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2011A1747

         BL14B2X ⥺྾཰ᚤ⣽ᵓ㐀 ᐃ࡟ࡼࡿ Eu ῧຍ GaN ࡟࠾ࡅࡿEu ࢖࢜ࣥࡢ࿘㎶ᒁᡤᵓ㐀㻔IV㻕Local Structures around Eu Ions in GaN Studiedby X-ray Absorption Fine Structure 㻔IV㻕⸨ཎ ᗣᩥ a, すᕝ ᩔ a, ᮤ ᮾᘓ a, ᯇ㔝 Ꮥ๎ a, 㛗㇂ᕝ ு௓ a, ኱ῲ ༤ᐉ b, ᮏ㛫 ᚭ⏕ b
Yasufumi Fujiwaraa, Atsushi Nishikawaa, Dongun Leea, Takanori Matsunoa, Ryosuke Hasegawaa,
Hironori Ofuchib, Tetsuo Honmaba኱㜰኱Ꮫ, b㻔㈈㻕㧗㍤ᗘග⛉Ꮫ◊✲ࢭࣥࢱ࣮ aOsaka University, b JASRI᭷ᶵ㔠ᒓẼ┦࢚ࣆࢱ࢟ࢩࣕࣝἲ࡟ࡼࡾస〇ࡋࡓ Eu ῧຍ GaN ヨᩱࡢ࿘㎶ᒁᡤᵓ㐀ࢆ X ⥺྾཰ᚤ⣽ᵓ㐀㻔XAFS㻕 ᐃ࡟ࡼࡾㄪ࡭ࡓࠋEu Ⓨගࡣ Eu ࢖࢜ࣥῧຍࢧ࢖ࢺࡢᑐ⛠ᛶ࡟ࡼࡾⓎග㑄⛣☜⋡ࡀ኱ࡁࡃኚ໬ࡍࡿࡓࡵࠊAl ཬࡧ Mg ࢆពᅗⓗ࡟ඹῧຍࡋࠊEu ῧຍࢧ࢖ࢺࡢᑐ⛠ᛶไᚚࢆ⾜ࡗࡓࠋXAFS ᐃࡢ⤖ᯝࠊẕయᮦᩱࡢ Al ⤌ᡂࢆቑ኱ࡉࡏࡿ࡜࡜ࡃ࡟஧౯ࡢ Eu ࡟┦ᙜࡍࡿࣆ࣮ࢡࡀ⏕ࡌࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋࡲࡓࠊMg ඹῧຍ࡛ࡣືᚄᵓ㐀㛵ᩘ࡟࠾ࡅࡿࣆ࣮ࢡᙉᗘࡀῶᑡࡋ࡚࠾ࡾࠊMgࢆඹῧຍࡍࡿࡇ࡜࡟ࡼࡾ Eu ࢖࢜ࣥࡢ࿘㎶ᒁᡤᵓ㐀ࡢᆒ୍ᛶࡀపୗࡋ࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋࡑࢀ
ࡒࢀࡢヨᩱ࡟ࡘ࠸࡚ᨺᑕග⺯ග㹖⥺ ᐃࢆ⾜࠺ࡇ࡜࡟ࡼࡾࠊ0.1%࣮࢜ࢲ࣮࡜ᚤ㔞ῧຍࡉࢀࡓ Eu⃰ᗘࢆ㧗⢭ᗘ࡛ྠᐃࡍࡿࡇ࡜ࡀ࡛ࡁࡓࠋ࣮࣮࢟࣡ࢻ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࢖࢜ࣥࡣ୕౯ࡢ≧ែ࡛㉥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⥺࢚ࣆࢱ࢟ࢩ
ࣕࣝἲ࡛ࡣࠕࢹࣂ࢖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࡜࡟ᡂຌࡋࠊ
GaN ⣔㉥Ⰽ LEDࡢᐊືసࢆୡ⏺࡟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໬ࡍࡿࠋࡇࡢࡓ
ࡵࠊEu Ⓨ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 Al ཬࡧ Mg ࢆඹῧຍࡋࡓ Eu ῧຍAlGaN ᒙཬࡧ Eu,Mg ඹῧຍ GaN ᒙࢆᐃヨᩱ࡜ࡋ࡚⏝࠸ࡓࠋヨᩱᵓ㐀ࡣࢧࣇ࢓࢖࢔ᇶᯈୖ࡟ప

GaN ࣂࢵࣇ࢓ᒙࠊ↓ῧຍ GaN ᒙࢆ✚ᒙࡋࠊEu ῧຍ AlGaN ᒙࡲࡓࡣ Eu,Mg ඹῧຍ GaN ᒙࢆ 400
nm ✚ᒙࡋࡓࡶࡢ࡛࠶ࡿࠋAlGaN ᒙࡢ Al ⤌ᡂࡣ 0%࠿ࡽ 40%ࡲ࡛ኚ໬ࡉࡏ࡚࠾ࡾࠊMg ඹῧຍヨᩱ࡟࠾ࡅࡿ Mg ⃰ᗘࡣ 5x1019 cm-3 ࡛࠶ࡿࠋࣇ࢛ࢺ࣑ࣝࢿࢭࣥࢫ㻔PL㻕 ᐃࡢ⤖ᯝࡼࡾࠊAl ῧຍ࡟ࡼࡿ
Ⓨගᙉᗘࡢቑ኱ࡀ Al ⤌ᡂ 24%ࡲ࡛ほࡉࢀ࡚࠾ࡾࠊࡲࡓ Mg ඹῧຍ࡟ࡼࡗ࡚᪂つⓎගࣆ࣮ࢡࡀฟ

⌧ࡍࡿࡇ࡜ࡀࢃ࠿ࡗ࡚࠸ࡿࠋࡇࢀࡽࡢ PL
XAFS

ᐃࢆ⾜ࡗࡓࠋᑦࠊXAFSᐃ⤖ᯝ࡜࿘㎶ᒁᡤᵓ㐀ࡢ㛵ಀࢆ᫂ࡽ࠿࡟ࡍࡿࡓࡵࠊᐃࡣ࠸ࡎࢀࡢヨᩱࡶ⺯ගἲ࡟࡚⾜ࡗࡓࠋ㻌⤖ᯝ࠾ࡼࡧ⪃ᐹ㸸
ᅗ 1 ࡟ Eu ῧຍ AlGaN ࡟࠾ࡅࡿ Eu LIII ྾཰➃ࡢືᚄᵓ㐀㛵ᩘࢆ♧ࡍࠋAl ⤌ᡂࢆቑ኱ࡉࡏࡿ࡜ Eu࢖࢜ࣥࡢ➨஧㏆᥋ཎᏊ࡛࠶ࡿ Ga ࡜ Al ࡟ᑐᛂࡍࡿࣆ࣮ࢡࡀほࡉࢀࡓࠋࡇࢀ࡟ࡼࡾࠊAl ࢆῧຍࡍࡿࡇ࡜࡟ࡼࡗ࡚ Eu ࢖࢜ࣥࡢ࿘㎶ᒁᡤᵓ㐀࡟ኚ໬ࡀ⏕ࡌ࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋࡉࡽ࡟ᅗ 2 ࡟♧ࡍࡼ࠺࡟ Al ⤌ᡂࡢቑ኱࡟క࠸ࠊXANES 㡿ᇦ࡟࠾ࡅࡿࢫ࣌ࢡࢺࣝ࡟≉ᚩⓗ࡞ኚ໬ࡀほࡢ Eu ࡟┦ᙜࡍࡿࣆ࣮ࢡࡀ⏕ࡌࡿࡇ࡜ࡀศ࠿ࡗࡓࠋࡲࡓࠊᨺᑕග⺯ග X ⥺ྠᐃࢆ⾜ࡗࡓ⤖ᯝࠊAl ⤌ᡂ࡟㛵ࢃࡽࡎ Eu ⃰ᗘࡣ⣙ 3x1019

ᐃࢆ⾜࠸ࠊEu ⃰ᗘࡢ

-3cm ࡜୍ᐃ࡛࠶ࡾࠊEu ࡢྲྀࡾ㎸ࡳ࡟Al ⤌ᡂࡣᙳ㡪ࢆ୚࠼࡞࠸ࡇ࡜ࡀࢃ࠿ࡗࡓࠋ୍᪉ࠊࣇ࢛ࢺ࣑ࣝࢿࢭࣥࢫ
క࠸ Eu Ⓨගᙉᗘࡢቑ኱ࡀほࡉࢀࠊ஧౯ᐃ࡛ࡣࠊAl ⤌ᡂࡢቑ኱࡟

ࡉࢀ࡚࠾ࡾࠊAl ⤌ᡂ 24㸣࡟࠾࠸࡚᭱኱್ࢆ♧ࡋ࡚࠸ࡿࠋࡇࢀࡽࡢ

⤖ᯝࡼࡾࠊ஧౯ࡢ Eu ࢖࢜ࣥࡀ⏕ࡌጞࡵࡿ Al ⤌ᡂ࡜Ⓨග≉ᛶ࡟ࡣ┦㛵ࡀ࠶ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋ

ᅗ 1㸬Eu ῧຍ AlGaN ࡟࠾ࡅࡿ Eu LIII ྾཰➃ࡢືᚄᵓ㐀㛵ᩘᅗ 2㸬Eu ῧຍ AlGaN ࡟࠾ࡅࡿ⺯ග X ⥺ᙉᗘ᭤⥺㻔XANES 㡿ᇦ㻕ᅗ 3 ࡟ Mg ࢆඹῧຍࡋࡓ Eu ῧຍ GaN ࡟࠾ࡅࡿ Eu LIII ྾཰➃ࡢືᚄᵓ㐀㛵ᩘࢆ♧ࡍࠋඹῧຍࡋ
ࡓ Mg ⃰ᗘࡣ 5x1019 cm-3 ࡛࠶ࡿࠋMg ࢆῧຍࡍࡿࡇ࡜࡟ࡼࡾࠊືᚄᵓ㐀㛵ᩘࡢࣆ࣮ࢡࡀῶᑡࡋ࡚࠾
ࡾࠊEu ࢖࢜ࣥ࿘㎶ᒁᡤᵓ㐀ࡢᆒ୍ᛶࡀపୗࡋ࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡗࡓࠋࣇ࢛ࢺ࣑ࣝࢿࢭࣥࢫ⤖ᯝ࡛ࡣࠊMg ࡜ Eu ࡟ࡼࡿ」ྜయ㉳ᅉ࡜ᛮࢃࢀࡿ᪂つⓎගࣆ࣮ࢡࡀほ㛵ᩘࡢኚ໬࡜ࡢᑐᛂࡣ Mg ⃰ᗘࡲࡓࡣ Eu ⃰ᗘࡢ␗࡞ࡿヨᩱࢆᐃࡢࡉࢀ࡚࠸ࡿࡀࠊືᚄᵓ㐀ᐃࡍࡿ࡞࡝ࠊ௒ᚋ᭦࡞ࡿ᳨ウࡀᚲせ࡛࠶ࡿࠋᅗ 3㸬Mg ࢆඹῧຍࡋࡓ Eu ῧຍ GaN ࡟࠾ࡅࡿ Eu LIII ྾཰➃ࡢືᚄᵓ㐀㛵ᩘ௒ᚋࡢㄢ㢟㸸௒ᅇࡢᐃ⤖ᯝ࡟ࡼࡾࠊAl ཬࡧ Mg ୙⣧≀ࢆඹῧຍࡍࡿࡇ࡜࡟ࡼࡗ࡚ Eu ࢖࢜ࣥࡢῧຍࢧ࢖ࢺࡢᑐ⛠ᛶࢆኚ໬ࡉࡏ࿘㎶ᒁᡤᵓ㐀࡟୚࠼ࡿᙳ㡪ࢆ⣔⤫ⓗ࡟ㄪ࡭ࡿࡇ࡜ࡀ࡛ࡁࡓࠋ࡜ࡃ࡟ Al ⤌ᡂቑ኱࡟క࠸ࠊ஧౯ࡢ Eu ࡟ࡼࡿ྾཰ࡀほࡉࢀ࡚࠾ࡾࠊᕼᅵ㢮ῧຍ༙ᑟయ࡟࠾ࡅࡿⓎග≉ᛶࡢࡳ࡞ࡽࡎ☢Ẽ≉ᛶࢆ฼⏝ྍ⬟࡛࠶ࡿࡇ࡜ࢆ♧ࡋ࡚࠾ࡾࠊ኱ኚ⯆࿡῝࠸⤖ᯝࢆᚓࡿࡇ࡜ࡀ࡛ࡁࡓࠋཧ⪃ᩥ⊩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.