60 ⭯⤑ߩૐᰴర࠽ࡁ᭴ㅧ,CPM2002-53
The 2nd International Meeting on Information Display, 㖧࿖‫ޔ‬ᄢ㇗ EXCO, 2002.8.21-23(1) (Invited)Takayuki Kato, Saliman Alsadoon, Nobuyuki Iwata and Hiroshi Yamamoto, Novel Chromogenic

Materials Expected for Future FPD, 16.2
1st International Conference on Materials Processing for Properties and Performance (MP3), ࠪࡦࠟࡐ࡯࡞‫࡞࡯ࡐࠟࡦࠪ࡮࡞ࠕ࠾࠹ࡦ࠮࡮࠼࠶࡜ࡦࠦޔ‬, 2002.8.1-3(1) Nobuyuki Iwata and Hiroshi Yamamoto, SYNTHESIS OF SINGLE-CRYSTALLINE C60 ULTRATHINFILMS BY VACUUM EVAPORATION, Thin Films & Coatings Session #2-3
The 4th Joint Seminar of NU-XUT, ᣣᧄᄢቇℂᎿቇㇱ‫⦁ޔ‬ᯅᩞ⥢, 2002.9.9(1) Nobuyuki IWATA and Hiroshi YAMAMOTO, Materials Science of C60 Ultrathin Films╙ 63 ࿁ᔕ↪‛ℂቇળቇⴚ⻠Ṷળ, ᣂẟ‫ޔ‬ᣂẟᄢቇ, 2002.9.24-27(1) ㊁ญ┨‫ޔ‬J.Kurian‫ޔ‬㘸᧛㓉‫ޔ‬ጤ↰ዷᐘ‫↰ޔ‬ㄝ࿻৻‫ޔ‬᫪ਅᔘ㓉‫ޔ‬ጊᧄኡ, Tc㧪91K,NdBa2Cu3O7-Ǭ
⭯⤑ߩߚ߼ߩ Ba2NdTaO6 ࡃ࠶ࡈࠔઃ߈ MgO ၮ᧼, 26p-H-12/I(2) ਛ᎑㓶৻‫ޔ‬ጤ↰ዷᐘ‫↰ޔ‬ㄝ࿻৻‫ޔ‬᫪ਅᔘ㓉‫ޔ‬ጊᧄኡ, YBa2Cu3O7-x ෘ⤑਄ߦⓍጀߒߚ Sr2AlTaO6⭯⤑⴫㕙ߦ޽ࠄࠊࠇࠆ☸ሶߩ⊒↢ේ࿃, 26a-H-8/I╙ 67 ࿁ 2002 ᐕᐲ⑺ቄ ૐ᷷Ꮏቇ࡮⿥વዉቇળ, 㐳ፒࡉ࡝࠶ࠢࡎ࡯࡞, 2002.10.30-11.1(1) ᶏ⠧ᴛᙗ৻䇮㒸ஜ䇮ਛፉஜ੺䇮ጊਅദ䇮ᰞᴛ⌀ੱ䇮ጊᧄኡ䇮᧻ේᵗ৻, ዊဳ䊌䊦䉴▤಄ಓᯏ䈮៞タ䈚䈢㜞᷷⿥વዉ䉳䊢䉶䊐䉸䊮ធว䈱䊉䉟䉵․ᕈ, 3D-a08╙ 45 ࿁ℂᎿቇㇱቇⴚ⻠Ṷળ, ᣣᧄᄢቇℂᎿቇㇱ‫⦁ޔ‬ᯅᩞ⥢, 2002.11.20(1) ጊญჽ᮸‫ޔ‬ട⮮ᢘᐘ‫ޔ‬Alsadoon Saliman‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, ITO ၮ᧼⴫㕙⁁ᘒߩ㆑޿ߦࠃࠆ LB⭯⤑ߩ᭴ㅧ࡮శๆ෼․ᕈ
(2) ☨Ⴧᜏ㇢‫ޔ‬ዊ㊁Ⴆᶈᐔ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄ ኡ, ᦭ᯏ᧚ᢱߩⰯశ⊒శᯏ᭴ߩᬌ⸛
(3) ᅏጊඳၮ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, C60 ⿥⭯⤑ߩૐᰴర࠽ࡁ᭴ㅧ
(4) 㤥↰⌀ม‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, 㔚⇇ലᨐ࠻࡜ࡦࠫࠬ࠲࡯ࠍ⋡ᜰߒߚ C60 ⿥⭯⤑ߩ૞⵾ߣ㔚᳇વዉᕈ(5 )⷏᧛଻ᐢ‫੹ޔ‬੗ඳⴕ‫ޔ‬ᷡ᳓⧐⾆‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, C60 ⺃ዉ૕⥄Ꮖ⚵❱නಽሶ⤑ߩ૞⵾ߣߘߩ
㔚᳇વዉ․ᕈ
(6) ⍹Ꮉ⾆ਯ‫੹ޔ‬੗ඳⴕ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, C60 ࡐ࡝ࡑ࡯ൻ෻ᔕߦࠃࠆࠬ࡯ࡄ࡯࠳ࠗࡗࡕࡦ࠼วᚑ
(7) ᰞᴛ⌀ੱ ዊᨋ໪ᔒ ጊᧄኡ ᧻ේᵗ৻ ㇺਣ㓉ⴕ, ࠗࡦ࡜ࠗࡦဳࡄ࡞ࠬ▤಄ಓᯏߩᝄേ᷹ቯ
㔚ሶᖱႎㅢାቇળ㔚ሶㇱຠ࡮᧚ᢱ⎇ⓥળ, ᣂẟ‫ޔ‬ᣂẟᄢቇ, 2002.11.13(1) ᄢਭ଻ቇ‫ޔ‬ᷓ੗ਭ⟤ሶ‫ޔ‬ጤ↰ዷᐘ‫ޔ‬ጊᧄኡ, ࠬࡄ࠶࠲ߦࠃࠆዉ㔚ᕈ Re ㉄ൻ‛⭯⤑ߩ૞⵾,
CPM2002-116
Materials Research Society Fall Meeting, ࡏࠬ࠻ࡦ‫࡯࠲ࡦ࠮࡮ࡦ࡚ࠪࡦࡌࡦࠦ࡮ࠬࡀࠗࡂޔ‬,2002.12.2-6(1) Nobuyuki Iwata, Shinji Kuroda, Hiroki Okuyama, Hiroshi Yamamoto, SYNHESES OF C60 THINFILMS WITH THICKNESS OF NANO-SCALE, I3.30(2) Manabu Ohkubo, Kumiko Fukai, Kohji Matsuo, Nobuyuki Iwata, Hiroshi Yamamoto, INTERFACECONDUCTION BETWEEN CONDUCTIVE ReO3 THIN FILM AND NdBa2Cu3O6, Z5.7
╙ 14 ࿁ᣣᧄ MRS ቇⴚࠪࡦࡐࠫ࠙ࡓ, ᧲੩‫᧲ޔ‬੩Ꮏᬺᄢቇ㧔ᄢጟጊ㧕, 2002.12.20-21(1) Takayuki Kato, Souki Yamaguchi, Saliman Alsadoon, Nobuyuki Iwata and Hiroshi Yamamoto,
PHTHALOCYANINE DERIVATIVES LB FILMS ACCUMULATED ON ITO GLASSES, E2-P11-M(2) Kumiko Fukai, Manabu Ohkubo, Nobuyuki Iwata and Hiroshi Yamamoto, PREPARATION OF
CONDUCTIVE ReO3 THIN FILMS BY RF SPUTTERING, M2-P08-M

(3) Hiroyuki Imai, Yasuhiro Nishimura, Nobuyuki Iwata and Hiroshi Yamamoto, SYNTHESIS OF
C60-SAM ON Au ULTRATHIN FILMS, A1-P24-M
H15 ᐕ㔚᳇ቇળో࿖ᄢળ, ᧲ർቇ㒮ᄢቇ, 2003.03.19(1) ጊᧄ, ጤ↰, ᦭ᯏ⭯⤑෸߮᦭ᯏ࡮ήᯏⶄว⤑ߩᣂᯏ⢻⊒⃻ߣ࠺ࡃࠗࠬᔕ↪, ࠪࡦࡐࠫ࠙ࡓ 2S7-8╙ 50 ࿁ᔕ↪‛ℂቇ㑐ଥㅪว⻠Ṷળ, ␹ᄹᎹᄢቇᮮᵿࠠࡖࡦࡄࠬ, 2003.3.27-30(1) ᅏጊ, ጤ↰, ጊᧄ, C60 ⿥⭯⤑ߩૐᰴర࠽ࡁ᭴ㅧ, 28p-B-11(2) ᶏ⠧ᴛ, 㒸, ਛፉ, ጊਅ, ᰞᴛ, ጊᧄ, ᧻ේ, ዊဳࡄ࡞ࠬ▤಄ಓᯏߦ៞タߒߚ㜞᷷⿥વዉ࡚ࠫ࠮
ࡈ࠰ࡦធวߩࡁࠗ࠭․ᕈ, 29a-ZS-10(3) ੹੗, ዊᨋ, ᷡ᳓, ጤ↰, ጊᧄ, C60⺃ዉ૕⥄Ꮖ⚵❱නಽሶ⤑ߩ૞⵾ߣ㔚᳇વዉ․ᕈ, 29p-YN-12(4) ᷓ੗, ᄢਭ଻, ጤ↰, ጊᧄ, ReO3 ⭯⤑ߩ㔚᳇વዉᕈ, 27p-S-16(5) ട⮮, ጊญ, Saliman Alsadoon, ጤ↰, ጊᧄ, ၮ᧼ᐔṖᕈߩ㆑޿ߦࠃࠆࠕ࡜ࠠࠫࡦ㉄/ࡈ࠲ࡠࠪࠕ࠾
ࡦ⺃ዉ૕ᷙว LB ⤑ߩ㈩ะᐲᄌൻ, 28p-C-1
㔚ሶᖱႎㅢାቇળ SCE ⎇ⓥળ, ᯏ᪾ᝄ⥝ળ㙚, ᧲੩, 2003.04.
(1) ਛ᎑, ࿖ಽ, 㘸᧛, ጤ↰, ᮻ⼱, ↰ㄝ, ᫪ਅ, ጊᧄ, ోᎿ⒟ MOCVD ᴺߦࠃࠆ࡚ࠫ࠮ࡈ࠰ࡦធวߩ
૞⵾, SCE2003-2╙68࿁2003ᐕᐲᤐቄ ૐ᷷Ꮏቇ࡮⿥વዉቇળ, ↥ᬺᛛⴚ⎇ⓥᚲߟߊ߫࠮ࡦ࠲࡯ ౒ห⻠ၴ,
2003.05.21,22,23(1) ᰞᴛ, ዊᨋ, ጊᧄ, ౎චự, ᧻ේ, ⑺↰, ═ේ, ࡄ࡞ࠬ▤಄ಓᯏ↪ࠗ࠽࡯࠲ࡦࠬ࠴ࡘ࡯ࡉߩ๟ᵄ
ᢙ․ᕈ, 2C-a10
The 7th International Symposium on Sputtering & Plasma Processes, Kokusai Hotel, Kanazawa,
2003.06.11-13(1) H. Yamamoto, K. Fukai, K. Matsuo, N. Iwata, Optical and conductive properties of ReO3 sputtered thinfilms, TF 3-5╙ 25 ࿁ࡈ࡜࡯࡟ࡦ࡮࠽ࡁ࠴ࡘ࡯ࡉ✚วࠪࡦࡐࠫ࠙ࡓ, ᷆〝ᄞ⥰บ࿖㓙ળ⼏႐, 2003.07.23-25(1) Nobuyuki Iwata, Hiroki Okuyama, Akane Kinjo and Hiroshi Yamamoto, Low Dimensional Alignment of
C60 Molecules Prepared on Thermal Treated Substrates, 1P-57
㔚ሶᖱႎㅢାቇળ CPM ⎇ⓥળ, ✂⿛ࠣ࡜ࡦ࠼ࡎ࠹࡞, 2003.08.01(1) ᅏጊ, ㊄ၔ, ጤ↰, ጊᧄ, C60 ૐᰴర࠽ࡁ᭴ㅧ⿥⭯⤑ߩᒻᚑ, CPM2003-61╙64࿁ᔕ↪‛ℂቇળቇⴚ⻠Ṷળ, ⑔ጟᄢቇ৾㓊ࠠࡖࡦࡄࠬ, 2003.08.30- 09. 2(1) ᶏ⠧ᴛ, 㒸, ਛፉ, ጊਅ, ᰞᴛ, ጊᧄ, ᧻ේ, ዊဳࡄ࡞ࠬ▤಄ಓᯏࠍ↪޿ߚ㜞᷷⿥વዉ࡚ࠫ࠮ࡈ
࠰ࡦ㜞๟ᵄᬌ಴ࠪࠬ࠹ࡓ, 31a-ZS-10(2) ਛ᎑, ࿖ಽ, 㘸᧛, ጤ↰, ᮻ⼱, ↰ㄝ, ᫪ਅ, ጊᧄ, MOCVDᴺߦࠃࠆNdBa2Cu3O7-x࡜ࡦࡊࠛ࠶ࠫ
ធวߩ૞⵾, 2a-N-9(3) ㊁ญ, J. Kurian, 㘸᧛, ጤ↰, ᬮ, ↰ㄝ, ᫪ਅ, ጊᧄ, Ba2NdTaO6 ࡃ࠶ࡈࠔጀࠍ↪޿ߚ MgO ၮ᧼਄ߩ NdBa2Cu3O7-d ⭯⤑ߩ૞⵾ߣ⹏ଔ, 30a-K-11(4) ᷡ᳓, ᢧ⮮, ૒ਭ㑆, ጤ↰, ጊᧄ, C60 ⺃ዉ૕⥄Ꮖ⚵❱නಽሶ⤑ߩ㔚᳇વዉ․ᕈ, 2a-L-5(5) ᧻የ, ጤ↰, ጊᧄ, 㔚᳇⏛᳇ലᨐ⭯⤑૞⵾ߣߘߩᔕ↪, 30p-T-13(6) ᅏጊ, ㊄ၔ, ጤ↰, ጊᧄ, ၮ᧼ࠬ࠹࠶ࡊ᜛ᢔ㓚ოࠍ೑↪ߒߚ C60/㊄ዻߩૐᰴర࠽ࡁ᭴ㅧ,30a-YL-8(7) ᪊੗, ᷓ੗, ጤ↰, ጊᧄ, ReO3 ⭯⤑ߩ⚿᥏ᕈߣ㔚᳇વዉᕈ, 30p-ZA-2

(8) ጊญ, ട⮮, 㜞ᯅ, ጤ↰, ጊᧄ, ࠕ࡜ࠠࠫࡦ㉄/ࡈ࠲ࡠࠪࠕ࠾ࡦ⺃ዉ૕ᷙว LB ⤑ߩ⴫㕙ⷰኤ,
2a-L-6
The 5th Joint Seminar of China-Japanese Amity Universities, X’ian University of Technology, X’ian,
China, 2003.09.09(1) N. Iwata and H. Yamamoto, Synthesis of C60 Monolayer with One-Dimensional Nano-Structure
The 8th IUMRS International Conference on Advanced Materials (IUMRS-ICAM 2003), Pacifico
Yokohama, Conference Center, Yokohama, Japan, 2003.10.08-13(1) N. Iwata, H. Okuyama, A. Kinjo and H Yamamoto, One Dimensional Alignment of C60 Molecules
Prepared on Thermal Treated Substrates, A4-09-O07(2) T. Kato, S. Yamaguchi, A.Takahashi, N. Iwata, H.Yamamoto, Chromogenic Responses Induced byElectric Field in Phthalocyanine Derivative LB Films, B2-11-O05(3) A. Noguchi, J. Kurian, T. Amemura, K. Tanabe, T. Morishita, N. Iwata, H. Yamamoto, M. Kusunoki, M.
Mukaida, S. Ohshima, Preparation and Characterization of NdBa2Cu3O7-x / Ba2Nd TaO6 // MgO
multilayer films, B7-12-O07(4) K. Fukai, M. Masui, N. Iwata and H. Yamamoto, Conductive Properties of ReO3/SrCuO2 Bilayered Films,
B7-13-O04(5) Y. Shimizu, K. Saito, T. Sakuma, N. Iwata and H. Yamamoto, Electronic Transport Properties of C60
Derivative Self-Assembly Monolayer on Au Ultrathin Film, B7-13-O07(6) Y. Nakajima, H. Kokubun, T. Amemura, N. Iwata, Y. Tarutani, K. Tanabe, T. Morishita and H. Yamamoto,Preparation of Josephson Junctions by MOCVD films, B7-13-O10(7) N. Iwata, K. Matsuo and H Yamamoto, Preparations and Evaluations of Magneto-Electric Oxides /Superconductor Multilayers, B8-13-O15╙ 47 ࿁ℂᎿቇㇱቇⴚ⻠Ṷળ, ᣣᧄᄢቇℂᎿቇㇱ⦁ᯅᩞ⥢, 2003.11.19(1) 㐳ጊ, ᅏጊ, ጤ↰, ጊᧄ, ᦭ᯏ FET ࠍ⋡ᜰߒߚ C60/CaF2//Si(111)ߩⓍጀ⤑ᚑ㐳, ᧚ᢱ࡮‛ᕈㇱળCp38.
(2) ㊄ၔ, ᅏጊ, ጤ↰, ጊᧄ, ၮ᧼ࠬ࠹࠶ࡊࠍ೑↪ߒߚ Au ☸ሶߩૐᰴర࠽ࡁ᭴ㅧ, ᧚ᢱ࡮‛ᕈㇱળCp36.
(3) ᯅᧄ, ⍹Ꮉ, ጤ↰, ጊᧄ, 㜞࿶ਅ࡮శബ⿠ߦࠃࠆ C60 ࡐ࡝ࡑ࡯ߩวᚑ Cp37.
(4) ᫪ᧄ, ጤ↰, ᮻ⼱, ↰ㄝ, ጊᧄ, SFQ-dc ᄌ឵࿁〝ࠍߪߓ߼ߣߔࠆ SFQ ⷐ⚛࿁〝ߩ⸳⸘ߣࠪࡒࡘ࡟
࡯࡚ࠪࡦ, Cp41
(5) ᮘญ, ਛ᎑, ⧯⩿, ጤ↰, ቟㆐, ↰ㄝ, ጊᧄ, ⿥વዉ⭯⤑ߩ⤑⾰߇࡚ࠫ࠮ࡈ࠰ࡦធว․ᕈߦਈ߃ࠆᓇ㗀, Cp40(6) ᪊੗, ᷓ੗, ጤ↰, ጊᧄ, ReO3 ⭯⤑ߩ⚿᥏ᕈߣ㔚᳇વዉᕈߦਈ߃ࠆࠕ࠾࡯࡞ߩᓇ㗀, Cp39
(7) 㜞ᯅ, ട⮮, ጊญ, ጤ↰, ጊᧄ, ࠕ࡜ࠠࠫࡦ㉄/ࡈ࠲ࡠࠪࠕ࠾ࡦ⺃ዉ૕ᷙว LB ⤑ߩ㜞㈩ะൻߣశ
ๆ෼, Cp35╙ 69 ࿁ 2003 ᐕᐲ⑺ቄ ૐ᷷Ꮏቇ࡮⿥વዉቇળ,ፉᩮ⋵᳃ળ㙚, 2003.12.3,4,5(1) 㤥↰, ᰞᴛ, ౎චự, ᧻ේ, ጊᧄ, ᄙጀ⫾಄ེࠍ↪޿ߚዊဳࡄ࡞ࠬ▤಄ಓᯏߩ․ᕈ, 2C-a03(2) ᰞᴛ, 㤥↰, ዊᨋ, ጊᧄ, ౎චự, ᧻ේ, ⑺↰, ═ේ, ࠬ࠲࡯࡝ࡦࠣဳࡄࠬ࡞▤಄ಓᯏߩ⹜૞,2C-a02(3) ᷡ᳓, ጤ↰, ጊᧄ, ቶ᷷⿥વዉࠍ⋡ᜰߒߚ᦭ᯏಽሶ/㊄ዻ⿥⭯⤑⇇㕙, 2D-a06

㔚ሶᖱႎㅢାቇળ CPM ⎇ⓥળ, ንጊᄢቇᎿቇㇱ, 2003.11.10-11(1) ᅏጊ, ㊄ၔ, 㐳ጊ, ጤ↰, ጊᧄ, ౣ⫳⊒ᴺߦࠃࠆ C60 ⿥⭯⤑࠽ࡁ᭴ㅧ, CPM2003-137(2) ᷓ੗, ᪊੗, ጤ↰, ጊᧄ, ࠬࡄ࠶࠲ᴺߦࠃࠆ ReO3/SrCuO2 Ⓧጀ⤑ߩ૞⵾, CPM2003-138
2003 MRS FALL MEETING, Hynes Convention Center and Sheraton Boston Hotel, Boston, MA,
2003.12.01-05(1) N. Iwata, H. Okuyama, A. Kinjo and H. Yamamoto, One Dimensional Alignment of C60 Molecules
Prepared on Thermal Treated Substrates, O3.6
╙ 26 ࿁ࡈ࡜࡯࡟ࡦ࡮࠽ࡁ࠴ࡘ࡯ࡉ✚วࠪࡦࡐࠫ࠙ࡓ 2P-53, ጟፒࠦࡦࡈࠔ࡟ࡦࠬ࠮ࡦ࠲࡯,2004.01.07-09.
(1) ጤ↰, 㐳ጊ, ㊄ၔ, ᅏጊ, ጊᧄ, ᦭ᯏ FET ߳ะߌߚ C60/CaF2//Si(111)ߩ૞⵾
NSTI Nanotech(The Nanotechnology Conference and Trade Show), Sheraton Boston Hotel, Boston,MA, 2004.3.07-11(1) H. Yamamoto, N. Iwata and Y. Shimizu, Nano-Structured C60-SAM Formed on Ultrathin Au Films/MgOSingle Crystal, TU57.01╙ 51 ࿁ᔕ↪‛ℂቇ㑐ଥㅪว⻠Ṷળ, ᧲੩Ꮏ⑼ᄢቇ, ౎₺ሶ㧘2004. 03.28-31(1) ⇌, ጤ↰, ጊᧄ, 㔚ሶ✢ᾖ኿ဳ᦭ᯏ⊒శ⚛ሶߩ⊒శኼ๮ߩᬌ⸛, 28p-ZR-6(2) ጊญ㧘ട⮮㧘㜞ᯅ㧘ጤ↰㧘ጊᧄ㧘ࡈ࠲ࡠࠪࠕ࠾ࡦ⺃ዉ૕ᷙว LB ⤑ߩ㜞㈩ะൻߣశๆ෼․ᕈ㧘
29p-ZR-10(3) ᪊੗㧘ᷓ੗㧘ጤ↰㧘ጊᧄ, ReO3 ⭯⤑ᚑ㐳ߦਈ߃ࠆࠕ࠾࡯࡞㔓࿐᳇ߩᓇ㗀, 30p-P16-18(4) ૒ਭ㑆, ᷡ᳓, ᢧ⮮, ጤ↰, ጊᧄ, Au ⿥⭯⤑਄ C60 ⺃ዉ૕⥄Ꮖ⚵❱නಽሶ⤑ߩ૞⵾ߣ㔚᳇વዉ․ᕈ, 29a-ZF-11 Υ(5) ⍹Ꮉ, ᯅᧄ, ጤ↰, ጊᧄ, ⥄↱㔚ሶ࡟࡯ࠩ࡯ߦࠃࠆ 3 ᰴర C60 ࡐ࡝ࡑ࡯ߩวᚑ, 30p-ZW-10(6) ᄢႦ㧘ጤ↰㧘ጊᧄ, 㔚᳇⏛᳇ലᨐ⭯⤑૞ᚑߣߘߩ⹏ଔ, 30-YF-8
MRS Spring Meeting IUMRS-ICEM 2004, Moscone West, San Francisco, USA, 2004.04.12-16(1) H. Okuyama, A. Kinjo, Y. Nagayama, N. Iwata, and H. Yamamoto, Low-Dimensional Nano-Structures of
C60 Ultrathin Films by Re-Evaporation Method, T5.11(2) H. Yamamoto, N. Iwata, and Y. Shimizu, Resistivity Anomaly Observed at Interfaces of C60 Derivatives
self-assembly Monolayer/Ultrathin Au Films, T5.29(3) N. Iwata, K. Matsuo, N. Ootsuka, and H. Yamamoto, Preparations and Evaluations of MagnetoelectricThin Films for Josephson Field Effect Transistor, E3.6
2004 International Symposium on Organic and Inorganic Electronic Materials and Related
Nanotechnologies (EM-NANO 2004), Toki Messe, Niigata, Japan, 2004.06.07-10(1) H. Hata, N. Iwata, and H. Yamamoto, Electron Beam Excited Light Emission Organic EL Thin Films,
P-44(2) S. Yamaguchi, K. Katayama, T. Hashimoto, N. Iwata, and H. Yamamoto, Optical Absorption of Highly
Oriented Pc Derivatives / Arachidic Acid Mixtured LB Films, P-86
(3) N. Iwata, A. Kinjo, H. Okuyama, and H. Yamamoto, Preparations and Evaluations of C60 Thin Films for
Organic-FET, O-A12(4) A. Kinjo, H. Okuyama, N. Iwata, and H. Yamamoto, Preparation and Transport Properties ofNano-Structured C60 Thin Films, P-151

(5) M. Masui, A. Matsumura, N. Iwata, and H. Yamamoto, Synthesis and Transport Properties of
ReO3/SrCuO2 Bilayered Films, P-102(6) N. Iwata, T. Sakuma, and H. Yamamoto, Resistivity Anomaly Above 100K in C60 Derivatives
Self-Assembly Monolayer on Ultarathin Au, P85(7) T. Ishikawa, R. Hashimoto, N. Iwata, and H. Yamamoto, Synthesis of C60 Polymer by Irradiation of Free
Electron LASER, P-7(8) N. Ootsuka, N. Iwata, and H. Yamamoto, Preparation of Magneto-Electric Oxide / YBa2Cu3Ox Thin
Films by Sputterring, P-101╙ 27 ࿁ࡈ࡜࡯࡟ࡦ࡮࠽ࡁ࠴ࡘ࡯ࡉ✚วࠪࡦࡐࠫ࠙ࡓ, ᧲੩ᄢቇᱞ↰ࡎ࡯࡞, 2004.07.28-30(1) ㊄ၔ, ᅏጊ, ጤ↰, ጊᧄ, C60 ಽሶߩ࠽ࡁ᭴ㅧ૞⵾ߣ㔚᳇વዉ․ᕈ, 3P-15(2) ૒ਭ㑆㧘ጤ↰㧘ጊᧄ㧘Resistivity Anomaly of Self-Assembly Monolayer of C60 Derivatives on
Ultorathin Au films㧘3P-16(3) ᯅᧄ, ⍹Ꮉ, ጤ↰, ጊᧄ, ⥄↱㔚ሶ࡟࡯ࠩ࡯ᾖ኿ߦࠃࠆ C60 ࡐ࡝ࡑ࡯ߩวᚑ, 3P-20
㔚ሶᖱႎㅢାቇળ㔚ሶㇱຠ࡮᧚ᢱ⎇ⓥળ, ጤᚻᄢቇᎿቇㇱ, 2004.08.06(1) ᅏጊ, ㊄ၔ, ᵻ੗, ဈᧄ, ጤ↰, ጊᧄ, න⚿᥏ၮ᧼਄ߦᒻᚑߐࠇߚ࠽ࡁ᭴ㅧࡈ࡜࡯࡟ࡦ㓸ว૕,
CPM2004-45
ELEVENTH ANNUAL INTERNATIONAL CONFERENCE ON COMPOSITES / NANO
ENGINEERING (ICCE-11), Hilton-Head Island, South Carolina, USA, 2004.08.08-14(1) N. Iwata, A. Kinjo, H. Okuyama, and H. Yamamoto, FABRICATION OF NANO-STRUCTURE BY C60
MOLECULES, Session 10a NANO10
Ninth International Conference on Ferrites (ICF9), Cathedral Hill Hotel, San Francisco, California,
USA, 2004.08.22-27(1) N. Iwata, N. Ootsuka, and H. Yamamoto, Preparation of Magneto-Electric Oxides / YBa2Cu3OX Thin
Films, ICF9-HA-6-2004╙ 65 ࿁ᔕ↪‛ℂቇળቇⴚ⻠Ṷળ㧘᧲ർቇ㒮ᄢቇ㧘ᴰࠠࡖࡦࡄࠬ㧘2004.09.01-04(1) ૒ਭ㑆, ᣇ, ᢧ⮮, ጤ↰, ጊᧄ, C60 ⺃ዉ૕ SAM/Au ⿥⭯⤑⇇㕙ߩ㔚᳇વዉ⇣Ᏹ, 2a-A-14/I(2) ᮘญ㧘ਛ᎑㧘⧯⩿㧘቟㆐㧘ጤ↰㧘ጊᧄ㧘↰ㄝ㧘㜞᷷⿥વዉ࡜ࡦࡊࠛ࠶ࠫဳ࡚ࠫ࠮ࡈ࠰ࡦធว૞
⵾ߦ߅ߌࠆ਄ㇱ㔚ᭂᒻᚑ᧦ઙߩᬌ⸛㧘2a-F-5
European Materials Research Society (E-MRS) 2004 Fall Meeting, Warsaw University of Technology,
Warsaw, Poland, 2004.9.6-10(1) N. Iwata, M. Masui, A. Muramatsu, and H, Yamamoto, Transport Properties at Interfaces between
Conductive Oxide ReO3 and Cuprate Superconductors, Poster E-9(2) N. Iwata, T. Sakuma, T. Fanj, and H. Yamamoto, Resistivity Anomaly Observed in Nano-Structured
C60-SAM on Ultrathin Au Films
IUMRS-International Conference in Asia(ICA)2004, Industrial Technology Research Institute(ITRI),
Hsinchu, Taiwan, 2004.11.16-18(1) H. Yamamoto, N. Iwata, and T. Sakuma, Electronic Transportation Anomaly Observed in Interfaces ofNanostructured C60 Monolayers and Ultrathin Au Films (Invited Paper: Symposium A, I-12)╙ 15 ࿁ᣣᧄ MRS ቇⴚࠪࡦࡐࠫ࠙ࡓ, ᣣᧄᄢቇℂᎿቇㇱ㧔㛁ᴡบᩞ⥢㧕, 2004.12.23-24

(1) ⇌, ጤ↰, ጊᧄ, Bright Luminescence from Organic EL Thin Films by Electron Beam Irradiation,
B1-P09-M(2)ጊ㧘ጊญ㧘ᯅᧄ㧘ጤ↰㧘ጊᧄ㧘Absorption Spectrum of Phthalocyanine Derivatives LB Films,
B1-P06-M(3) ㊄ၔ㧘ᅏጊ㧘ጤ↰㧘ጊᧄ㧘Nano-Structured Alignment of C60, B1-P02-M(4) ᯅᧄ㧘⍹Ꮉ㧘ጤ↰㧘ጊᧄ㧘Synthesis of C60 Polymer by Irradiation of Free Electron Laser㧘Q2-P19-M(5) ᄢႦ, ጤ↰, ጊᧄ, Preparation of Magneto-Electric Oxide / YBa2Cu3Ox Thin Films by Sputterring,
Q2-P21-M

Surface and Coatings Technology 169 – 170 (2003) 646–649

Transport properties of C60 ultra-thin films
Nobuyuki Iwata*, Keigo Mukaimoto, Hiroyuki Imai, Hiroshi Yamamoto
Department of Electronics and Computer Science, College of Science and Technology, Nihon University, 7-24-1 Narashinodai, Funabashi-shi,
Chiba 274-8501, Japan

Abstract
We have grown the C60 ultra-thin films on natural mica substrates aiming at nano-scale devices. Whereas, the appearance ofthe high temperature superconductivity in hole-induced C60 bulk single crystal and CHBr3 intercalated C60 bulk by the field effecthave attracted extensive attention. From the viewpoints of nano-scale devices and superconductivity, we grew single crystal thinfilms, those were grown on the buffer layer (5 nm thickness) of the C60 ultra-thin films. We concluded that the optimized C60
film was a single crystal with quite-thin thickness on the buffer layer for nano-scale devices and appearance of superconductivity.
䊚 2003 Elsevier Science B.V. All rights reserved.
Keywords: Single crystal; C60 thin film; Buffer layer; Field effect; Superconductivity

1. Introduction
Nano-scale devices are promising for future technologies, for example, organic-based molecules are orderedalong 1D andyor 2D w1–3x. In our previous studies,
C60 ultra-thin film less than 10 nm thickness has been
overspread continuously on mica substrates for nanoscale devices w4x.
Whereas, the high-Tc superconductivity was observedin bulk C60 and CHBr3-C60 single crystals, recently, byapplying the electric field in order to induce the holecarriers with a FET configuration w5,6x. The value of
the Tc is almost same to that of the highest Tc of oxides
superconductors.
For appearance of the high-Tc of the C60 thin films,
the films are preferable to be highly oriented, namely
single crystal. In this study we reported single crystal
C60 thin films and the relation between continuous C60
ultra-thin films, obtained in previous studies, and single
crystal C60 thin films.
2. Experimental procedures
We grew C60 thin films in a UHV-MBE system with*Corresponding author. Tel.: q81-47-469-5457; fax: q81-47-4679683.
E-mail address: iwata@ecs.cst.nihon-u.ac.jp (N. Iwata).

a background pressure of 1=10y8 Torr. A cleaved
natural mica substrate was set on the sample holder,
where copper foil with 0.01 mm thickness was inserted
between the holder and substrate for a better thermal
contact and temperature uniformity. Prior to deposition
the substrate was prebaked at 400 8C for 60 min in
vacuum. The temperature of a substrate was measured
by an optical pyrometer. The C60 powder with 99.9%
purity was evaporated from PBN crucible in an effusion
cell. The cell temperature was varied approximately 310
8C while growing in order to evaporate the specific
C60 flux rate by monitoring with a crystal thickness
monitor. The growth time was 30 min without exception.
3. Results and discussion
AFM images with 2 mm2 are described in Fig. 1 atvarious temperatures, indicated at upper left of theimages. The grains with 50 nm ⭋ were spread in thefilm surface grown at (a) 40 8C. As the substratetemperature increased, the grain size also increased. In(b) 80 8C, the size of the grains were 150 nm ⭋, andthe part of those grains formed triangle. In (c) 100 8C,
the triangle structure was clearly seen, and the size ofthat was increased with increasing substrate temperature
up to 120 8C. Each grain was separated distinctly by
the grain-boundaries. Above approximately (d) 120 8C,
the triangle-shaped grains began to coalesce and be re-0257-8972/03/$ - see front matter 䊚 2003 Elsevier Science B.V. All rights reserved.
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N. Iwata et al. / Surface and Coatings Technology 169 – 170 (2003) 646–649

647

steps and terraces structure were observed in (f) 170
8C. In (g) 190 8C, evident 60 and 1208 facets and theterraces with a large size were obtained. The grainboundary from the upper left to lower right was expectedfrom steps of the substrate occurred when the substrate
was cleaved. At (h) 200 8C, clearer steps and larger
terraces were obtained. In some places on a substrate,
no film was obtained, indicating that the re-evaporationof C60 molecules took place at such a higher substratetemperature. Above (f) 170 8C, the height of the step
was almost same to that of lattice spacing of C60(1 1 1),
˚ The result revealed that the direction of the
8.16 A.
C60(1 1 1) was normal to the substrate surface. Above(f) 170 8C, the higher the substrate temperature was,the larger terrace size of the top at the each grain was.
Increasing of the re-evaporation effect caused the differences of such a surface morphology. Consequently, 2D
film was obtained with micrometer-ordered-grains at thehigher substrate temperature, where re-evaporation took
place, remarkably.
Arrhenius plot of the average radius of the grains is
illustrated in Fig. 2 assuming that the shape of grains is
circle. The straight line fitted the plots. The value of
0.21 eV as activation energy was estimated from theslope of the straight line. The beautiful fitting indicatedthat C60 crystallized according to the simple model inthe whole range of substrate temperatures, and that C60
molecules migrated to comfortable positions by overcoming the barrier caused by the van-der-Waals force.
From the XRD results, the full width at half maximum(FWHM) of C60(1 1 1) Bragg peak and intensity of thepeak are illustrated as a function of substrate temperatures as shown in Fig. 3. The FWHM decreased rapidly
up to approximately 100 8C, and then showed constantvalue. As the fluctuation of the lattice spacing, especiallyperpendicular to the substrate surface, is decreasing,namely as the substrate temperature is increasing, thevalue of the FWHM for Bragg peak should be decreas-

Fig. 1. AFM images with 2 mm2 grown at various substrate temperatures. The size of the triangle-shaped grains were increasing withincreasing temperature, and then began to coalesce approximately 120
8C. Above 170 8C, the height of the step was almost same to the
˚ In addition to re-orientation inlattice spacing of C60(1 1 1), 8.16 A.
coalesced grains, re-evaporation took place, remarkably, at higher substrate temperature. Consequently 2D films were obtained, demonstrated 60 and 1208 facets and larger terraces.

oriented in the coalesced grains. The triangle-shaped
grains were no longer present at (e) 150 8C. From theresult of coalescence and re-orientation of the grains,

Fig. 2. Arrhenius plot of the average radius of the grains. The straightline fitted well the plots. The value of 0.21 eV as activation energy
was estimated.

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N. Iwata et al. / Surface and Coatings Technology 169 – 170 (2003) 646–649

Fig. 5. A schematic view of the specimen configuration for field effectmeasurements. Tentative electrode sizes are shown in the figure, andthe length of those was 5 mm. The thickness of the substrate as agate insulator layer was 10 mm-order.
Fig. 3. Substrate temperature dependence of the FWHM of theC60(1 1 1) Bragg peak in left vertical axis and of the intensity of thepeak in the right vertical axis.

ing. Whereas, as the film thickness is thinner by the reevaporation, the value of FWHM becomes larger.
Addition of those two effects appeared in the FWHM
behavior observed. Same consideration was applicableto the behavior of the intensity of the C60(1 1 1) Braggpeak.
As shown in Fig. 4, the film was grown at 190 8C
for 5 min. Substrate surface was clearly seen in thebottom of the image. The 2D islands with thickness of
5"0.5 nm, namely ultra-thin film, were observed aroundthe center of the image. The step and terrace structuresappeared in the top of the image. This image indicatedthat the single crystal C60 thin film grew on the ultrathin film, namely the buffer layer. The difference of thesurface image was expected to attribute to the substratetemperature distribution or the substrate steps indicatedby the arrows, which accelerate the nucleation.
Generally, the film growth is affected by substratesurfaces. However, in the case of C60 film growth, thesubstrate effect was expected to be completely reduced
due to the existence of the buffer layer. In such a growth
condition, film grew according to the simple model, as
discussed in Fig. 2, and then close-packed, fcc, structure
seemed to be realized.
We concluded that the suitable C60 films for nanoscale devices and FET-superconductivity were single
crystal C60 ultra-thin films grown on the buffer layer
with 5 nm.
We tried to study the electric field effects of suchsingle crystal C60 thin films on the buffer layer as shownin Fig. 5 with the tentative size. The electrode length
was approximately 5 mm. After the deposition of the
C60 thin film and Al electrodes (source and drain) insitu, the substrate was exposed to the air and thencleaved with 10 mm-order thickness. Then the substrate
was working as a gate insulator. The gate Al electrodewas deposited back of the film surface. The resistance
between source and drain was too high to measure atroom temperature and 77 K. Such a situation did notchange when the gate voltage was applied up to "350V.
4. Conclusion
Highly oriented single crystal C60 thin films grew on
mica substrates with 5 nm buffer layer just below thesubstrate temperature, where C60 molecules re-evaporated. The direction of the C60(1 1 1) was normal to thesubstrate surface. Such a film was suitable for nanoscale devices and an appearance of a FETsuperconductivity.
Acknowledgments

Fig. 4. The AFM image with 5 mm2 of the film grown at 190 8C for
5 min. The arrows indicated the grain boundary attributed from substrate steps.

The authors are grateful for the financial support of
the Grant-in-Aid for Scientific Research (No.
12650322).

N. Iwata et al. / Surface and Coatings Technology 169 – 170 (2003) 646–649

References
w1x P.W. Murray, I.M. Brookes, S.A. Haycock, G. Thornton, Phys.
Rev. Lett. 80 (1998) 988.
w2x C. Zeng, B. Wang, B. Li, H. Wang, J.G. Hou, Appl. Phys.
Lett. 79 (2001) 1685.

649

w3x M. Bohringer,¨
K. Morgenstern, W.D. Schneider, et al., Phys.
Rev. Lett. 83 (1999) 324.
w4x N. Iwata, N. Hashimoto, H. Yamamoto, Mater. Res. Soc. Jpn.
26 (2001) 1339.
w5x J.H. Schon, Ch. Kloc, B. Batlogg, Nature 408 (2000) 549.
w6x J.H. Schon, Ch. Kloc, B. Batlogg, Science 293 (2001) 2432.

Transport properties of C60 thin ﬁlms
Nobuyuki Iwata, Shinji Kuroda, Hiroki Okuyama
and Hiroshi Yamamoto
Presented at the 8th International Conference on Electronic
Materials (IUMRS-ICEM 2002, Xi’an, China, 10–14 June
2002)

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Advanced Nanomaterials and Nanodevices (IUMRS-ICEM 2002, Xi’an, China, 10–14 June 2002)

Transport properties of C60 thin films
Nobuyuki Iwata, Shinji Kuroda, Hiroki Okuyama and Hiroshi Yamamoto

Department of Electronics & Computer Science, College of Science & Technology,
Nihon University, 7-24-1 Narashinodai, Funabashi-shi, Chiba 274-8501, Japan

We investigated the differences of growth mechanism and electric properties for C60
thin films on natural mica and SrTiO3 substrates with and without vacuum ultraviolet
radiation while growing for the future nano-scale devices. Whereas, electric propertiesof C60 thin films are also attracted from the point of FET-superconductivity, recently.
Highly oriented epitaxial C60 thin films with hcp structure grew at the temperature justbelow 200 °C, of which surface was 2-dimmentionaly flat and showed 60 and 120
degrees facets. At that temperature the surface roughness Ra was 0.6 ( ± 0.2 ) nm. No
apparent differences were detected with and without vacuum ultraviolet radiation.
Resistance was too high to detect it with applying the voltage in the FET construction.

Keywords : C60 thin film, mica substrate, epitaxial growth, re-evaporation,

INTRODUCTION
One-dimensional (1D) and/or two-dimensional (2D) ordering of organic-based
molecules have attracted the attention for the future nano-scale devices with theself-assembled manner[1-3]. We chose C60 molecules as organic material because of its
novel physical and electrical properties. However, electric properties of C60 vary underoxygen atmosphere with light radiation. In this study we investigated the differences ofgrowth mechanism and electric properties for C60 thin films with and without vacuum
ultraviolet radiation while growing[4]. Electric properties of C60 thin films are also
attracted from the point of FET-superconductivity, recently[5].

701Advanced Nanomaterials and Nanodevices (IUMRS-ICEM 2002, Xi’an, China, 10–14 June 2002)

EXPERIMENTAL PROCEDURES
We grew C60 thin films in a UHV-MBE system with a background pressure of lessthan 1×10-8 Torr. Main-chamber for film growth and pre-chamber for sample exchange
were evacuated by a 2000 l / s diffusion pump and a 220 l / s turbo molecular pump,
respectively. The pressure while growing was 2.5 ( ± 0.5) × 10-8 Torr.
A cleaved natural mica substrates and SrTiO3 substrates were set on the sample holder
and were prebaked at 400 ºC for 60 min and 700 ºC for 30 min, respectively. The
temperature of a substrate (TS) was measured by an optical pyrometer through the
viewport specially equipped with a ZnSe window.
C60 powder with 99.9 % purity was evaporated from PBN crucible in an effusion cell.
The cell temperature was varied while growing in order to evaporate the constant C60
flux rate by thickness monitor. The growth time was 30 min. A 90 nm thick film wasdeposited on glass substrate at room temperature.
Vacuum ultraviolet light was radiated by a heavy hydrogen lamp (HAMAMATSU :L1835-150W, C3150) at intervals of 65 cm away from substrate.
Grown films were evaluated by XRD (Rigaku : RAD-C) and AFM (Seiko Instruments
Inc. SII : SPI3800).

RESULTS AND DISCUSSION
Fig.1(a) and Fig.1(b) showed the 2θ-θ XRD spectrum of C60 thin films grown at
186 °C on mica substrate with vacuum ultraviolet radiation and mica substrate,
respectively. Bragg reflections of the C60 hcp structure indicated the epitaxial growthon mica substrate. Other reflections were from the substrate confirmed by Fig.1(b).
Similar Bragg peaks were obtained at all substrate temperature, independent of theradiation. No film remained at the temperature above 200 °C due to the re-evaporationof C60 molecules. The lattice spacing of C60(002), fitted by Nelson-Riley function, was
0.817 ± 0.001 nm, similar to that of hcp bulk, 0.818 nm.
Fig.2 shows the substrate temperature dependence of full width at half maximum,
FWHM, of C60(002) Bragg reflection. The FWHM decreased up to 80 °C, and showed702

Advanced Nanomaterials and Nanodevices (IUMRS-ICEM 2002, Xi’an, China, 10–14 June 2002)

the constant value at the temperature range from 80 °C and 180 °C. Above 180 °C, thevalue rapidly increased.
Generally, the FWHM of 2θ-θ Bragg reflection depends on the fluctuation of thelattice spacing and the film thickness.

As the fluctuation was decreasing withincreasing temperature, the FWHM should be reduced, whereas with increasing
temperature film thickness became thinner by the re-evaporation, the FWHM should be
increasing. These two origins led to the behavior of the FWHM against substratetemperature.
Figs.3 show the AFM images of the C60 thin films grown above 149 °C on mica
substrates without vacuum ultraviolet radiation. At all of the images, the step andterraces were clearly observed. With increasing temperature, the terrace width became
larger.

At 149 °C, Figs.3(a-1,-2), numbers of the grains with spiral growth wereobserved, indicating the 3D growth mode. At 185 °C, Figs.3(b-1,-2), the separated
grains were not obvious, and the spiral growth was obtained in some places on the 2Dflat foundation C60 thin film, indicating the 3D growth on 2D. At 197 °C, Figs.3(c-1,-2,
and -3), there were no spiral growth, just steps and terraces and 60 and 120 degrees facets
appeared. It looked like the 2D growth mode. Above this temperature, no film and no
AFM images were obtained due to the re-evaporation.
It was noted that the growth mode looked like changing with increasing temperature.
However, above 185 °C, at which re-evaporation was an effective, C60 molecules at themountaintop of the spiral growth should re-evaporate first. Eventually, the different
surface obtained was caused by not the difference of the growth modes but there-evaporation.
In Fig.4, the line profile of the Fig.3(c-1) is described. Step height of 0.8 nm wasperfectly consistent with the lattice spacing of (002) for C60 hcp bulk structure.
Temperature dependence of the surface morphology for the films with radiation wasalmost same to that of the films without radiation. Altogether, it was more difficult to
detect the fine images than those of the films grown without radiation, expected fromstatic electricity.

703

Advanced Nanomaterials and Nanodevices (IUMRS-ICEM 2002, Xi’an, China, 10–14 June 2002)

Surface roughness Ra is illustrated as a function of substrate temperature in Fig.5.
The Ra decreased linearly with increasing temperature up to 150 ºC, and then showed therapid fall to the lowest point. The rapid decreasing was consistent with the difference ofgrowth modes, demonstrated in the difference of the AFM images between Fig.3(a) and
Figs. 3(b,c).
On the SrTiO3 substrates, no oriented films were obtained from 135 ºC to 190 ºC
without radiation, confirmed by RHEED and AFM.
For electric measurement, we constructed the FET structure. However, the resistance
was too high to detect it with applying the voltage.

CONCLUSIONSAs demonstrated in Fig.1(a), Figs.3(c), and Fig.4, highly oriented epitaxial films grewat the temperature just below 200 °C. Growth mode changed from 3D to 3D on 2D
above 150 °C, and then 2D surfaces were obtained because of the re-evaporation, see
Figs.3 and Fig.5. From the XRD results and AFM images, no apparent difference was
detected with and without vacuum ultraviolet radiation.

References[1] C. Zeng, B. Wang, B. Li, H. Wang, and J. G. Hou : Appl. Phys. Lett. 79 (2001) 1685.
[2] P. W. Murray, I. M. Brookes, S. A. Haycock, and G. Thornton : Phys. Rev. Lett. 80(1998) 988.
[3] M. Böhrnger, K. Morgenstern, W. D. Schneider, R. Berndt, F. Mauri, A. D. Vita, and
R. Car : Phy. Rev. Lett. 83 (1999) 324.
[4] N. Iwata, K. Mukaimoto, H. Imai and H. Ymamoto : Sur. Coat. Tech. will be
published.
[5] J. H. Schön, C. Kloc, and B. Batlogg : Science 293 (2001) 2432.

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Advanced Nanomaterials and Nanodevices (IUMRS-ICEM 2002, Xi’an, China, 10–14 June 2002)

Figure captions
Figure 1 : (a) XRD 2θ-θ spectrum of C60 // natural mica substrate grown at 186 °C withvacuum ultraviolet radiation.

(b) XRD 2θ-θ spectrum of natural mica

substrate.
Figure 2 : Substrate temperature dependence of the FWHM of C60(002) Bragg reflection
without (٤) and with (‫ )غ‬radiation.
Figure 3 : AFM images of C60 // natural mica substrate grown above 149 °C without
vacuum ultraviolet radiation. The size of the upper images was 2μm2 and of
the lower images was 5μm2.
Figure 4 : Line profile of the Fig.3(c-1).
Figure 5 : Substrate temperature dependence of the surface roughness Ra of C60 // natural
mica substrate without (2μm2 : ٤, 5μm2 : ٨) and with (2μm2 : ‫غ‬, 5μm2 :‫ )ع‬radiation.

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Thin Solid Films 383 Ž2001. 89᎐91

Low-voltage electron beam excitement luminescence of oxidethin ﬁlms with multilayered structure
H. YamamotoU , H. Isogai, Y. Yoshida
College of Science and Technology, Nihon Uni¨ ersity, Funabashi-shi, Chiba 274-8501, Japan

Abstract
A greenish-blue light emission was observed in sputtered ﬁlms that were deposited on 773-K substrates from a ZnGa 2 O4target. The ﬁlms prepared were amorphous and had a bilayer structure with a compositional modulation formed by self-assembly.
The approximately 2-nm surface layers thick were Zn-rich, and the inner layers Ga-rich, in the 40-nm thick ﬁlm. As the ﬁlm
thickness increased, the strength of the light emission increased and saturated at approximately 60 nm. The strength of thelight-emission intensity revealed a maximum at approximately 200 V for the acceleration voltage. In the case of artiﬁcial
bilayered ZnOrNiO ﬁlms, continuous ultrathin surface layers were not easily obtained, and no light emissions were observed.
䊚 2001 Elsevier Science B.V. All rights reserved.
Keywords: Cathodeluminescence; Zn᎐Ga᎐O; Thin ﬁlm; Bilayer; Self-assembly

1. Introduction
A ﬁeld emission display ŽFED. has been developed
as a future emissive display realizing high resolution
and low consumption of electric power w1x. Phosphorsin the FED need to have a low resistivity, no release ofpollutant gas, a highly efﬁcient emission of light, andstabilization of the surface.
Phosphor-type thin ﬁlms are expected to have several features: little restriction of resistivity, comparatively stable surfaces, and easy synthesis of a multilayered structure w2x. A system of Zn᎐Ga᎐O w3x was
focussed on as a basic phosphor material in this work.
The purpose of the work was to prepare a new type ofphosphor thin ﬁlm and to investigate the possibility for
improvement of light-emission efﬁciency by adopting
the multilayered structure.
2. Experimental
Prepared ﬁlms should be evaluated without exposure
U

Corresponding author.

to the atmosphere, because the surfaces of FED phosphor thin ﬁlms are so sensitive to electron excitation.
Thus, a new vacuum system was constructed in order toprepare thin ﬁlms by sputtering and to analyze in situ
cathodeluminescence properties andror the crystal
structure of the ﬁlm. The details of the vacuum system
are described elsewhere w4x.
Fig. 1 shows a schematic of the vacuum system usedin this work. Zn᎐Ga᎐O thin ﬁlms were prepared byreactive RF sputtering. The targets used were powder
mixtures with a diameter of 40 mm. The sputtering gas
was a mixture of Ar and O 2 . The total gas pressure was
20 mtorr and the sputtering power was 200 W. The
distance between the target and the substrates wasapproximately 30 mm. Typical deposition rates werevery small, approximately 10 nmrh. ITO glass was usedas the substrate, which was heated to a maximum of
approximately 900 K during deposition.
Measurement of the cathodeluminescent propertiesof the ﬁlms was according to the following procedure.
After in situ transfer of the specimen ﬁlm, vacuum
ﬂuorescence device ﬁlaments were moved towards theﬁlm surface by a manipulator. Thermal electrons emitted from the ﬁlaments were accelerated by an anode up

0040-6090r01r$ - see front matter 䊚 2001 Elsevier Science B.V. All rights reserved.
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H. Yamamoto et al. r Thin Solid Films 383 (2001) 89᎐91

90

Fig. 1. Schematic diagram of the vacuum system used for sputtering ﬁlm preparation and in situ measurement of cathodeluminescence.

to 700 V. The cathodeluminescence generated was
guided to a spectrometer ŽHamamatsu Photonics K. K.,
C5966-11. through a hemisphere lens of 2 mm diameter andror an optical ﬁber.
The ﬁlm surface structure was studied in situ by
reﬂected high-energy electron diffraction ŽRHEED.
andror the crystal structure was analyzed by reﬂected
X-ray diffraction ŽXRD.. The depth proﬁle of the ﬁlm
composition was investigated by X-ray photoelectron
spectroscopy ŽXPS..
3. Results and discussion
Thin ﬁlms of the Zn᎐Ga᎐O system were preparedfrom a ZnGa 2 O4 target. The ﬁlms appeared to beamorphous from the results of RHEED andror XRD.
The surface of the ﬁlm was smooth and ﬁne particles ofapproximately 60 nm were observed.
It was conﬁrmed from the XPS depth proﬁles that
Zn-rich surface layers and Ga-rich inner layers wereformed by self-assembly in the ﬁlms deposited onhigh-temperature substrates. The thickness of the Znrich layer was approximately 2 nm in the case of the; 40-nm thick ﬁlm. The ﬁlm deposited on ambient
temperature substrates showed almost stoichiometry.
The ﬁlm deposited on 773-K substrates revealed
cathodeluminescence in the form of a greenish-bluelight emission. No light emission was, however, observedin the ﬁlms prepared on low-temperature substrates.
Fig. 2 shows the peak intensities of the light emission
as a function of the thickness of the ﬁlm. Here, the two
types of ﬁlm deposition were investigated. As the ﬁlm
thickness increased, the strength of the light emission
increased and saturated at approximately 60 nm incontinuously deposited ﬁlms. The light emission intensity showed, however, a maximum in the ﬁlm preparedby four repetitions of 1-h deposition, approximately 10
nm thick.
A typical spectrum of the cathodeluminescenceobserved is inserted in Fig. 2. The light emission of the
ﬁlm was similar to that of ZnO rather than that of
ZnGa 2 O4 . The half-width of the peak was wider thanthat of ZnO.
Fig. 3 shows the light emission intensity as a functionof acceleration voltage Va . The intensity attained amaximum at approximately 200 V and decreased withincreasing Va . Enhancement of the light emission took
place in the bilayered structure.
These results with respect to thickness andror Va
dependence revealed that the light emissive region wasstrongly restricted near the surface of the bilayered
thin ﬁlms. The penetration depth of excited electrons
and the diffusion region become large with increasing
electron energy. The value of Va s 200 V gives a verysmall penetration depth, of the order of 1 nm. Theband gap of surface layers is comparatively smaller
than that of inner layers. This is the case of a quantum
well potential structure, where carriers involved in lightemission are enclosed near the boundary of the bilayers. Thus, an enhancement mechanism for light emission may be available in that region.
On the other hand, an artiﬁcial multilayered deposition was also carried out in a ZnOrNiO thin ﬁlm
system with various thickness of ZnO layers. However,no light emissions were observed in the ﬁlms. Continuous surfaces were not as easily obtained in such artiﬁcial bilayered ﬁlms.
4. Conclusion
Zn᎐Ga᎐O thin ﬁlms andror bilayered ﬁlms of

H. Yamamoto et al. r Thin Solid Films 383 (2001) 89᎐91

91

Fig. 2. Intensity of cathodeluminescence peaks of Zn᎐Ga᎐O ﬁlms by the two types of deposition process as a function of deposition time. The
inserted ﬁgure shows the typical cathodeluminescence spectrum of the ﬁlm.

ZnOrmetal oxide were prepared by sputtering. Only
the ﬁlms deposited on 773-K substrates from the
ZnGa 2 O4 target revealed greenish-blue light emissions.
The ﬁlms were amorphous and had a characteristic
bilayered structure with a compositional modulation.
The approximately 2-nm thick surface layers were Znrich, and the inner layers Ga-rich, in the 40-nm thickﬁlm. Low-voltage electron beam excitement luminescence was studied as a function of ﬁlm thickness andelectron acceleration voltage. It was shown that enhancement of the cathodeluminescence took place near
the surface of the bilayer structure of ultrathin andcontinuous surface layers formed by self-assembly.
Acknowledgements
This work was partly supported by a grant from the
FUTABA Electronics Memorial Foundation. The authors wish to thank the Advanced Materials ResearchCenter in the College of Science and Technology at
Nihon University for help with the physical analyses.
References

Fig. 3. Intensity of cathodeluminescence of Zn᎐Ga᎐O sputteredﬁlms, as a function of the anode voltage Va , for electron excitement.

w1x T. Kishino, S. Itoh, Technical Digest, IVMC ’95, 30 July᎐3
August 1995, Portland, OR, Ž1995. 1.
w2x I.J. Hsieh, M.S. Feng, K.T. Kudo, P. Lin, J. Electrochem. Soc.
141 Ž1994. 1617.
w3x S. Itoh, T. Watanabe, K. Ohtsu, M. Yokoyama, M. Taniguchi,
Jpn. J. Appl. Phys. 32 Ž1993. 3955.
w4x H. Isogai, Y. Yoshida, H. Yamamoto, Trans. Mater. Res. Soc.
Jpn. 24 Ž1. Ž1999. 71.

Journal of Physics and Chemistry of Solids 61 (2000) 1047–1050
www.elsevier.nl/locate/jpcs

Observation of condensed structure of C60 assembled
from solution
S. Ogawa*, H. Furusawa, T. Watanabe, H. Yamamoto
College of Science and Technology, Nihon University, 7-24-1 Narashinodai, Funabashi-shi, Chiba 274-8501, Japan

Abstract
Microscopic needle-like structures with submicron sizes were observed in the films prepared by electrolysis. Macroscopic
needle-like structures with few millimeters length were also assembled by an extraction from nonelectrolysis
supersaturated toluene solution. The anisotropic activation energy for two kinds of growing surfaces was investigatedfrom the observation of their characteristic structure. Preparation conditions with thermal-equilibrium were thought to beeffective to obtain a very long and/or fine assembled structure of C60. Conclusively a huge needle-like C60 was obtainedby a very slow extraction. In the sample, ultrafine fibers with a diameter of about 50 nm were observed. 䉷 2000 Elsevier
Science Ltd. All rights reserved.
Keywords: C60; Needle-like structure; Ultrafine fiber

1. Introduction

2. Assembled metal doped C60 by electrolysis

Since the discovery of C60 [1] and the development ofmass production of fullerenes [2], they have been widely
studied in the field of materials science because of theirhigh feasibilities as a new class of functional materials.
Properties of fullerenes often depended on synthesis
processes as shown in the results of single crystals or thinfilms [3]. We have taken notice of a solution process. A few
studies have been carried out with respect to the growthmechanism from the solution phase. The purpose of thiswork is to observe several characteristic structures of C60
assembled from solution and to investigate the growth mode
as a function of growing temperature.
The specimens were prepared by two kinds of solution
processes. One of the processes was electrolysis, and theother an extraction from a supersaturated solution. The
structures of the samples were observed by an electron
microscopy, SEM and/or TEM.

2.1. Sample preparation* Corresponding author. Tel.: ⫹81-47-469-5457; fax: ⫹81-47467-9683.

The electrolysis cell was put in a glovebox filled with N2gas. The cell had two rooms divided by an ion-exchange
membrane. The solution in the working electrode cell was
1.5 mmol/l-C60 toluene. The solution in the counter electrode cell was 0.1 mmol/l-RbClO4 N, N-dimethylformamide(DMF). A black film was deposited on a silver plate of theworking electrode. The temperature of the electrolysis
solution was changed from 10 to 60⬚C. The details ofelectrolysis conditions appeared elsewhere [4].
2.2. Observation of the assembled structure
Fig. 1 shows the typical SEM photographs of RbC60
compounds obtained by changing the temperature of theelectrolysis solution Tele. At comparatively low Teles’,characteristic needle-like particles with the size of a submicron were grown. At Teles’ above 50⬚C the particles
became round.
The growth mode is thought to be reflected in the length
ratio along a long axis and a short axis R for the needle-likestructure. Fig. 2 shows the Allenius plots of the value of R as
a function of Tele. From the results, a difference of an effective activation energy DEact for the two kinds of growing

0022-3697/00/$ - see front matter 䉷 2000 Elsevier Science Ltd. All rights reserved.
PII: S0022-369 7(99)00361-3

1048

S. Ogawa et al. / Journal of Physics and Chemistry of Solids 61 (2000) 1047–1050

3.2. Observation of the assembled structure
The length of the assembled structure at comparatively
low Tsol was typically about few millimeters and thediameter was about 1 mm. The shape of the sample becameround with increasing Tsol as shown in Fig. 3. The Allenius
plots of the value of R as a function of Tsol is shown in Fig. 4.
In this case Tsol means a precipitation speed of C60. Then
DEact was estimated to be about 280 meV, the value of
which was fairly larger than that in the electrolysis samples.
It was confirmed that a very large anisotropic activation
mechanism took place in the thermal-equilibrium forassembled C60 from solution. Conclusively, low-temperature process conditions, namely conditions with thermalequilibrium, were effective to obtain a long and/or fineneedle-like sample.
When the toluene solution was very slowly evaporated ina closed tube, the huge needle-like sample was obtained asshown in Fig. 5. For about 6 months the needle gradually
grew at the inner wall of the tube near the surface of thesolution. The length and the diameter of the sample attained
up to about 20 mm and 100 mm, respectively. The sample
was cut into a very thin piece by a focussed ion beam etching technique, and the cross-section of the sample was also
observed by TEM. Layered structures with a thicknessof about 30 nm were observed. Since a halo electron
diffraction pattern was obtained, the assembled C60 was
amorphous.
As shown in Fig. 6 an ultrafine fiber with a diameter ofabout 50 nm was found as the smallest and fundamental
structure in the huge needle.

4. SummaryFig. 1. The SEM photographs of RbC60 compounds obtained bychanging the temperature of the electrolysis solution Tele.

surfaces in the needle-like structure was estimated to beabout 35 meV.

3. C60 extracted from the nonelectrolysis solution

Assembled structures of C60 were obtained by two
types of solution processes. As a common mode, agrowth of needle-like structures appeared, though thesize was quite different, from micrometers to few tensof millimeters. The anisotropic activation energy for thetwo kinds of growing surfaces was investigated fromthe results of the observation of the samples. As anexperimental proof, a very slow growth of C60 resulted
in a huge needle which was composed of ultrafine
fibers.

Acknowledgements

3.1. Sample preparation
Assembled structures of C60 were extracted from thetoluene solution of C60. The solution of 50 ml was driedin a day and the solution temperature Tsol was changed from
20–40⬚C. Microstructures of the samples were observed by
SEM and TEM.

This work was partly supported by the Grant-in-Aid
for Scientific Research from the Ministry of Education.
The authors would like to thank the Advanced Materials
Research Center of the College of Science and Technology of Nihon University for usages of physicalanalyses.

S. Ogawa et al. / Journal of Physics and Chemistry of Solids 61 (2000) 1047–1050

1049

Fig. 2. The logarithms of the length ratio R observed in the needle-like particles prepared by the electrolysis process vs. 1000/Tele.

Fig. 3. The SEM photographs of C60 extracted from the supersaturated toluene solution by changing the solution temperature.

1050

S. Ogawa et al. / Journal of Physics and Chemistry of Solids 61 (2000) 1047–1050

Fig. 4. The logarithms of R of the samples prepared by the nonelectrolysis process vs. 1000/Tsol.

Fig. 5. The huge needle-like sample that was obtained as a result ofvery slow evaporation of the toluene solution.

Fig. 6. The SEM photograph of an ultrafine fiber in the huge needlelike sample.

References[1] H.W. Kroto, J.R. Heath, S.C. O’Brien, R.F. Curland, R.E.
Smalley, Nature 318 (1985) 162–163.
[2] W. Kratschmer, L.D. Lamb, K. Fostiropoulos, D.R. Huffman,
Nature 347 (1990) 354–358.

[3] D. Schmicker, S. Schmidt, J.G. Skoffronick, J.P. Toennies, R.
Vollmer, Phys. Rev. B 44 (1991) 10 995–10 997.
[4] H. Endo, H. Yamamoto, Trans. IEE Japan 118 (1998) 352–357.

Jpn. J. Appl. Phys. Vol. 41 (2002) pp. 1235–1240
Part 1, No. 3A, March 2002
#2002 The Japan Society of Applied Physics

Growth and Characterization of Anodic Oxidized Films in Pure Water
Kazunori O HNISHI* , Akira I TO{ , Yoshihiro TAKAHASHI and Syunsuke M IYAZAKI
Department of Electronic Engineering, Nihon University, 7-24-1, Narashinodai, Funabashi, Chiba 274-8501, Japan(Received March 14, 2001; accepted for publication December 12, 2001)

An anodic oxidized ﬁlm has been deposited in pure water at room temperature. Film thickness increases linearly as a functionof total charge during oxidation. High ﬁlm deposition rate and low surface roughness are obtained by alternately changing thepolarity of the applied voltage. The ﬁlm growth mechanism is discussed and the model of anodic oxidation in pure water is
proposed. The HF etching rate and the oxide thickness are reduced by an increase in annealing temperature. Though theelectrical characteristics of the anodic oxide ﬁlm are inferior to those of the ﬁlm obtained by thermal oxidation, they can be
improved by thermal annealing at a temperature of 400 C. [DOI: 10.1143/JJAP.41.1235]
KEYWORDS: silicon dioxide, anodic oxidation, low-temperature process, thermal annealing

1.

Introduction

With the progressive shrinking of LSI device size, device
and circuit is complexity increasing. The fabrication process
is also becoming increasingly diﬃcult. Moreover, there is agreat demand to reduce energy consumption on the grounds
of preventing global warming and environmental pollution.
An oxidation process in VLSI fabrication requires a hightemperature of around 1000 C and thermal stress damages
the silicon wafer inconspicuously. From this viewpoint, lowtemperature processes have been researched. Many lowtemperature processes have been proposed to fabricate
insulation ﬁlms on silicon such as plasma deposition,
chemical vapor deposition (CVD), photo-CVD,1) jet vapor
deposition (JVD),2) anodic oxidation and so on.
We considered the possibility of applying the electricaleﬀect to the fabrication process of semiconductor devices at
low temperatures. The ﬁrst thing we noted was theoccurrence of electrically enhanced oxidation and anodic
oxidation on the Si substrate. The eﬀect of the electric ﬁeld
on oxidation has been studied previously.3) Anodic oxidation
has been experimentally studied previously as an oxide
formation process. Usually, anodic oxidation was carried out
with electrolytes such as N methylacetamide (NMA)–KNO3
or tetrahydrofurfutyl alcohol (THF)–KNO3 .4–6) An anodic
oxidized silicon ﬁlm in pure water was also reported byDubrovskii et al.7)
Early works on anodic oxidation reported that the etchingrate was greater than that of thermal oxides and was changed
by impurity solutions and the growth rate was a function of
applied voltage in constant current mode.5,6) There is acontroversy regarding the oxidation mechanism. Dubrovskii
et al. proposed the silicon diﬀusion model in which siliconions diﬀused to the oxide–electrode boundary and formed
the oxide,7) whereas Kraitchman and Oroshnik argued thatthe oxygen migrates close to the oxide–silicon interface andoxide growth occurs at the interface.5)
Although the electrical property is improved by hightemperature annealing in He, the oxide ﬁlms were
substantially porous and the electrical property was poor.
For these reasons, the use of anodic oxidation wasabandoned in integrated circuit fabrication processes.
We intend to study the application of the electrical eﬀect

in the fabrication of integrated circuits at low temperatures.
This will contribute to suppressing the energy consumption
in VLSI fabrication systems. Here, we report on theexperimental method and the characteristics of anodic
oxidized silicon dioxide ﬁlms grown in pure water at room
temperature as a possible oxidation process at a lowtemperature. We discuss the electric characteristics andgrowth mechanism. We clarify that the surface roughness ofthe oxide is improved by alternately changing the polarity of
the applied voltage and that the oxide thickness is notincreased by the applied voltage, but increases with the total
charge ﬂowing between electrodes during oxidation. The
electrical characteristic is improved by annealing over400 C after oxidation.
2.

Experimental

Samples used in our experiments were fabricated asshown in Fig. 1. Wafers used in this experiments were ntype and p-type silicon wafers of h100i plane and theircorresponding resistivities were 3–5 cm and 0.8–
1.2 cm. The wafers were cleaned by ths standard RCA
cleaning method. Anodic oxidation was carried out in purewater with resistivity of 16 Mcm at 20 C. After oxidation,
wafers were annealed in nitrogen atmosphere at various
appropriate temperatures. A reference sample was preparedby thermal oxidation at 1045 C in dry oxygen and annealed
at the same temperature in nitrogen. Film thickness was*

E-mail: ohnishi@ecs.cst.nihon-u.ac.jp
Present address: Sanken Electric Co., Ltd., 3-6-3 Kitano, Niiza, Saitama
352-0003, Japan.

RCA cleaning of silicon substrate ( 1.1 cm x 1.1 cm)
Anodic oxidation
Thickness measurement
by ellipsometer

Thermal oxidation(1045 C, O 2: 500 cc/min)

Thermal annealing (30 min, N2: 500 cc/min)Thickness measurement by ellipsometer
Removal of oxide on Si backside by HF
Fabrication of Al gate MOS diode(Diameter of gate electrode: 0.3mm )

{

1235

Fig. 1. Sample preparation process ﬂow.

1236

Jpn. J. Appl. Phys. Vol. 41 (2002) Pt. 1, No. 3A

K. OHNISHI et al.

3 cm

Output ofController

Pure water(16 M cm)

Output ofVoltage
SourceAmmeter

Pt or Si

(Keithley 2000 Multi-meter)

Teflon water bath

PC

Si

0 [V]

400 ms(Data store)+

Voltage controller

DC voltage source

Fig. 3. Time chart of alternately changed polarity of voltage (AC).

(Alternative voltage generator)

Fig. 2. Anodic oxidation experimental system.

measured by the ellipsometry method. The ﬁlm composition
was analyzed by X-ray photoelectron spectroscopy. Electrical properties were measured using MOS structures withaluminum electrodes. Anodic oxidation was carried out inpure water with the application of a constant voltage acrossthe silicon wafer anode and the other electrode of platinum
or silicon, as shown in Fig. 2. The distance between theelectrodes was 3 cm, and anodic oxidation was carried out
with a constant DC voltage or by alternately changing thepolarity of the voltage (AC). We used the period of 60 s andthe duty ratio of 0.5 for the AC voltage source. Figure 3 is atime chart of applied voltage when the polarity changes
alternately. The current ﬂow during anodic oxidation wasmonitored and integrated to calculate the total charge duringoxidation. Silicon substrates were cut to a 1.1 cm square size,
and the anodic oxidation window was 1 cm square.
3.

600

(a)

400
300

8

200

6

100
0

500
Thickness [ ]

500

300

6

4

2

0

0

y [mm]

0

600

500

500

(c)

400
300
8

200

6
4
8

4
x [mm]

2

0

0

8

2
6

4

y [mm]

20y [mm]

0

(d)

400
300

8

200

6

100
0

2
6

6
4

x [mm]

600

100

8

200

2

8

x [mm]

0

(b)

400

100

4

Thickness [ ]Thickness [ ]Experimental Results

We measured distributions of the thickness of both
samples fabricated with DC and AC voltages. Figure 4
shows proﬁles of oxide ﬁlms in this experiment. Figures 4(a)600

Thickness [ ]400 msPolarity ofElectrode

4
8

2
6

4
x [mm]

200y [mm]

Fig. 4. Proﬁle of oxide thickness. (a) on n-Si with 300 V DC (b) on p-Si with 300 V DC (c) on n-Si with 300 V AC (d) on p-Si with
300 V AC.

Oxide Thickness [ ]800
AC 200400
500
DC 200
500

600

400
200

K. OHNISHI et al.

Etched Oxide thickness [ ]Jpn. J. Appl. Phys. Vol. 41 (2002) Pt. 1, No. 3A

1237

400
Anodic Oxidation Time [min]

300

25
20
15

200

5
100

10

Thermal Oxide

0

0

0

0.1
0.2
0.3
0.4
0.5
0.6
Total Charges during Oxidation [C]Fig. 5. Film thickness vs total charges during anodic oxidation on p-type(100) 3–5 cm Si at 20 C.

and 4(b) show thickness distributions of the oxide ﬁlm on
the n-type and p-type silicon substrates when the voltage
was 300 V DC. Figures 4(c) and 4(d) show distributions of
the oxide thickness when the applied voltage changed
polarity as shown in Fig. 3. The oxide on the n-type
substrate was thinner than that on the p-type substrate andrandomly distributed, but it was improved upon oxidation
with an applied AC voltage as shown in Fig. 4(c). Figure 5
shows the oxide thickness on the p-type silicon substrate
against the total charge ﬂowing in the system duringoxidation for diﬀerent applied voltages. This ﬁgure showsthat the oxide ﬁlm thickness linearly increased with total
charges during oxidation and the oxide obtained with AC
voltage is thicker than that obtained with DC voltage. The
oxide thickness as a function of total charges ﬂowing duringoxidation with AC voltage is twice that with DC voltage.
The composition of the anodic oxidized ﬁlm in our
experiment was analyzed by X-ray photoelectron spectroscopy; it was stoichiometric SiO2 , the same as the thermaloxide formed at 1045 C.
We estimated the etching rate of thermal oxide and anodic
oxide ﬁlms in order to compare the quality. The thermaloxide ﬁlm of 30 nm thickness was grown on a p-type silicon
substrate at a temperature of 1045 C and then it was
reoxidized by anodic oxidation with 300 V AC for 5–25 min.
These samples were etched by a solution of HFð48%Þ :H2 O ¼ 1 : 50 at room temperature. Figure 6 shows theetched oxide thickness against etching time for various
anodic oxidation times. The region of high-etching rate at an
early stage is predominantly of anodic oxide and the regionof low-etching rate a later stage is predominantly thermaloxide being slightly aﬀected by anodic oxidation. This result
reveals that the density of anodic oxide is lower than that ofthermal oxide as reported previously. The etching rate of the and 8–9 A/s for the reoxidized
thermal oxide ﬁlm is 1 A/s,ﬁlm by anodic oxidation. It is conﬁrmed that the etching rateof the oxide ﬁlm fabricated by anodic oxidation (300 V AC)on the silicon substrate is 25 A/s,and the rate of the ﬁlm
grown with DC voltage is higher than that with AC voltage.
The refractive index of the anodic oxide ﬁlm was around however it ranged from 1.3
1.45 for ﬁlms thicker than 200 A,
 The dielectric constants
to 1.4 for ﬁlms thinner than 100 A.

10

20

30

40

50

60

Etching Time [s]Fig. 6. Etched oxide thickness vs etching time for diﬀerent anodic
oxidation times.

1.0

C / Cmax.

0

Applied Voltage
during Oxidation

0.8
200 [V] (AC)500 [V] (AC)0.6
0.4
400 [V] (AC)0.2

300 [V] (AC)

0.0
-7

-6

-5

-4

-3
-2
-1
Gate Voltage [V]0Fig. 7. C–V curves of MOS structures with anodic oxide fabricated at
diﬀerent voltages.

were determined using the thickness measured by ellipsometry and the capacitance measured under accumulation
condition. The estimated dielectric constant was between 4
and 7 and it was higher than that of the thermal oxide.
The electrical characteristics are analyzed from highfrequency C–V and I–V characteristics. Figure 7 shows theC–V curves for diﬀerent anodic voltages and Fig. 8 shows
the density of Si/SiO2 interface states evaluated by theTerman method. Densities of ﬁxed positive charge in theoxide are evaluated by ﬂat-band voltages, and4:5{4:7  1012 cm2 and 3:2  1012 cm2 are obtained when
the applied voltages during oxidation are 200–400 V and
500 V (AC), respectively.
Anodic oxidized ﬁlms were annealed in nitrogen atmosphere at various temperatures. The etching rate and also
thickness decrease as the temperature increases as shown in
Figs. 9 and 10.
Electrical characteristics are improved by high-temperature annealing. Figure 11 shows the C–V curve of a MOS
structure annealed in nitrogen atmosphere at 400 C for
30 min. The anodic oxidized ﬁlm is fabricated with 300 V
AC and the total charge during oxidation is 0.1 C. The
density of ﬁxed positive charge is 4:3  1011 cm2 . Figure
12 shows the density of Si–SiO2 interface states of the same

1238

Jpn. J. Appl. Phys. Vol. 41 (2002) Pt. 1, No. 3A

K. OHNISHI et al.

1.0
Applied Voltage
during Oxidation

1013

Capacitance [pF]

Dit [cm-2 eV-1]

1014

200 [V] (AC)1012

400 [V] (AC)300 [V] (AC)

1011
-0.2

0.2

0

0.6
0.4
0.2

500 [V] (AC)

0.4

0.8

0.0
0.6

-5

0.8

-4

-3

-2

0

2

1

Gate Voltage [V]Surface Potential [eV]Fig. 8. Interface states density vs surface potential evaluated from C–V
curves in Fig. 7.

-1

Fig. 11. C–V characteristic of a MOS structure after annealing at 400 C
for 30 min. Anodic oxide is fabricated at 300 V AC, total charge is 0.1 C.

1013

Dit [cm-2 eV-1]

Etching Rate [ /s]

30
25
20
15

1012

1011

10
1010
-0.2

5

0.2

0.4

0.6

Surface Potential [eV]

0
0

200

400

600

800

1200

1000

Annealing Temperature [Fig. 12. Interface states density vs surface potential evaluated from C–V
characteristic of Fig. 11.

]

Fig. 9. Etching rate of anodic oxide after annealing in N2 atmosphere for
30 min at diﬀerent temperature. Anodic oxidized with DC voltage andtotal charge is 1 C.

Oxide Thickness (Normalized
by that before annealing)

0

100

95

90

85
0

200

400
600
800
Annealing Temperature [1000]

Fig. 10. Thickness change at diﬀerent annealing temperature in nitrogen
atmosphere for 30 min. Anodic oxidation condition is the same as inFig. 9.

structure.
4.

Discussions

In this paper, we explain our experimental results ofanodic oxidation on the silicon substrate in pure water atroom temperature. The growth rate of the oxide ﬁlm on the
n-type substrate is smaller than that of the oxide ﬁlm on thep-type substrate and SiO2 grows only under the condition
that the voltage of the silicon wafer is positive. The
thickness of the oxide ﬁlm increases as the total chargeduring oxidation progresses; this result diﬀers from that of
Dubrovskii’s experiment. Oxidation by alternately changing
the voltage polarity makes the surface roughness decrease.
The oxidation rate on the p-type substrate is larger than thaton the n-type substrate and moreover, the surface ﬂatness of
the anodic oxide ﬁlm on the n-type substrate is poorer thanthat on the p-type substrate. When the electrode polarity
changes alternately, the oxide growth rate is twice that of thecase of single polarity and the surface roughness of the oxide
ﬁlm on the n-type substrate is improved.
From these experimental results, we will consider theanodic oxidation mechanism as follows. A water molecule
has a small dipole moment. Electrons of hydrogen atoms
take positions close to the oxygen atom side. A hydrogenJpn. J. Appl. Phys. Vol. 41 (2002) Pt. 1, No. 3A
Water
H
H

OH
H

O

O
H

K. OHNISHI et al.

Water

SiliconSilicon
Si

H

H

Si

H
Si

O

H
O
H

H

H

H
Si

O

Si
e

H

O
O

Si
Si
Si

H

Si

OH

Si
O

O

OH

Si

Si

Si

Si

Si

Si
Si

Va

Si

Si

H

Si

Si

Si

O

H
O

Si
Si

H

Si

H

Si

O

Si

1239

Si

Si

e

Si

Si

e

Fig. 13. Proposed model of anodic oxidation in pure water.

Water Hatom is slightly positively charged, þ, and the oxygen of awater molecule is slightly negatively charged, 2 as shownin Fig. 13. When the silicon wafer is biased positive against
a cathode, positive charges exist at the water–Si interface.
Oxygen of a water molecule is directed toward the positively
charged Si–water interface as shown in Fig. 13.8) The watermolecule drifts and/or diﬀuses into the silicon bulk, andhydrogen is dissociated from H2 O. This hydrogen is highly
activated and reacts with Si=Si bonds and/or dangling bonds
forming SiH and also breaks the covalent bond of Si=Si.
The oxygen-hydrogen pair atom combines with Si and forms
SiOH.
When a negative bias is applied to the silicon substrate,
the hydrogen of a water molecule is directed toward the Siwater interface and the water molecule is dissociated tohydrogen and hydroxyl by reacting with electrons from thenegative electrode.5) Hydrogen drifts and/or diﬀuses into thesilicon bulk and reacts with Si=Si forming Si–H. OH drifts
out to the water. Another possible mechanism is that OH and
H in the water are dissociated from a water molecule and H
drifts and/or diﬀuses into the silicon bulk and forms Si–H
and/or is positioned at an interstitial site. The hydrogendiﬀuses deeply into the inner space of the silicon bulk due toa large diﬀusion constant.
When the polarity of the supplied voltage to the silicon
substrate is changed from negative to positive, electrons
move from the Si–metal interface to the water–Siliconinterface and the distributed ions at the interface areneutralized by the electrons. Moreover, activated hydrogenremaining in the oxide approaches the water–Si interface.
The hydrogen distributed in the silicon bulk breaks the
Si=Si bond and forms Si–H, and OH from the water–Siinterface forms the Si–O and SiO2 as shown in Fig. 14. Thus
the oxidation rate against total charges during oxidation incase of AC voltage is roughly twice that with DC voltage asshown in Fig. 5. In the case of the p-substrate, holes
accumulate sharply at the interface as shown in Fig. 15.
Meanwhile, in the case of the n-substrate, donor ions form adepletion layer, holes (minority carrier) are present at theinterface as shown in Fig. 16 and a depletion layer restricts
the growth rate.
The growth rate diﬀerence between SiO2 on the n-type
substrate and on the p-type substrate is considered asfollows. In case of the p-type silicon substrate, positive

H
H H
O

H
H H

OH

H
H
H

Water H
H+
H
H
H

O

H

H
H
H
H
H

Silicon
Si

H H
Si

Si
Si

Si
Si

Si

H
Si

Si

H
Si
H

Si
Si

Si

e

Si

Silicon

OH

H

Si

Si
Si
Si

O
O

Si
Si

Si

O

O
OH

Va

Si
Si

H
Si

Si
Si

Va

Si

e

Fig. 14. Anodic oxidation model when the applied voltage changes fromnegative to positive.

charges near the water–Si interface are holes and are sharply
distributed at the silicon surface. Therefore, OH and H react
easily with silicon covalent bonds and dangling bonds, andform SiOH and SiH, respectively. In the case of an n-typesilicon substrate, positive charges near the water–Si interface
are ionized donors and holes that are minority carriers in an
n-type substrate. There is a small number of holes comparedwith the case of the p-type substrate. Thus, the number of H
and OH reacting with holes is smaller than for the p-type
substrate.
5.

Conclusions
We experimented with anodic oxidation in pure water at

1240

K. OHNISHI et al.

Jpn. J. Appl. Phys. Vol. 41 (2002) Pt. 1, No. 3A
H
Water

p-Si

+ Va

O
H
H
HO
OH
H
O

H

E

Si

Energy-band
diagram

Si
Si

Si

accumulation condition

Si

Q
hole
(accumulation)

Si

O
Si

Si

Si

Si

Si

Si

Si

H

Si

Si

Si

H
O

Si

B

Si

H

H

Si

B

water

H

Si

Si

Si

Chargedistribution

H
OH

Si

Si
B

Si

Si

Si

Si

Si
p-Si

Fig. 15. Energy band diagram and charge distribution of n-Si surface.

H
Water

n-Si

+ Va
H

E

O
H
H
HO
OH
H
O

Si
Energy-band
diagram

H
OH

Si

Si
Si

H

Si
Si

water

H

H
H
O H
O

Si
P

Si
Si

Si
Si

Si

depletion condition

Si

Q
hole
(inversion)

Chargedistribution

space
charge

Si

Si
P

Si

Si
Si

Si

Si
Si

Si

Si
Si

Si

Si
P

Si

We also examined the possibility of improving theelectrical characteristic of SiO2 ﬁlms by high-temperatureannealing. The etching rate of the oxide ﬁlm became small,and it was eﬀective in decreasing the density of Si/SiO2
interface states and positive charge density in the oxide.
Our intention in performing this study is to apply theanodic oxide for the following purposes.
1. Low-temperature VLSI processes.
2. Bonded and Etched SOI.
3. Oxide ﬁlm for micro-machining.
It is diﬃcult to apply the anodic ﬁlm to the LSI insulatingﬁlm process directly. However, it will be possible toimprove the quality by controlling the resistivity of purewater, substrate temperature and voltage stability. If theanodic oxide can be applied to an oxidized substrate tofabricate a BE–SOI wafer, an inexpensive SOI substrate canbe obtained. We consider that the most realistic application
at this stage is the use of the anodic oxide for micromachining.
We attempted to apply the anodic oxidation to aid the
suppression of global warming and environmental pollution,and made a tiny step toward the application of the electricaleﬀect to the device fabrication process. We hope this study
will contribute to positive changes in the use of energy.
Acknowledgement

Si

Si
n-Si

Fig. 16. Energy band diagram and charge distribution of p-Si surface.

room temperature as a possible low-temperature process andalso discussed the growth mechanism using a model ofmolecular dipoles of water. We found that alternatelychanging the polarity of the applied voltage operates
eﬀectively to cause anodic oxidation. We also found thatthe composition of the oxide was stoichiometric SiO2 , theoxide thickness increased with charges ﬂowing duringoxidation and the growth rate on p-type silicon was higher
than on n-type silicon. The surface roughness was larger on
n-type silicon than on p-type silicon. When the applied
voltage polarity was changed alternately, surface roughness
became small and the growth rate became twice that in thecase of single polarity.

We would like to thank Professor P. M. Lenahan ofPennsylvania State University for useful suggestions. We
also wish to thank M. Saitou for experimental support andhelp with the ﬁgures. This work was supported partly by
Fund of Research Project of College of Science andTechnology, Nihon University.
1) Y. Numasawa, K. Yamasaki and K. Hamano: Jpn. J. Appl. Phys. 22(1983) 792.
2) X. Wang, T. P. Ma, G. Cui, T. Tamagawa, J. W. Goltz, S. Karechi, B.
H. Halpern and J. J. Schmitt: Jpn. J. Appl. Phys. 34 (1995) 955.
3) P. J. Jorgensen: J. Chem. Phys. 37 (1962) 874.
4) E. F. Duﬀek, C. Myroie and E. A. Bejamini: J. Electrochem. Soc. 111(1964) 1042.
5) J. Kraitchiman and J. Oroshnik: J. Electrochm. Soc. 114 (1967) 405.
6) A. G. Revesz: J. Electrochem. Soc. 114 (1967) 629.
7) L. A. Dubrovskii, V. G. Mel’nik and L. L. Odynets: Russ. J. Phys.
Chem. 36 (1962) 1183.
8) J. P. Hogan, A. M. Stoneham and M. Jaros: Philos. Mag. B 55 (1987)
225.

Japanese Journal of Applied Physics
Vol. 44, No. 1B, 2005, pp. 617–620#2005 The Japan Society of Applied Physics

Preparations and Evaluations of C60 Thin Films for Organic Field-Eﬀect Transistors
Nobuyuki I WATA, Akane KINJO, Hiroki O KUYAMA and Hiroshi Y AMAMOTO
Department of Electronics and Computer Science, College of Science and Technology, Nihon University,
7-24-1 Narashinodai Funabashi-shi, Chiba 274-8501, Japan(Received June 25, 2004; accepted August 23, 2004; published January 24, 2005)

Fullerene C60 thin ﬁlms were grown on a mica top-gate-type substrate and on a CaF2 == Si(111) bottom-gate-type substratewith the aim of fabricating high-performance organic ﬁeld-eﬀect transistors (FETs). It is expected that single-crystal C60 thinﬁlms with a large grain have a high mobility as n-type materials because of the lack of a potential barrier at the grainboundaries for conducting electrons. On both substrates, oriented C60 ﬁlms were obtained. In particular, on the mica substrate,
the highly oriented ﬁlms had grains larger than 1  1 mm and a two-dimensionally ﬂat surface with 60 and 120 deg facets. The
step height was 0.8 nm, consistent with that of an hcp bulk structure. The highly oriented ﬁlms were grown at the substratetemperature at which the C60 molecules at the tips of spiral grains re-evaporated. The obtained single-crystal C60 thin ﬁlms
with large grains are promising for high-performance organic FETs. [DOI: 10.1143/JJAP.44.617]
KEYWORDS: C60 , organic, mica, calcium ﬂuoride (CaF2 ), Si(111), thin ﬁlm, FET, epitaxial growth, molecular beam epitaxy(MBE), atomic force microscopy (AFM)

1.

ﬂux rate using a thickness monitor, while for CaF2 , it was
kept constant at 1150 C, the ﬂux of which was 1:9  104
Torr derived from the temperature dependence of steampressure.
Cleaved natural mica substrates were set on the sample
holder, where copper foils with 0.01 mm thickness wereinserted between the holder and substrate for a better thermal
contact and temperature uniformity. Prior to deposition thesubstrate was prebaked at 400 C for 60 min in vacuum. A
growth rate of 3.0 nm/min was obtained for a ﬁlm deposited
on a glass substrate at room temperature. The pressureduring C60 ﬁlm deposition was approximately 2:0  108Torr.
The p-type Si (111) substrate for CaF2 growth, theresistivity of which was less than 0.02 cm, was cleaned
ultrasonically for 60 s in Semicoclean23 solution (Furuuchi
Chem. Co.) to remove organic impurities, etched by acidsolution (HF:HCl:H2 O = 1:4:7) for 60 s and then rinsed
with pure water. Those processes were carried out threetimes. Immediately the substrate settled on the sample
holder with the insertion of 0.01-mm-thick Pt/Au foils andwas loaded in the chamber. CaF2 ﬁlm is deposited at 250 C
for 10 min and at 660 C for 60 min, at which the pressures
were approximately 1  108 Torr and 8  108 Torr, respectively.
Surface morphology is observed by atomic force microscopy (AFM) (Seiko Instruments Inc. SII: SPI3800). The
crystalline structures of the ﬁlms are studied by X-ray
diﬀraction analysis (XRD) (Rigaku: RAD-C).

Introduction

Recently, organic ﬁeld-eﬀect transistor (FET) devices
have become attractive from the viewpoints of low cost,mechanical ﬂexibility, low-temperature processing and soon. The performance of organic FETs should be comparable
to that of amorphous silicon. Among organic semiconductors, pentacene has been well known as a p-type material
because of its high mobility of 1.5 cm2 /Vs, while n-typematerials with high mobility are extremely desired fororganic complementary circuits.1) Fullerene C60 is expected
as an n-type organic material. A practical in-situ measurement has demonstrated a high mobility of 0.5 cm2 /Vs in a
C60 thin ﬁlm.2) In another study, alumina-passivated C60 thinﬁlm with a mobility of 0.1 cm2 /Vs prevents the degradationof FET performance.3) However, there have been no reports
focusing on how the crystallinity of the ﬁlm and grain sizeaﬀect FET performance for n-type organic semiconductors.4)
Therefore we tried to grow C60 single-crystal thin ﬁlms witha large grain in order to achieve a high FET performance. In
such ﬁlms, carrier transport is not suppressed because of few
scatterings of carriers at grain boundaries.
In this study we discuss the single-crystal growth of C60
thin ﬁlms for two types of FET: top-gate type and bottomgate type. Natural mica and CaF2 == Si(111) were used as
top-gate- and bottom-gate-type substrates, respectively.
Calcium ﬂuoride worked as a gate insulator and buﬀer layer
for the growth of single-crystal C60 thin ﬁlms.
2.

Experimental

3.

Films were prepared using an ultra-high-vacuum molecular beam epitaxy (UHV-MBE) system with a backgroundpressure of less than 1  108 Torr. The chamber for ﬁlm
growth and the prechamber for sample exchange were
evacuated using a 2000 L/s diﬀusion pump and a 220 L/sturbomolecular pump, respectively. The substrate temperature, TS , was measured using an optical pyrometer throughthe viewport of a ZnSe window. The powders of C60 with
99.9% purity and of CaF2 with 99.99% purity were
evaporated from a pyrolytic boron nitride (PBN) cruciblein eﬀusion cells. Cell temperature for C60 deposition wasincreased during growth in order to maintain a constant C60

Results and Discussion

3.1 C60 ﬁlms growth on mica substrate5)
Figure 1 shows a typical 2- XRD pattern of the C60 thinﬁlm grown at 186 C on the mica substrate. From theconsideration of each peak intensity, the XRD pattern of the
ﬁlm was assigned as that of an hcp structure rather than an
fcc one. Other reﬂection peaks were found to originate fromthe substrate. The lattice spacing of C60 (0002), ﬁtted by a
Nelson-Riley function, was 0:817  0:001 nm, similar tothat of hcp C60 bulk, which is 0.818 nm.
Figure 2 shows the TS dependence of the full width at half
maximum (FWHM) of the (0002) Bragg reﬂection. The
617

Jpn. J. Appl. Phys., Vol. 44, No. 1B (2005)

N. IWATA et al.

a) 40 °Cb) 80 °C

C60(0006)

103

C60 (0004)

C60(0002)

Intensity (arb. units)

618

102

101
5

10

15

20

25

30

35

40

45

50

2θ (deg)
Fig. 1. XRD pattern of C60 ﬁlm grown on mica substrate at 186 C. Boldpeaks were indexed to C60 (0002), C60 (0004) and C60 (0006),
respectively. The other peaks are attributed to the substrate.

0 nmc) 100 °C

7.58 nm

0 nm

11.17 nmd) 120 °C

0.20

FWHM (deg)

0.18
0.16
0 nm

0.14

15.65 nm 0 nm

14.96 nmFig. 3. AFM images of C60 ﬁlms grown on mica substrate at substratetemperature range from 40 to 120 C.

0.12
0.10
0.00
0

20 40 60 80 100 120 140 160 180 200
Substrate Temperature (°C)

Fig. 2. Substrate temperature dependence of full width at half maximum(FWHM) of C60 (0002) Bragg reﬂection of ﬁlm.

FWHM decreased up to 80 C and was constant at the TS
range from 80 C to 180 C. Above 180 C the FWHM rapidly
increased. In general, the FWHM of the 2- Bragg peakdepends on the ﬂuctuation of lattice spacing and ﬁlm
thickness. In this case the FWHM should decrease withdecreasing ﬂuctuation and increasing temperature. The
FWHM should increase with increasing temperature since
ﬁlm thickness decreased due to the re-evaporation of C60
molecules. These two factors resulted in the observed
relationship of FWHM vs TS .
Figure 3 shows the AFM images of a 2 mm2 area of the
C60 thin ﬁlms grown at the temperature range from 40 to120 C on mica substrates. The grains grown at 40 C with agrain size of 50 nm were spread across the surface, as shownin Fig. 3(a). As substrate temperature increased the grain
size also increased. Some of the grains grown at 80 C with agrain size of 150 nm formed triangular structures, as shownin Fig. 3(b). For the grains grown at 100 C, the triangularstructures can be clearly seen as shown in Fig. 3(c). Eachgrain was separated distinctly by grain boundaries. At 120 C
the triangular grains began to coalesce, as shown in
Fig. 3(d).
AFM images obtained at higher temperatures are shown in
Fig. 4. The images on the left-hand side are of an area 2 mm2and those on the right-hand side are of an area 5 mm2 . The

coalesced grains had a spiral structure and were approximately 1  1 mm2 as shown in Figs. 4(a-1) and 4(a-2). Stepsand terraces can be clearly observed. With increasing
substrate temperature, terrace width increases. Separated
grains are evident in Figs. 4(a-1) and 4(a-2) indicating the 3dimensional (3D) growth mode. At 185 C, Figs. 4(b-1) and4(b-2), the separated grains were not obvious, and spiralgrowth was obtained in some places on the 2-dimensionallyﬂat surfaces of the C60 thin ﬁlm, indicating 3D growth on the
2-dimensional (2D) surface. The terraces of the spiral grains
sometimes had a discrete stack of terraces and/or screw
dislocations, which could be from the incommensuratelattice match between the step height of the mica substrate
and the radius of C60 .6) At 197 C, Figs. 4(c-1) and 4(c-2),
there was no spiral growth. Steps and terraces appeared with
60 and 120 deg facets, indicative of the 2D growth mode.
The ﬁlm thickness was less than 10 nm. Epitaxial growthwith a single hcp structure took place in these ﬁlms. Above
this temperature, no ﬁlm and no AFM images were obtained
due to the re-evaporation of C60 .
The change in the growth mode probably occurred withincreasing substrate temperature. However, at above 185 C,
at which signiﬁcant re-evaporation occurred, C60 molecules
at the tip of the spirals should re-evaporate ﬁrst. Eventually,
the diﬀerence in the type of surface was caused not by thediﬀerence in growth mode but by the re-evaporation of C60 .
Figure 5 shows the AFM image at another point of the
ﬁlm shown in Figs. 4(c-1) and 4(c-2) with a line proﬁle. The
step height of 0.8 nm was consistent with the lattice spacingof (0002) for the C60 hcp bulk structure.
The surface roughness Ra is shown as a function of TS in
Fig. 6. The Ra decreased linearly with increasing TS up toJpn. J. Appl. Phys., Vol. 44, No. 1B (2005)

0 nma-2) 5 μm2

6.59 nmb-1) 185 °C, 2 μm2

0 nm

619

2.0

7.28 nmSurface Roughness Ra ( nm )a-1) 149 °C, 2 μm2

N. IWATA et al.

1.6
1.2
0.8
2μm2
5μm2

0.4
0.0

0

50
100
150
Substrate Temperature (°C)b-2) 5 μm2

200

0 nm

3.07 nmc-1) 197 °C, 2 μm2

0 nm

5.71 nmc-2) 5 μm2

ln(Average radius of grain) (μm)

Fig. 6. Substrate temperature dependence of surface roughness Ra of C60
ﬁlms prepared on mica substrates.

Substrate Temperature (°C)
280 240 200 160 120
80
0
-1

40

0.20 eV

-2
-3
-4
1.8

2.0

2.2

2.4 2.6 2.8 3.0
1 / Ts (10 -3/K)

3.2

3.4

Fig. 7. Arrhenius plot for average radius of grains observed in ﬁlms
deposited on mica substrates.

0 nm

4.86 nm

0 nm

6.19 nm1.06 nmFig. 4. AFM images of C60 ﬁlms at higher substrate temperature range
from 149 to 197 C. Left-hand side shows images of 2 mm2 area and righthand side shows images of 5 mm2 area.

1340 nmFig. 5. AFM image and line proﬁle are shown for ﬁlm grown at 197 C.
The height of the steps was 0.8 nm corresponding to the lattice spacing of
C60 (0002).

150 C, and then rapidly decreased to a minimum. The rapid
decrease was consistent with the diﬀerence in surface
morphology due to marked re-evaporation of C60 molecules
present at the tip of the spiral grain.
Using all the AFM images of the ﬁlms prepared at various
TS ’s, the Arrhenius plots of the average radius of the grains
are drawn in Fig. 7 assuming that all the grains were
spherical. The obtained data were ﬁtted to a straight line forthe wide range of TS , though dispersion was slightly
observed in the region of higher TS . It was concluded thatthe growth mechanism can be explained by the simple modelin which the C60 molecules migrate while thermally overcoming the activation energy of approximately 0.20 eV.
3.2 C60 /CaF2 ﬁlm growth on Si (111) substrate
The surface morphologies of CaF2 and C60 /CaF2 areshown in Fig. 8. Equilateral triangular grains with twodimensionally ﬂat terraces were observed with a side lengthof 100–800 nm and a height of 20–80 nm. The azimuth of theapex of triangular grains was along one direction, indicating
epitaxial growth.
Generally, with increasing substrate temperature, decreasing ﬂux and/or terrace width, the growth mode is transformed from pure terrace nucleation through a mixed step

620

Jpn. J. Appl. Phys., Vol. 44, No. 1B (2005)a) CaF20 nm

N. IWATA et al.

b) C60/CaF2

111 nm0 nm

436 nmFig. 8. AFM images of (a) CaF2 ﬁlm and (b) C60 /CaF2 on Si(111) withsize of 5 mm2 .

and terrace nucleation, to pure step nucleation and step
ﬂow.7) Pure terrace nucleation is observed at approximately
600 C. The surface obtained was similar to that of the pureterrace nucleation at the substrate temperature of 660 C,
which is the highest limit of our system. The ﬂux rate of
CaF2 was rather low compared with that in the literature,7)
therefore smoother surfaces can be obtained on a substratewith narrower terraces.
As shown in Fig. 8(b), the C60 ﬁlm was deposited on the
CaF2 == Si(111) substrate at 190 C for 30 min. The surface
morphology basically shows triangular grains which are
obscure. The XRD proﬁle shows the Bragg reﬂections of the
hcp structure similar to that of the C60 ﬁlm on the mica
substrate.
4.

Conclusion

Single-crystal C60 thin ﬁlms were grown on a mica topgate-type substrate and on a CaF2 == Si(111) bottom-gatetype substrate in order to achieve a high FET performance. It
is expected that carrier transport is not suppressed because of
the few scatterings of carriers at grain boundaries in the ﬁlms

with large grains and then a high FET performance isachieved. On the mica substrate, a highly oriented hcp C60
ﬁlm with a 2D ﬂat surface grew just below the temperature
above which C60 molecules totally re-evaporated. Twodimensionally ﬂat surfaces, which had a step and terrace
structure with 60 and 120 deg facets, were achieved becauseof the re-evaporation of C60 molecules from the tip of the
spiral grains. The height of the steps (0.8 nm) was consistent
with that of hcp bulk. Grains larger than 1  1 mm2 wereobtained. Under the same growth conditions as those for the
mica substrate, an oriented hcp C60 ﬁlm was obtained on theepitaxial CaF2 == Si(111) substrate, the surface of whichshowed equilateral triangular grains with a two-dimensionally ﬂat terrace. The side length of the grains was 100–
800 nm and the height of the grains was 20–80 nm. On bothsubstrates, oriented C60 ﬁlms were obtained. In particular theﬁlms on the mica substrate were promising as highperformance organic FETs.
Acknowledgement
The authors are grateful for the ﬁnancial support of theGrant-in-Aid from the Futaba Electronics Memorial Foundation.
1) Y. Lin, D. J. Gundluch, S. Nelson and T. N. Jackson: IEEE Electron
Device Lett. 18 (1997) 606.
2) S. Kobayashi, T. Takenobu and S. Mori: Appl. Phys. Lett. 82 (2003)
4581.
3) K. Horiuchi, K. Nakada, S. Uchino, S. Hashii, A. Hashimoto, N. Aoki,
Y. Ochiai and M. Shimizu: Appl. Phys. Lett. 81 (2002) 1911.
4) C. D. Dimitrakopoulos and P. R. L. Malenfant: Adv. Mater. 14 (2002)
99.
5) N. Iwata, K. Mukaimoto, H. Imai and H. Yamamoto: Surf. Coat. Tech.
169–170 (2003) 646.
6) J. Fujita, S. Kuroshima, T. Satoh, J. S. Tsai, T. W. Ebbesen and
K. Tanigaki: Appl. Phys. Lett. 63 (1993) 1008.
7) M. A. Olmstead: Heteroepitaxy of Disparate Materials: From Chemisorption to Epitaxy in CaF2 /Si(111), eds. W. K. Liu and M. B. Santos(World Scientiﬁc Publishing Co., Pte., Ltd., Singapore, 1999), Chap. 5,
p. 211.

Japanese Journal of Applied Physics
Vol. 44, No. 1B, 2005, pp. 736–738#2005 The Japan Society of Applied Physics

Preparation of Nano-Structured C60 Thin Films
Akane K INJO, Hiroki O KUYAMA, Nobuyuki I WATA and Hiroshi Y AMAMOTO
College of Science and Technology, Nihon University, 7-24-1 Narashinodai, Funabashi-shi, Chiba 274-8501, Japan(Received June 25, 2004; accepted October 26, 2004; published January 24, 2005)

Sapphire (0001) substrates were annealed at 1000 C for 12 h in air to obtain ﬂat surfaces with a step-terrace structure. Au ﬁlms
were deposited on the substrates using the molecular beam epitaxy (MBE) method, at various substrate temperatures. The
surface morphology of the ﬁlms was observed by means of atomic force microscopy (AFM). A quasi one-dimensionalalignment of Au particles was partially prepared along the steps at the substrate temperature of 620 C. On the other hand, an
atomically ﬂat Au thin ﬁlm was obtained at the low substrate temperature of 130 C. A C60 monolayer was obtained by reevaporating the C60 molecules deposited on the Au ﬁlms, which was conﬁrmed by X-ray photoelectron spectroscopy(XPS). [DOI: 10.1143/JJAP.44.736]
KEYWORDS: C60 monolayer, nanostructure, step, terrace, diffusion barrier, atomic force microscopy (AFM)

1.

Introduction

Recently, the fabrication of electronic devices has reachedthe nanoscale level with the continued increase in the densityof integration. Therefore, the fabrication processes ofdevices are becoming increasingly complicated and costly.
The aim of this study is to fabricate a nanoscale structurewith functional molecules, in particular, a monolayer of C60
molecules was aligned one- and/or two-dimensionally by are-evaporation method. In this method, an important aspectis that the binding between C60 and metals is stronger thanthat among the C60 molecules. After the growth of C60 /Au
and annealing, only those C60 molecules directly adsorbed
onto metals remained, whereas the molecules bound with aweak Van der Waals interaction were re-evaporated.
Then the alignment of metals is a particularly important
process for obtaining nano-structured C60 ﬁlms. We havetaken note of the surface structure of oxide single crystal
substrates. A simple process has been reported for obtaining
atomically ﬂat surfaces with a step-terrace structure.1,2) On
such substrates, Au ﬁlms were deposited by molecular beam
epitaxy (MBE) while changing the substrate temperature.
The surface morphology of the obtained ﬁlms was observed
and discussed with respect to the synthesis of nanostructured C60 monolayers.
2.

(a) Annealed substrate(b) Deposition of Au ultrathin film(c) Deposition of C60 thin film

Experimental Procedure

Figure 1 shows the process proposed for the fabrication of
C60 low-dimensional structures, particularly the one-dimensional (1D) structure. (a) The substrates with step-terrace
structures are prepared. (b) 1D Au alignments are formed
along the steps of the substrates. It is expected that the steps
function as a potential barrier for the migration of Au atoms
and Au particles aligned along the steps. Therefore, a highsubstrate temperature and/or a low Au ﬂux rate are adesirable condition. For the two-dimensional (2D) alignmentof Au particles, a low substrate temperature is possibly anappropriate condition. (c) C60 molecules are deposited on thesubstrates. (d) Annealing is carried out in situ to re-evaporate
only those C60 molecules bound with weak Van der Waals
interactions.3)
Films were grown using an MBE system which was
evacuated by a diﬀusion pump and a turbomolecular pump.
The background pressure was approximately 1  108 Torr.
After the Al2 O3 substrates are cleaned ultrasonically in(d) After annealing

Fig. 1. Schematic images of proposed process for the fabrication of C60
low-dimensional structures on Au layers. (a) Step-terrace structure of
single crystal surface, (b) one-dimensional alignment of Au, (c) as-grown
C60 ﬁlm and (d) one-dimensional alignment of C60 .

acetone, they are annealed at 1000 C for 12 h in air. The
annealed substrates are pre-baked at 400 C for 30 min in
vacuum, prior to the deposition. The growth temperatures ofthe substrates are measured using an optical pyrometer. Au
with 99.99% purity and C60 powder with 99.95% purity areevaporated from pyrolytic boron nitride (PBN) crucibles in
Knudsen cells. Table I shows the details of conditions for736

Jpn. J. Appl. Phys., Vol. 44, No. 1B (2005)
Table I.

A. KINJO et al.

Conditions of ﬁlm growth.

K-CellSubstrates
Deposition
temperature ( C) temperature ( C) time (min)Annealing after
deposition

Au

1200–1300

130–630

1.5–40

130–630 C 30 min

C60

350

190

5–10

350 C

30 minﬁlm growth. Au deposition is usually completed after theappearance of additional spots and/or rings of Au in thereﬂection high-energy electron diﬀraction (RHEED) patternof the substrate. During the deposition, the temperature of
the C60 K-Cell is controlled in order to maintain a constant
ﬂux rate using a crystal thickness monitor.
The surfaces of the ﬁlms were observed in situ by RHEED
during deposition and annealing. After the air exposure of
the samples, the surface morphology was measured byatomic force microscopy (AFM) (Seiko Instruments Inc. SII:SPI3800) and the chemical binding condition of C60 was
measured by X-ray photoelectron spectroscopy (XPS)(SHIMADZU Co.: ESCA-850, X-ray: MgK). The XPS
peaks were detected every 6 s during etching by Ar ionsaccelerated at 2 kV. The sample size was approximately
3 mm2 . Vertical diﬀerential charging was calibrated by theAu 4f5=2 peak.
Resistivity was measured by the four-point probe method.
Comb-type Au electrodes were prepared on the substrateprior to the ﬁlm deposition.
3.

737

Results and Discussion

3.1 Surfaces of -Al2 O3 (0001) substrate
Figure 2 shows an AFM image of a sapphire (0001)
substrate annealed at 1000 C for 12 h. The surface shows
uniform parallel steps and atomically ﬂat terraces with
0.21 nm step height and 80 nm terrace width. Uniform
parallel steps are suitable for electrical conduction measurements of the Au particles one-dimensionally aligned along
the steps.
3.2 One-dimensional structure
Figure 3 shows the AFM images of Au particles evaporated on the annealed substrates under the substrate temperature conditions (Ts) of (a) 350 C, (b) 500 C and (c) 620 C.
The Au ﬂux was ﬁxed at 1.64 mTorr, which was derived
from the temperature dependence of the equilibrium vapor
pressure. The Au particles with diameters of approximately
10 nm were distributed without alignment at the Ts of (a)350 C and (b) 500 C. At the Ts of (c) 620 C, particles had

Fig. 2. AFM image (1000 nm2 ) of -Al2 O3 (0001) substrate.

(a)

(b)

(c)

(d)

Fig. 3. AFM images (1000 nm2 ) of Au particles deposited on -Al2 O3(0001) substrate at diﬀerent substrate temperatures of (a) 350 C,(b) 500 C, (c) and (d) 620 C. Au ﬂux rates for (a)–(c) were 1.64 mTorr
and that for (d) was 0.820 mTorr.

diameters of approximately 20 nm and were aligned partiallyalong the lower and/or higher sides of the substrate steps.
Figure 3(d) shows the AFM image of Au particles depositedat the Ts of 620 C under the Au ﬂux of 0.820 mTorr. In thiscase, comparatively small Au particles with diameters ofapproximately 13 nm tended to align around the steps. Fromthe comparison of the results in Figs. 3(c) with those in 3(d),it is conﬁrmed that the diameter of the Au particles became
smaller and the probability of the adherence of the Au
particles at the steps became higher upon decreasing the ﬂux
rate.
By decreasing the ﬂux rate and/or increasing the substratetemperature, the migration length of the deposited atoms
increases. Therefore, the probability of the collision of atoms
on the terraces was decreased, and then the deposited Au
atoms reached the substrate steps and nucleated there. Whenatoms collide with other atoms on a terrace and grow beyond
the critical radius of the nucleus, the collided particles do notreach the steps due to the higher potential barrier for
migration, and thus they could form nucleation sites on theterrace. As shown in Fig. 3(d), the 1D nanostructure of Au
particles appeared partially along the steps under thecondition of Ts ¼ 620 C and ﬂux rate of 0.820 mTorr,
under which condition the atoms can gain the migrationenergy required to reach the steps.
The Au particles become spherical as a general tendency
because of the large diﬀerence in surface energy between Au
and the substrate.4) It is considered that comparatively small
Au particles are more suitable for 1D alignment throughconnecting with eath other along the steps than large
particles are.
3.3 Two-dimensional structure
Figure 4 shows the RHEED patterns of (a) the annealed
surface of sapphire (0001) substrates and (b) the Au thin ﬁlm

Jpn. J. Appl. Phys., Vol. 44, No. 1B (2005)

A. KINJO et al.

Photoemission Intensity (arb.units.)

738

(a)

288

287

286

285

284

283

282

281

280

Binding Energy (eV)Fig. 6. XPS spectra of C1s peak of C60 /Au//Al2 O3 (0001).

(b)
Fig. 4. RHEED patterns of (a) the annealed surface of -Al2 O3 (0001)
and (b) deposited Au on Al2 O3 substrate. Electron beam was incident
from the [11 00] direction.

evaporated under the conditions of Ts ¼ 130 C and the Au
ﬂux rate of 0.82 mTorr. The electron beam was incident
from the [11 00] direction perpendicular to the step lines.
After the deposition of Au, the characteristic pattern on thesubstrate disappeared and faint diﬀraction rings from Au
were observed, indicating the growth of polycrystalline Au
ﬁlms.
Figure 5 shows an AFM image of the Au ﬁlm. The image
is similar to that of the substrate, which indicated an
atomically ﬂat Au thin ﬁlm. This planar structured Au ﬁlm
was applied in the synthesis of a 2D structured C60
monolayer. The specimen was prepared by a process
involving the deposition of C60 ﬁlms on the 2D Au ﬁlm
and successive re-evaporation at 350 C.
Figure 6 shows an XPS spectrum of a C60 thin ﬁlm after
6 s etching. This specimen was prepared on a Au thin ﬁlm by
the re-evaporation method. It is known that a monolayer of
C60 on Au has a metallic property because of the chargetransfer from Au to C60 and the XPS C1s peak with the tailextended to the higher binding energy side.5,6) The observed
asymmetric peak of the C60 ﬁlm was consistent with theFig. 5. AFM images (1000 nm2 ) of deposited Au on Al2 O3 at the substratetemperature of 130 C and ﬂux rate of 0.820 mTorr.

result for the C60 monolayer. Thus, it is apparent that the reevaporation method is useful for the preparation of C60
monolayer on Au ﬁlms.
The resistivity of the Au thin ﬁlm was too high, namely,
above 1 kcm, to be measured using our measurement
system. However, it is expected that the electric conductivityof C60 monolayer can be measured and investigated in C60
ﬁlms deposited on such a highly resistive Au ﬁlm.
4.

Conclusion

The 1D alignment of Au particles could be achieved onannealed -Al2 O3 (0001) substrates by increasing thesubstrate temperature and decreasing the ﬂux rate because
the steps function well as a potential barrier for the migrationof Au atoms. The nanostructured 1D alignment of Au
particles appeared partially along the steps under thecondition of Ts ¼ 620 C and ﬂux rate of 0.820 mTorr.
Atomically ﬂat 2D Au thin ﬁlms were deposited at
Ts ¼ 130 C and the Au ﬂux rate of 0.82 mTorr. After the
C60 deposition on the Au thin ﬁlm//Al2 O3 (0001), the reevaporation of C60 was carried out by annealing at 350 C. It
was conﬁrmed on the basis of XPS analysis that C60
monolayers can be synthesized on Au thin ﬁlms by the reevaporation method.
Acknowledgement
This work was supported by the Ministry of Education,
Culture, Sports, Science and Technology through Scientiﬁc
Grants-In-Aid (No. 12650322 & 15360173). The authors arealso grateful for the ﬁnancial support of a Grant-in-Aid fromthe Futaba Foundation.
1) M. Yoshimoto, T. Maeda, T. Ohnishi and H. Koinuma: Appl. Phys.
Lett. 67 (1995) 2615.
2) Y. Shiratsuchi, M. Yamamoto and Y. Kamada: Jpn. J. Appl. Phys. 41(2002) 5719.
3) E. I. Altman and R. J. Colton: Surf. Sci. 279 (1992) 49.
4) T. Ikoma et al.: Ouyoubuturidetabukku (Data Book of Applied
Physics) (Maruzen, Tokyo, 1994) p. 290 [in Japanese].
5) J. E. Rowe, P. Rudolf, L. H. Tjeng, R. A. Malic, G. Meigs and C. T.
Chen: J. Mod. Phys. B 6 (1992) 3909.
6) M. S. Dresselhaus, G. Dresselhaus and P. C. Eklund: Science ofFullerenes and Carbon Nanotubes (Academic Press, San Diego, 1996)
Chap. 17.