2011A1864

BL14B2X ⥺྾཰ᚤ⣽ᵓ㐀 ᐃ࡟ࡼࡿ Eu ῧຍ GaN ࡟࠾ࡅࡿEu ࢖࢜ࣥࡢ࿘㎶ᒁᡤᵓ㐀㻔V㻕Local Structures around Eu Ions in GaN Studiedby X-ray Absorption Fine Structure 㻔V㻕⸨ཎ ᗣᩥ a, すᕝ ᩔ a, ᮤ ᮾᘓ a, ᕝ⁕ ᪸భ a, ኱ῲ ༤ᐉ b, ᮏ㛫 ᚭ⏕ b
Yasufumi Fujiwaraa, Atsushi Nishikawaa, Dongun Leea, Kosuke Kawabataa,
Hironori Ofuchib, Tetsuo Honmaba኱㜰኱Ꮫ, b 㻔㈈㻕㧗㍤ᗘග⛉Ꮫ◊✲ࢭࣥࢱ࣮a
Osaka University, b JASRI᭷ᶵ㔠ᒓẼ┦࢚ࣆࢱ࢟ࢩࣕࣝἲ࡟ࡼࡾస〇ࡋࡓ Eu ῧຍ GaN ヨᩱࡢ Eu ࢖࢜ࣥ࿘㎶ᒁᡤᵓ㐀ࢆ X⥺྾཰ᚤ⣽ᵓ㐀㻔XAFS㻕 ᐃ࡟ࡼࡾㄪ࡭ࡓࠋヨᩱస〇᮲௳࡜ࡋ࡚ࠊᡂ㛗ᅽຊࢆኚ໬ࡉࡏࡿࡇ࡜࡟ࡼࡿ Eu ࢖࢜ࣥ࿘㎶ᒁᡤᵓ㐀࡜ࡢ┦㛵ࢆ᫂ࡽ࠿࡟ࡋࡓࠋලయⓗ࡟ࡣࠊᡂ㛗ᅽຊࡀῶᑡࡍࡿࡇ࡜࡟ࡼࡾEu ࢖࢜ࣥࡢ➨஧㏆᥋ཎᏊ࡛࠶ࡿ Ga ࡢ఩⨨ᦂࡽࡂࡀ኱ࡁࡃ࡞ࡿࡇ࡜ࡀศ࠿ࡗࡓࠋࡇࢀࡽ࿘㎶ᒁᡤᵓ㐀ࡢኚ໬ࡣࣇ࢛ࢺ࣑ࣝࢿࢭࣥࢫ ᐃ࡟࠾ࡅࡿⓎගࣆ࣮ࢡࡢࣈ࣮ࣟࢻ໬࡜┦㛵ࡀ࠶ࡿࠋࡇࡢ⤖ᯝࡣ V ᪘ཎᩱ࡜ III ᪘ཎᩱࡢ౪⤥ẚ㻔V/III ẚ㻕ࢆ᭱㐺್ࡼࡾቑຍࡉࡏ࡚ᡂ㛗ࡋࡓ Eu ῧຍ GaN ヨᩱࡢഴྥ࡜ྠᵝ࡛࠶ࡾࠊV/III ẚࡢ᭱㐺್ࡣᡂ㛗ᅽຊ࡟ࡼࡗ࡚ኚ໬ࡍࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋ࣮࣮࢟࣡ࢻ㸸 ࣘ࢘ࣟࣆ࣒࢘ࠊ❅໬࣒࢞ࣜ࢘ࠊ㉥ⰍⓎගࢹࣂ࢖ࢫ⫼ᬒ࡜◊✲┠ⓗ㸸GaN ⣔ᮦᩱࡣ࣡࢖ࢻࢠࣕࢵࣉࢆ᭷ࡋࠊ㟷Ⰽࡸ⥳ⰍⓎගࢲ࢖࣮࢜ࢻ㻔LED㻕ࢆᵓᡂࡍࡿ༙ᑟయᮦᩱ࡜ࡋ࡚ᐇ⏝໬ࡉࢀࠊ⾤㢌࡛ぢ࠿ࡅࡽࢀࡿࡼ࠺࡞኱⏬㠃ࣇ࣮ࣝ࢝ࣛLED ࢹ࢕ࢫࣉࣞ࢖࡞࡝࡟ᛂ⏝ࡉࢀ࡚࠸ࡿࠋࡇࢀࡲ࡛ࠊ㉥Ⰽ LED ࡟ࡣ GaN ⣔௨እࡢࠊGaAs ᇶᯈୖ࡟ᡂ㛗ࡉࢀࡓ AlGaInP ࡀ⏝࠸ࡽࢀ࡚ࡁࡓࠋ୍᪉ࠊGaN ⣔ᮦᩱࢆ⏝࠸࡚ࠊ㉥Ⰽ LED ࡀᐇ⌧ࡍࢀࡤࠊྠ୍ᮦᩱ࡟ࡼࡿගࡢ୕ཎⰍⓎගࡀᥞ࠺ࡓࡵࠊ༙ᑟయᚤ⣽ຍᕤᢏ⾡ࢆ⏕࠿ࡋࡓࣔࣀࣜࢩࢵࢡᆺ㧗⢭⣽ LED ࢹ࢕ࢫࣉࣞ࢖ࡸ LED↷᫂࡞࡝࡬ࡢᛂ⏝ࡀྍ⬟࡜࡞ࡿࠋࡇࡢࡓࡵࠊGaN ⣔ᮦᩱࢆ⏝࠸ࡓ㉥ⰍⓎගࢹࣂ࢖ࢫࡢᐇ⌧ࡣࠊ⏘ᴗⓗ࡟ᴟࡵ࡚㔜せ࡞◊✲ㄢ㢟࡜࡞ࡗ࡚࠸ࡿࠋࡇ࠺ࡋࡓ⫼ᬒ࠿ࡽࠊGaN ⣔ᮦᩱ࡟ࡼࡿ㉥Ⰽ LED ᐇ⌧࡟ྥࡅ࡚ࠊ㟷Ⰽ࣭⥳Ⰽ LED ࡛άᛶᒙ࡜ࡋ࡚⏝࠸ࡽࢀ࡚࠸ࡿ InGaN ΰᬗ⣔ࡢ㧗 In ⤌ᡂ໬ࢆ┠ᣦࡋࡓ◊✲ࡀ⢭ຊⓗ࡟⾜ࢃࢀ࡚࠸ࡿࡀࠊInGaN/GaN 㛫ࡢ᱁Ꮚ୙ᩚྜ࡟㉳ᅉࡍࡿ⤖ᬗရ㉁ࡢຎ໬ࡀ῝้࡞ㄢ㢟࡛࠶ࡿࠋ୍᪉ࠊࣘ࢘ࣟࣆ࣒࢘㻔Eu㻕࢖࢜ࣥࡣ 3 ౯ࡢ≧ែ࡛㉥Ⰽ㡿ᇦ࡟ගᏛ㑄⛣ࢆ᭷ࡍࡿࡓࡵࠊGaN ࢆ⏝࠸ࡓ㉥ⰍⓎගᮦᩱࡢⓎග୰ᚰ࡜ࡋ࡚ὀ┠ࡉࢀ࡚࠸ࡿࠋEu ῧຍ GaN స〇᪉ἲ࡜ࡋ࡚ࠊ࢖࢜ࣥὀධἲ࡜ศᏊ⥺࢚ࣆࢱ࢟ࢩࣕࣝἲཬࡧᡃࠎࡢ᭷ᶵ㔠ᒓẼ┦࢚ࣆࢱ࢟ࢩࣕࣝἲࡀᏑᅾࡍࡿࡀࠊ࢖࢜ࣥὀධἲࡸศᏊ⥺࢚ࣆࢱ࢟ࢩࣕࣝἲ࡛ࡣࠕࢹࣂ࢖ࢫရ㉁ࡢ Eu ῧຍ GaNࠖࢆస〇ࡍࡿࡇ࡜ࡀᅔ㞴࡛࠶ࡾࠊࡑࡢస〇ᡭἲ⮬యࡢᐇ⏝ᛶ࡟ࡶ኱ࡁ࡞ㄢ㢟ࢆᢪ࠼࡚࠸ࡿࠋ୍᪉ࠊᡃࠎࡣࠊ᭷ᶵ㔠ᒓẼ┦࢚ࣆࢱ࢟ࢩࣕࣝἲࢆ⏝࠸࡚ 2࢖ࣥࢳࢧ࢖ࢬࡢࢧࣇ࢓࢖࢔ᇶᯈୖ࡟ᆒ୍࡟ Eu ῧຍ GaN ࢆస〇ࡍࡿࡇ࡜࡟ᡂຌࡋࠊGaN ⣔㉥ⰍLED ࡢᐊ ືసࢆୡ⏺࡟ඛ㥑ࡅ࡚ᐇ⌧ࡋ࡚࠸ࡿ[1, 2]ࠋࡼࡗ࡚ࠊGaN ⣔㉥Ⰽ LED ࡢᐇ⏝໬࡟ྥࡅ࡚ࠊ⌧≧ࡢᩘ༑PW ࡢගฟຊࢆ mW ⛬ᗘࡲ࡛ቑ኱ࡉࡏࡿࡇ࡜࡟᭱ᚋࡢㄢ㢟ࡀ⤠ࡽࢀ࡚ࡁ࡚࠸ࡿࠋEu Ⓨගࡣࠊῧຍࡉࢀࡓ Eu ࢖࢜ࣥཎᏊࡢ࿘㎶ᒁᡤᵓ㐀࡟ࡼࡿ⤖ᬗሙ࡟ࡼࡗ࡚Ⓨගຠ⋡ࡀኚ໬ࡍࡿࠋ
ࡇࡢࡓࡵࠊEu Ⓨගᙉᗘࡢᨭ㓄せᅉࡢゎ᫂࡟ࡣࠊGaN ୰࡟࠾ࡅࡿ Eu ࢖࢜ࣥࡢ࿘㎶ᒁᡤᵓ㐀ࢆゎᯒࡍࡿࡇ࡜ࡀ୙ྍḞ࡛࠶ࡿࠋ ᮏᐇ㦂࡛ࡣࠊ᭷ᶵ㔠ᒓẼ┦࢚ࣆࢱ࢟ࢩࣕࣝἲ࡟ࡼࡗ࡚స〇ࡋࡓ Eu ῧຍ GaN ࡟࠾࠸࡚ࠊX ⥺྾཰ᚤ⣽ᵓ㐀㻔XAFS㻕 ᐃ࡟ࡼࡾ Eu ῧຍࢧ࢖ࢺ࠾ࡼࡧࡑࡢ࿘㎶ᒁᡤᵓ㐀ࢆ᫂ࡽ࠿࡟ࡍࡿࡇ࡜ࢆ┠ⓗ࡜ࡍࡿࠋ⤖ᬗᡂ㛗᮲௳࠾ࡼࡧⓎගᙉᗘ࡜ Eu ཎᏊࡢῧຍࢧ࢖ࢺ࠾ࡼࡧࡑࡢ࿘㎶ᒁᡤᵓ㐀ࡢ㛵ಀࢆゎ᫂ࡋࠊ᭷ᶵ㔠ᒓẼ┦࢚ࣆࢱ࢟ࢩࣕࣝἲ࡟ࡼࡗ࡚ῧຍࢧ࢖ࢺࢆ⢭ᐦ࡟ไᚚࡋࠊ㧗㍤ᗘ Eu Ⓨගࡢᐇ⌧ࢆ┠ᣦࡍࠋᐇ㦂㸸ᮏᐇ㦂࡛ࡣࠊ᭷ᶵ㔠ᒓẼ┦࢚ࣆࢱ࢟ࢩࣕࣝἲ࡟ࡼࡾస〇ࡋࡓ Eu ῧຍ GaN ᒙࢆ ᐃヨᩱ࡜ࡋ࡚⏝࠸ࡓࠋヨᩱᵓ㐀ࡣࢧࣇ࢓࢖࢔ᇶᯈୖ࡟ప GaN ࣂࢵࣇ࢓ᒙࠊ↓ῧຍ GaN ᒙࢆ✚ᒙࡋࠊEu ῧຍGaN ᒙࢆ 400 nm ✚ᒙࡋࡓࡶࡢ࡛࠶ࡿࠋV/III ẚ㸦III ᪘ཎᩱ࡛࠶ࡿ TMGa ࡟ᑐࡍࡿࠊV ᪘ཎᩱ࡛࠶
ࡿ NH3 ࡢࣔࣝẚ㸧ࢆ 6400 ࡜ᅛᐃࡋࠊEu ῧຍ GaN ᒙᡂ㛗᫬ࡢᡂ㛗ᅽຊࢆ 40, 70, 100 kPa ࡜ኚ໬ࡉࡏࡓヨᩱࢆ‽ഛࡋࡓࠋࣇ࢛ࢺ࣑ࣝࢿࢭࣥࢫ㻔PL㻕 ᐃࡢ⤖ᯝࡼࡾࠊ40 kPa ࡟࡚ᡂ㛗ࡋࡓヨᩱ࠿ࡽࡣⓎගࣆ࣮ࢡࡢࣈ࣮ࣟࢻ໬㸦್༙ᖜ 3.60 nmࠊ100 kPa ヨᩱࡢࡶࡢࡣ 2.17 nm㸧ࡀほ ࡉࢀ࡚࠸ࡿࠋ
ࡇࢀࡽࡢ PL ᐃ⤖ᯝ࡜࿘㎶ᒁᡤᵓ㐀ࡢ㛵ಀࢆ᫂ࡽ࠿࡟ࡍࡿࡓࡵࠊXAFS ᐃࢆ⾜ࡗࡓࠋᑦࠊXAFS
ᐃࡣ࠸ࡎࢀࡢヨᩱࡶ⺯ගἲ࡟࡚⾜ࡗࡓࠋ

Eu Concentration (cm-3)⤖ᯝ࠾ࡼࡧ⪃ᐹ㸸
ᅗ 1 ࡟ᡂ㛗ᅽຊࢆ 40, 70, 100 kPa ࡜ኚ໬ࡉࡏ࡚స〇ࡋࡓ Eu ῧຍ GaN ࡟࠾ࡅࡿᨺᑕග⺯ග X ⥺ᐃ⤖ᯝࢆ♧ࡍࠋ⺯ග X ⥺ᙉᗘࡣ Eu ⃰ᗘ࡟ẚ౛ࡋ࡚࠾ࡾࠊᡂ㛗ᅽຊࢆపୗࡉࡏࡿࡇ࡜࡟ࡼࡗ࡚Eu ⃰ᗘࡀቑຍࡍࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋSIMS ᐃ࡟ࡼࡗ࡚ Eu ⃰ᗘࡀྠᐃࡉࢀ࡚࠸ࡿヨᩱࢆᶆ‽ヨᩱ࡜ࡋ࡚ࠊ௒ᅇస〇ࡋࡓヨᩱࡢ Eu ⃰ᗘࢆィ⟬ࡍࡿ࡜ᡂ㛗ᅽຊࡢῶᑡ࡟ࡼࡾࠊ5.9x1019 cm-3㻔100 kPa㻕࠿ࡽ 9.5x1019 cm-3㻔40 kPa㻕࡜ Eu ⃰ᗘࡀቑ኱ࡋ࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋࡇࢀࡣࠊῶᅽ᮲௳࡟࡚ᡂ㛗ࢆ⾜࠺ࡇ࡜࡟ࡼࡗ࡚ࠊEu ᭷ᶵཎᩱࡢ㣬࿴⵨Ẽᅽࡀቑ኱ࡋࠊEu ౪⤥㔞ࡀቑ኱ࡋࡓࡓࡵ࡛࠶ࡿ࡜⪃࠼ࡽࢀࡿࠋḟ࡟ࠊୖグ 3 ヨᩱ࡟ࡘ࠸࡚ XAFS ᐃࢆ⾜࠸ࠊࡑࡢືᚄᵓ㐀㛵ᩘࢆᅗ 2 ࡟♧ࡍࠋᡂ㛗ᅽຊࢆ 40 kPa
࡜ࡍࡿࡇ࡜࡟ࡼࡾ➨஧㏆᥋ཎᏊ࡛࠶ࡿ Ga ࡢࣆ࣮ࢡࡀ㢧ⴭ࡟ῶᑡࡋࡓࠋ࣮࢝ࣈࣇ࢕ࢵࢸ࢕ࣥࢢࡢ
⤖ᯝࠊᡂ㛗ᅽຊ 40 kPa ࡢヨᩱࡢ Debye-Waller ᅉᏊࡀ⣙ 0.10ύ࡜௚ࡢ 2 ヨᩱࡢ್⣙ 0.08ύ࡟ẚ࡭࡚ቑ኱ࡋ࡚࠾ࡾࠊGa ࡢ఩⨨ᦂࡽࡂࡀቑ኱ࡋ࡚࠸ࡿࡇ࡜ࡀศ࠿ࡗࡓࠋPL ᐃ࡟ࡼࡿⓎගࢫ࣌ࢡࢺࣝ
ࡣ 40 kPa ࡛ࡣ㢧ⴭ࡞ࣈ࣮ࣟࢻ໬ࡀぢࡽࢀࡿࡇ࡜࠿ࡽࠊୖ㏙ࡋࡓ Eu ࿘㎶ᒁᡤᵓ㐀ࡢኚ໬ࡀ PL ≉ᛶ࡟ᙉࡃᙳ㡪ࢆ୚࠼࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋࡇࡢ㛵ಀࡣᅗ 3 ࡟♧ࡍࡼ࠺࡟ V/III ẚࢆ᭱㐺್㻔6400㻕
ࡼࡾ 9600 ࡬ቑຍࡉࡏࡓ࡜ࡁ࡟ࡶྠᵝ࡟ほ ࡉࢀ࡚࠸ࡿࡓࡵࠊῶᅽ᮲௳࡟࠾ࡅࡿ⤖ᬗᡂ㛗࡛ࡣᐇຠⓗ࡞ V/III ẚࡀኚ໬ࡋ࡚࠸ࡿྍ⬟ᛶࡀ࠶ࡾࠊᡂ㛗ᅽຊࡈ࡜࡟ V/III ẚࢆ᭱㐺໬ࡍࡿᚲせࡀ࠶ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋ

GaN:Eu6 1019
5.2x1019

5 10193 10192.3x1019

2 10190Elastic
scattering1.3x1019

1 10195.2x1018
0481216

Eu LDIntensity (a.u.)

Eu LD40 kPa

Eu LE70 kPa
100 kPa

55.566.5

77.5

8

8.5

70 kPaF.T.{k3F(k)} (arb. unit)

X-ray Intensity (a.u.)       

Eu-Ga
100 kPa4 10199Energy (eV)ᅗ 1. ᨺᑕග⺯ග X ⥺࡟ࡼࡿ Eu ⃰ᗘࡢᡂ㛗ᅽຊ౫Ꮡᛶ㸦ᤄධᅗ㸸ᶆ‽ヨᩱ࡟ࡼࡿᰯṇ᭤⥺㸧

40 kPa

Eu-N

0

1234

RADIAL DISTANCE (Å)

56

ᅗ 2. 40, 70, 100 kPa ࡟࡚స〇ࡋࡓEu ῧຍ GaN ࡟࠾ࡅࡿືᚄᵓ㐀㛵ᩘ

(a)

Eu-Ga

F.T.{k3F(k)} (arb. unit)

V/III = 3200V/III = 6400

V/III = 9600

Eu-N

01234

RADIAL DISTANCE (Å)

56ᅗ 3. V/III ẚࢆኚ໬ࡉࡏࡓ Eu ῧຍ GaN ࡟࠾ࡅࡿ㻔a㻕ືᚄᵓ㐀㛵ᩘࠊ㻔b㻕ࣇ࢛ࢺ࣑ࣝࢿࢭࣥࢫࢫ࣌ࢡࢺࣝ
௒ᚋࡢㄢ㢟㸸 ௒ᅇࡢ ᐃ⤖ᯝ࡟ࡼࡾࠊᡂ㛗ᅽຊࢆῶᑡࡉࡏࡿࡇ࡜࡟ࡼࡾ Eu ⃰ᗘࡀቑ኱ࡋࠊ➨஧㏆᥋ཎᏊ࡛࠶ࡿ Ga ࡢ఩⨨ᦂࡽࡂࡀቑ኱ࡍࡿࡇ࡜ࡀ᫂ࡽ࠿࡜࡞ࡗࡓࠋࡲࡓࠊࡇࡢ࿘㎶ᒁᡤᵓ㐀ࡢኚ໬ࡣࣇ࢛
ࢺ࣑ࣝࢿࢭࣥࢫࣆ࣮ࢡᖜ࡟ᙉࡃᙳ㡪ࢆ୚࠼ࡿࠋV/III ẚࢆኚ໬ࡉࡏࡓヨᩱ࡜ྜࢃࡏ࡚⪃ᐹࡍࡿ࡜ࠊ
ᡂ㛗᮲௳ࡀኚ໬ࡋࡓ࡜ࡁࡢᐇຠⓗ࡞ V/III ẚࡀ Eu Ⓨග࡟ᙉࡃᙳ㡪ࡍࡿࡇ࡜ࡀࢃ࠿ࡿࡓࡵࠊEu ࢖࢜ࣥ࡟ࡼࡿ㧗㍤ᗘⓎගࢆᐇ⌧ࡍࡿࡓࡵ࡟ࡣ㧗 Eu ⃰ᗘࡀᐇ⌧࡛ࡁࡿῶᅽ᮲௳࡟࠾࠸࡚ࠊࡉࡽ࡞ࡿ V/IIIẚࡢ᭱㐺໬ࡀ㔜せ࡛࠶ࡿࠋཧ⪃ᩥ⊩㸸
[1] A. Nishikawa, T. Kawasaki, N. Furukawa, Y. Terai, and Y. Fujiwara, Appl. Phys. Exp. 2, 071004
㻔2009㻕.
[2] A. Nishikawa, T. Kawasaki, N. Furukawa, Y. Terai, and Y. Fujiwara, Phys. Status Solidi A 207, 1938
㻔2010㻕.