JPH01106475A - Sic blue color light emitting diode - Google Patents

Abstract

PURPOSE:To increase the density of carriers at the area where electrons and positive holes are recombined by arranging a 6H-SiC layer showing a reverse conduction type in reference with the 4H-SiC layer on the main surface of 4H-SiC layer of one conduction type. CONSTITUTION:Aluminum doped p-type 4H-SiC layer 22 and aluminum and nitrogen doped n-type 6H-SiC layer 23 are laminated on a p-type 4H-SiC substrate 21 in sequence and the first and second ohmic electrodes 24 and 25 are formed on the rear surface of a substrate 21 and the front surface of n-type 6H-SiC layer 23. It allows an electron 29 which is located at a conductive band 27 or a donor level 33 and a positive hole 32 which is located at an acceptor level 34 in n-type 6H-SiC layer 23 near a junction 26 to be recombined, thus emitting a blue light with a wavelength of 480nm. At this time, since injection of the electron 29 into the p-type 4H-SiC layer is prevented by a barrier 28 of a conductive band 27, the n-type 6H-SiC layer 23 near the junction 26 where the electron 29 and the positive hole 32 are recombined becomes an area where the electron 29 exists in high concentration. Thus, in this kind of area, recombination efficiency of the electron 29 and the positive hole 32 improves and as a result the emission efficiency improves.

Description

【発明の詳細な説明】 （イ）産業上の利用分野 本発明はＳ２Ｏ青色発光ダイオードに関する。[Detailed description of the invention] (b) Industrial application fields The present invention relates to S2O blue light emitting diodes.

（ロ）従来の技術 ６Ｈ−８１０はバンドギャップが大きく、ｐｎ両伝導形
が得られることから青色発光ダイオード用材料として注
目を浴びてきた。(b) Conventional technology 6H-810 has a large band gap and has attracted attention as a material for blue light emitting diodes because both pn and pn conduction types can be obtained.

また、６Ｈ−ＳｉＣからなる青色発光ダイオードの発光
層はり、Ｈｏｆ＋ｍａｎｎらの報告（Ｊｏｕｒｎａｌ　
ＡｐｐｌｉＱａ　Ｐｈｙｓｉａ５　５３（１０）、６９
６２゜（１９８２））から、カッードル建ネッ七ンスを
用い比測定でｎ側エピタキシャル成長層で発光している
ことか知られている。更にＧ１１ｎｔｈＯｒ　　２１６
ｇ１６１ｍ”　　らの報告（Ｉ　Ｅ　Ｂ　Ｉ　　Ｔｒａ
ｍｓ　、　ＩＣ１ａＣｓｒｏｎ　Ｄａｖｉａｅｇ、ＥＤ
−３０，２７７（１９８３））では、アルミニウムドー
プｐ型　６Ｈ−８１０とアンドーグｎ型　６Ｈ−８１０
１に比較すると、八 アルミニウムドープｐ型　６Ｈ−８ａｃの方がか、・４
ＶＩ′ なり透過率が低いことが知られている。　　　　′これ
らの点から、Ｓｔａ青色発光ダイオードの構造としては
、一般に第５図に示す如く、ｐ型の６Ｈ−８１０基板（
１）上にアルミニウム（Ａ／）がドープされたｐ型ａ６
　ＨＳ　Ｃｏ層（２）とアルミニウム及び窒素（ト））
がドープされたｎ型６Ｈ−８１０層。In addition, a light-emitting layer of a blue light-emitting diode made of 6H-SiC was reported by Hof+mann et al. (Journal
AppliQa Physia5 53(10), 69
62° (1982)), it is known that light is emitted from the n-side epitaxially grown layer by ratio measurement using a cuddle net. Furthermore, G11nthOr 216
g161m” et al. (I E B I Tra
ms, IC1aCsron Daviaeg, ED.
-30, 277 (1983)), aluminum-doped p-type 6H-810 and undoped n-type 6H-810.
Compared to 1, 8 aluminum-doped p-type 6H-8ac is ・4
VI' is known to have a low transmittance. 'From these points, the structure of the Sta blue light emitting diode is generally based on a p-type 6H-810 substrate (as shown in Figure 5).
1) P-type a6 doped with aluminum (A/) on top
HS Co layer (2) and aluminum and nitrogen (t))
n-type 6H-810 layer doped with .

（３１とを順次積層すると共に基板（１）裏面及びｎ型
８′１０層（３）上に第１、第２のオーミック電極（４
）（５）が形成されたものが知られてい机 オードでは発光効率が低いという問題があっ念。(31) are sequentially laminated, and first and second ohmic electrodes (4
)(5) is known, but there is a problem that the luminous efficiency is low in the desk ode.

斯る原因を鋭意探究した結果、上記し九ホモ接合では第
６図にそのエネルギ図を示す如く、順方向バイアス印加
時の接合（６）がなだらかな傾斜接合となるため、実際
の発光領域となるｎ型ｅ６Ｈ−状態が生じにくく、その
結果、ｎ型８１０層（３）中へ のドナレベル（７）とアクセプタレベル（８）との間、
もしくは伝導帯（９）とアクセプタレベル（８）との間
で生じる電子αυと正孔（１ｚとの再結合効率が低くな
るためであることが判明した。As a result of intensive investigation into the cause, we found that in the above-mentioned nine homojunctions, as shown in the energy diagram in Figure 6, the junction (6) when a forward bias is applied becomes a gently sloped junction, which is different from the actual light emitting region. As a result, between the donor level (7) and the acceptor level (8) into the n-type 810 layer (3),
Alternatively, it has been found that this is because the recombination efficiency between electrons αυ and holes (1z) generated between the conduction band (9) and the acceptor level (8) becomes low.

尚、第６図中、（ＩＱは価電子帯を示し、またドナレベ
ル（７）及びアクセプタレベル（８）は夫々窒素及びア
ルミニウムによ多形成される不純物レベルであるＯ に）問題点を解決する次めの手段 本発明は斯る点に鑑みてなされ念もので、その構成的特
徴は、−導電型の４）（−８１層層の一主面に該４　Ｈ
−８１０層とは逆導電型を示す６）！−１３１０層を配
したことにある。In addition, in Figure 6, (IQ indicates the valence band, and the donor level (7) and acceptor level (8) are the impurity levels formed by nitrogen and aluminum, respectively). Next Means The present invention was made in view of the above points, and its structural features are as follows: - conductivity type 4) (-81)
It exhibits a conductivity type opposite to that of the -810 layer 6)! -This is because 1310 layers are arranged.

（ホ）作　用 このような構成では、４　Ｈ−Ｂ　ｉ　０層と６　Ｈ−
Ｂ　１０層との禁制帯幅に差があるため、順方向バイア
ス印加時に上記両層の接合部にエネルギ障壁が生じる。(e) Effect In such a configuration, the 4 H-B i 0 layer and the 6 H-
Since there is a difference in the forbidden band width with the B10 layer, an energy barrier is generated at the junction between the two layers when a forward bias is applied.

（へ）実施例 第１図は本発明の第１の実施例を示し、ｐ全４Ｈ−Ｓｉ
Ｃ基板Ｃ！υ上にアルミニウムドープのｐ全４Ｈ−Ｓｉ
Ｃ層のと、アルミニウム及び窒素がドープされ九ｎ型６
Ｈ−８１０層（ハ）とを順次積層すると共に基板ＱＤ裏
面及びｎ型６Ｈ−ｓ１ｏＨ１＠表面に第１、第２オーミ
ツク電極Ｇ！４）（２５１を形成してなドのｐｎ接合（
至）近傍のエネルギ状態を示し、具体、。(f) Example FIG. 1 shows the first example of the present invention, in which p-all 4H-Si
C board C! Aluminum doped p all 4H-Si on υ
The C layer is doped with aluminum and nitrogen and is of N-type 6
H-810 layers (c) are sequentially laminated, and first and second ohmic electrodes G! 4) (251 is formed and the pn junction (
to) indicates the energy state of the neighborhood, concrete.

的には第２図Ｃりは熱平衡時のエネルギ状態を、又第２
図ｃ′ｂ）は頭方向バイアス印加時のエネルギ状態を夫
々示す０ 第２図ｅ）に示す如く、ｐ全４Ｈ−８１０層Ωの禁シ」
帯幅は約１２７ｅＶであシ、又ｎ型６Ｈ−３１層（ハ）
の禁ＩＩ帯幅は約５．０２ｅｖである。このため、順方
向バイアスを印加すると第２図（１））に示す如く、伝
導帯（５）側に高さ約０．２８’／の障壁（至）が発生
する。従って、ｎ型６Ｈ−ＳｉＣ層［有］からｐ全４Ｈ
−８１０層四への電子−の注入はその大部分が斯る障壁
（２）により阻止される。尚、このとき価電子帯（至）
側にも障壁Ｇυが生じるが、斯る障壁Ｃ１１ｌは非常に
低いため、正孔国はｐ全４Ｈ−８１０層＠からｎ型６Ｈ
−８４ＬＯ層（至）へ効率良く注入される。Specifically, Figure 2C shows the energy state at thermal equilibrium, and the second
Figure c'b) shows the energy state when applying a bias in the head direction.
The band width is about 127 eV, and the n-type 6H-31 layer (c)
The forbidden II band width of is about 5.02ev. Therefore, when a forward bias is applied, a barrier with a height of about 0.28'/cm is generated on the conduction band (5) side, as shown in FIG. 2 (1). Therefore, from the n-type 6H-SiC layer [present] to the p-all 4H
The injection of electrons into the -810 layer 4 is mostly blocked by such a barrier (2). In addition, at this time, the valence band (to)
A barrier Gυ also occurs on the side, but since the barrier C11l is very low, the hole country is changed from the p-all 4H-810 layer @ to the n-type 6H
-84 Efficiently injected into the LO layer (to).

この結果、本実施例装置では接合（ハ）近傍のｎ型６ｎ
−ｓｉ０４ｒ２３中で伝導帯Ｑηもしくはドナレベル（
至）に位置する電子のとアクセプタレベル（財）に位置
する正孔ｒ３４とが再結合し、エネルギｈｖ＋２．６ｅ
ｖの光、即ち波長４８０ｎｍの青色光を発することとな
る。また、このとき伝導帯Ｑηの障壁−によりｐ全４Ｈ
−ＳｉＣ層のへの電子のの注入が阻止される友め、電子
囚と正孔ｃ１４とが再結合する接合（ハ）近傍のｎ型６
Ｈ−８１０層Ｑは電子のが高密度に存在する領域となる
。従って、斯る領域では従来に較べて電子のと正孔■と
の再結合効率が向上し、その結果発光効率も向上する。As a result, in the device of this embodiment, the n-type 6n near the junction (c)
-conduction band Qη or donor level (
The electron located at
It emits light of 480 nm, that is, blue light with a wavelength of 480 nm. Also, at this time, due to the barrier of the conduction band Qη, p total 4H
- n-type 6 near the junction (c) where electrons are prevented from being injected into the SiC layer, and where electron prisoners and holes recombine
The H-810 layer Q is a region where electrons exist at a high density. Therefore, in such a region, the recombination efficiency of electrons and holes is improved compared to the conventional case, and as a result, the luminous efficiency is also improved.

尚、第２図中、ドナレベル儲及びアクセプタレベル（ロ
）は夫々不純物としてドープされた窒素もしくはアルミ
ニウムが形成するレベルであるＯｎ型４Ｈ−８１ｃＪＨ
ｔ２１とアルミニウム及び窒素が区 ドープされたｐ型６）！−８１０層（４３とを順次積層
すると共に基板α０表面及びｐ全６Ｈ−ＳｉＣ層（４３
表面に第１、第２オーミツク電極Ω４）ＱＳｔ−形成し
てドのｐｎ接合（ハ）近傍のエネルギ状態を示し、具体
的には第４図（ＩＬ）は熱平衡時のエネルギ状態を、又
第４図（ロ）は頭方向バイアス印加時のエネルギ状態を
夫々示す。In Fig. 2, the donor level and acceptor level (b) are levels formed by nitrogen or aluminum doped as an impurity, respectively.On type 4H-81cJH
p-type doped with t21 and aluminum and nitrogen 6)! -810 layers (43) are laminated in sequence, and the substrate
First and second ohmic electrodes Ω4)QSt- are formed on the surface to show the energy state near the pn junction (c) of the do. Specifically, FIG. 4 (IL) shows the energy state at thermal equilibrium, and Figure 4 (b) shows the energy states when applying a bias in the head direction.

第４図（ａ）　Ｋ示す如く、ｎ型４ａ−ｓｉｏｆｆｉｌ
Ｑ３の禁制帯幅は約３４７ｅＶで１）、又ｐ型６Ｈ−８
１０層（４３の禁制帯幅は約４〇２８Ｖである。このた
め、順方向バイアスを印加すると、第４図ゆ）に示す如
く価電子帯０η側に高さ約０．２８Ｖの障壁にか発生す
る。従って、ｐ全６Ｈ−１３１０層Ｇｔ３からｎ型４Ｈ
−８１０層（４３への正孔四の注入はその大部分が斯る
障壁囮によシ阻止される０尚、このとき伝導帯ω側にも
障壁（５１）が生じるが、斯る障壁（５１）は非常に低
いため、電子（５２）はｎ型４Ｈ−８１０層（４渇から
ｐ型６ｕ−ｓｔｃ層（４３へ効率良く注入される。Figure 4(a) As shown in K, n-type 4a-sioffil
The forbidden band width of Q3 is approximately 347eV1), and p-type 6H-8
The forbidden band width of the 10 layer (43) is about 4028 V. Therefore, when a forward bias is applied, a barrier with a height of about 0.28 V is formed on the valence band 0η side as shown in Figure 4. Occur. Therefore, from p-all 6H-1310 layer Gt3 to n-type 4H
Most of the injection of holes into the −810 layer (43) is blocked by such a barrier decoy.0 At this time, a barrier (51) is also generated on the conduction band ω side; 51) is very low, electrons (52) are efficiently injected from the n-type 4H-810 layer (43) to the p-type 6U-stc layer (43).

この結果、本実施例装置では接合（ト）近傍のｐ型６Ｈ
−３１０層（４３中で伝導帯ωもしくはドナレベル（５
３）に位置する電子（５２）とアクセプタレベル（５４
）に位置する正孔（４１とが再結合し、エネルギ状態中
２，６θＶの光、即ち波長４８０ｎｍの青色光を発する
こととなる。ま九、このとき価電子帯（４ηの障壁■に
よりｎ型４Ｈ−ＳｉＣ層（４２中への正孔（４９の注入
が阻止されるため、電子（５２）と正孔四とが再結合す
る接合（１６１近傍のｐ型６Ｈ−８ＬＯＪｌ（４３は正
孔晴が高密度に存在する領域となる。従って、斯る領域
では従来に較べて１子（５２）と正孔四との再結合効率
が向上し、その結果発光効率も向上する。As a result, in the device of this embodiment, the p-type 6H near the junction (G)
-310 layers (conduction band ω or donor level (5
3) and the electron (52) located at the acceptor level (54)
) is recombined with the hole (41), and light of 2,6θV in the energy state, that is, blue light with a wavelength of 480nm, is emitted. Type 4H-SiC layer (p-type 6H-8LOJl near 161 (p-type 6H-8LOJl (43 is hole This is a region where holes exist at a high density.Therefore, in such a region, the recombination efficiency between the 1st hole (52) and the 4th hole is improved compared to the conventional case, and as a result, the luminous efficiency is also improved.

尚、ドナレベル（５３）及びアクセプタレベル（４′ｒ
Ｉは不純物としてドープされた窒素とアルニウムとによ
り形成されるレベルである。In addition, the donor level (53) and acceptor level (4'r
I is the level formed by nitrogen and aluminum doped as impurities.

（ト）発明の効果 本発明によれば、電子と正孔とが再結合を生じる領域に
おけるキャリアの高密度化がはかれるので従来に比して
高効率で青色光を発生することができる。(G) Effects of the Invention According to the present invention, the density of carriers in the region where electrons and holes recombine can be increased, so that blue light can be generated with higher efficiency than in the past.

【図面の簡単な説明】[Brief explanation of the drawing]

の 第１図は本発明の第１Ａ実施例を示す断面図、第２図（
ＳＬ）Ｃｂ）は第１実施例のエネルギ状態を示す模式図
、第３図は本発明の第２の実施例を示す断面図、第４図
（１ｋ）（ｂ）は第２実施例のエネルギ状態を示す模式
図、第５図及び第６図は夫々従来例を示す断面図及びそ
のエネルギ状態を示す模式図である。 ＠　・　ｐ型４Ｈ−ＳｉＣ層、Ｑ！３・ｎ型６Ｈ−Ｓｉ
Ｃ層、（４３・ｎ型４１’ｌ−Ｂ　ｉ　０層、（４３−
Ｐ型６Ｈ−８１０層。1 is a sectional view showing the 1A embodiment of the present invention, and FIG. 2 (
SL)Cb) is a schematic diagram showing the energy state of the first embodiment, FIG. 3 is a sectional view showing the second embodiment of the present invention, and FIGS. 4(1k) and (b) are schematic diagrams showing the energy state of the second embodiment. 5 and 6 are a cross-sectional view showing a conventional example and a schematic diagram showing its energy state, respectively. @ ・ p-type 4H-SiC layer, Q! 3.n-type 6H-Si
C layer, (43・n type 41'l-B i 0 layer, (43-
P type 6H-810 layer.

Claims (1)

【特許請求の範囲】[Claims] （１）一導電型の４Ｈ−ＳｉＣ層の一主面に該４ＨＳｉ
Ｃ層とは逆導電型を示す６Ｈ−ＳｉＣ層を配したことを
特徴とするＳｉＣ青色発光ダイオード。(1) The 4HSi on one main surface of the 4H-SiC layer of one conductivity type.
An SiC blue light emitting diode characterized by having a 6H-SiC layer having a conductivity type opposite to that of the C layer.