JPS6358383B2 - - Google Patents
Info
- Publication number
- JPS6358383B2 JPS6358383B2 JP10938979A JP10938979A JPS6358383B2 JP S6358383 B2 JPS6358383 B2 JP S6358383B2 JP 10938979 A JP10938979 A JP 10938979A JP 10938979 A JP10938979 A JP 10938979A JP S6358383 B2 JPS6358383 B2 JP S6358383B2
- Authority
- JP
- Japan
- Prior art keywords
- density
- gallium phosphide
- light
- nitrogen
- type region
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910005540 GaP Inorganic materials 0.000 claims description 59
- HZXMRANICFIONG-UHFFFAOYSA-N gallium phosphide Chemical compound [Ga]#P HZXMRANICFIONG-UHFFFAOYSA-N 0.000 claims description 53
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 32
- 229910052757 nitrogen Inorganic materials 0.000 claims description 16
- 239000012535 impurity Substances 0.000 claims description 13
- 230000004913 activation Effects 0.000 claims description 3
- 239000000758 substrate Substances 0.000 claims description 3
- 239000013078 crystal Substances 0.000 description 29
- 239000000243 solution Substances 0.000 description 20
- 238000000034 method Methods 0.000 description 18
- 229910052698 phosphorus Inorganic materials 0.000 description 14
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 13
- 239000000203 mixture Substances 0.000 description 13
- 239000011574 phosphorus Substances 0.000 description 13
- 239000000370 acceptor Substances 0.000 description 12
- 230000007547 defect Effects 0.000 description 9
- 125000004433 nitrogen atom Chemical group N* 0.000 description 8
- 230000006798 recombination Effects 0.000 description 8
- 238000005215 recombination Methods 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 3
- 239000000969 carrier Substances 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052733 gallium Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000010583 slow cooling Methods 0.000 description 3
- 125000004429 atom Chemical group 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000000110 cooling liquid Substances 0.000 description 1
- 238000002109 crystal growth method Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 125000004437 phosphorous atom Chemical group 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/26—Materials of the light emitting region
- H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
- H01L33/305—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table characterised by the doping materials
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Led Devices (AREA)
- Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
Description
【発明の詳細な説明】
本発明は半導体発光装置に関し、特に深いエネ
ルギ準位密度が低いｎ形領域を有する燐化ガリウ
ム発光装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor light emitting device, and more particularly to a gallium phosphide light emitting device having an n-type region with low deep energy level density.
燐化ガリウム（GaP）発光装置は、通常発光効
率を増すために発光中心として窒素原子を添加し
た、Ｐ形領域とｎ形領域とを含み、これらのＰ形
領域とｎ形領域とがpn接合を形成しているダイ
オード構造を有する。従来より行なわれている結
晶成長法は、主に融液ないしは溶液を徐々に冷却
して結晶を成長させる徐冷法である。これらの方
法では窒素原子を添加しないと発光効率の非常に
低いものしか得られず、従つて従来の燐化ガリウ
ム発光装置にはほとんどすべて窒素が添加してあ
り、窒素無添加で実用的な発光効率を有するもの
は見当らなかつた。 Gallium phosphide (GaP) light-emitting devices usually include a P-type region and an N-type region to which nitrogen atoms are added as luminescent centers to increase luminous efficiency, and these P-type regions and N-type regions form a p-n junction. It has a diode structure forming a . Conventionally used crystal growth methods are mainly slow cooling methods in which a melt or solution is gradually cooled to grow crystals. In these methods, only very low luminous efficiency can be obtained without the addition of nitrogen atoms. Therefore, almost all conventional gallium phosphide light-emitting devices are doped with nitrogen, and practical luminescence without the addition of nitrogen is possible. I couldn't find anything that was efficient.
ｎ形領域、Ｐ形領域のドナ密度、アクセプタ密
度の検討も、窒素原子を添加した場合についての
み行なわれていた。R.A.Logan et alの
“Efficient Green Electroluminescent
Junctions in GaP”と題する論文（Solid Stafe
Electronics 14（1971）55）は５×1017cm-3と９
×1017cm-3とのアクセプタ密度においてドナ密度
１×1016〜１×1018cm-3の範囲で窒素添加ガリウ
ム発光ダイオードをしらべ、この範囲でドナ密度
が低い程、注入発光効率は高くなる結果を得てい
る。 The donor density and acceptor density of the n-type region and the p-type region have also been studied only when nitrogen atoms are added. “Efficient Green Electroluminescent” by RALogan et al.
Junctions in GaP” (Solid Stafe
Electronics 14 (1971) 55) is 5 × 10 17 cm -3 and 9
We investigated nitrogen-doped gallium light-emitting diodes in the donor density range of 1× 10 16 to 1 ×10 18 cm -3 at an acceptor density of I am getting results.
O.G.Lorimor et alの“Very High
Efficiency GaP Green Light Emittimg
Diodes”と題する論文（J.Electrochem.Soc.
Solid−State Science and Technology 122
（1975）407）もドナ密度２×1017〜７×1017cm-3
の窒素添加燐化ガリウム発光ダイオードをしらべ
ドナ密度が低い程注入発光効率が高い結果を得て
いる。さらにドナ密度的６×1015cm-3の窒素のみ
を添加したｎ形領域を有する燐化ガリウム発光ダ
イオードに約800A／cm2の大電流を流して0.67％
という発光効率を得ている。 “Very High” by OGLorimor et al.
Efficiency GaP Green Light Emittimg
A paper entitled “Diodes” (J.Electrochem.Soc.
Solid−State Science and Technology 122
(1975) 407) also has a donor density of 2 × 10 17 to 7 × 10 17 cm -3
A study of nitrogen-doped gallium phosphide light-emitting diodes revealed that the lower the donor density, the higher the injection luminous efficiency. Furthermore, a large current of approximately 800 A/cm 2 was passed through a gallium phosphide light-emitting diode having an n-type region doped with only nitrogen at a donor density of 6×10 15 cm -3 to reduce the concentration of 0.67%.
This luminous efficiency has been achieved.
またB.L.Smith et alの“Ａ deep center
associated with the presence of nitrogen in
GaP”と題する論文（Appl.Phys.Letters 26
（1975）122）は窒素添加燐化ガリウムにおいて伝
導帯より約0.42eVの深い準位を有するトラツプ
を見出し、その密度NTとドナ密度NDとの相関が
NT＝2.5×10-20（ND−NA）2（但しNAはアクセプタ
密度）であると報告している。またこの0.42eV
の活性化エネルギを有する深い準位の密度は１×
1012〜１×1016の範囲に及んでいたと報告してい
るが、この準位の密度と発光装置の発光効率との
関連については研究されていない。 Also, “A deep center” by BLSmith et al.
associated with the presence of nitrogen in
Paper entitled “GaP” (Appl.Phys.Letters 26
(1975) 122) found a trap with a level approximately 0.42 eV deeper than the conduction band in nitrogen-doped gallium phosphide, and the correlation between its density N T and donor density N D was
It is reported that N T =2.5×10 -20 (N D −N A ) 2 (where N A is the acceptor density). Also this 0.42eV
The density of a deep level with activation energy is 1×
It is reported that the density ranges from 10 12 to 1×10 16 , but the relationship between the density of this level and the luminous efficiency of the light-emitting device has not been studied.
このように窒素原子を添加した燐化ガリウム発
光装置については種々の研究がされている。 Various studies have been conducted on gallium phosphide light-emitting devices to which nitrogen atoms are added.
しかしながら窒素原子を添加した燐化ガリウム
発光素子の発光色は黄緑色か黄色であつて、緑色
ないしは純緑色とは言えないものである。黄緑色
か黄色かは添加した窒素原子の密度によつて決ま
り、その密度の高い程黄色味が増すことが知られ
ている。 However, the emission color of a gallium phosphide light-emitting device doped with nitrogen atoms is yellow-green or yellow, and cannot be said to be green or pure green. Whether it is yellow-green or yellow is determined by the density of added nitrogen atoms, and it is known that the higher the density, the more yellow the color becomes.
従つて所定の発光色を得ようとすると添加可能
な窒素原子の量が制限を受け、鮮明な緑色を発光
し、かつ高い発光効率を有する燐化ガリウム発光
素子を得るのは困難であつた。 Therefore, when trying to obtain a predetermined luminescent color, the amount of nitrogen atoms that can be added is limited, making it difficult to obtain a gallium phosphide light-emitting device that emits clear green light and has high luminous efficiency.
窒素（Ｎ）の添加法としては通常Ga−Ｐ溶液
上にNH3＋H2ガスを流す方法が用いられる。 As a method of adding nitrogen (N), a method of flowing NH 3 +H 2 gas over a Ga-P solution is usually used.
Ga−Ｐ溶液中のＮの濃度が飽和濃度以上にな
るとGaN相が析出しGaPの成長を妨げる。これ
を防ぐためにはNH3濃度を精密に制御し、溶液
中に過飽和を生じないように温度分布、冷却過程
を選ぶ必要があつた。 When the concentration of N in the Ga-P solution exceeds the saturation concentration, a GaN phase precipitates and inhibits the growth of GaP. In order to prevent this, it was necessary to precisely control the NH 3 concentration and choose the temperature distribution and cooling process to avoid supersaturation in the solution.
このような製造方法によつて、製作した従来の
窒素添加燐化ガリウム発光ダイオードは発光ピー
ク波長5680Å（黄色味を帯びた緑色）のもので外
部量子効率は0.05ないし0.15％（例外的には0.7
％）であり、黄色を呈するように多量に窒素を添
加した燐化ガリウム発光ダイオードは発光ピーク
波長5900Åで外部量子効率は例外的に高い場合で
も0.1％であつた。純緑色発光の窒素を添加しな
い燐化ガリウム発光ダイオードは発光ピーク波長
5550Åで外部量子効率0.02ないし、0.04％、例外
的に0.06％であつた。 Conventional nitrogen-doped gallium phosphide light-emitting diodes manufactured using this manufacturing method have an emission peak wavelength of 5680 Å (yellowish green) and an external quantum efficiency of 0.05 to 0.15% (in exceptional cases, 0.7
%), and a gallium phosphide light-emitting diode with a large amount of nitrogen added to give it a yellow color had an emission peak wavelength of 5900 Å and an external quantum efficiency of 0.1%, even if it was exceptionally high. A gallium phosphide light-emitting diode that emits pure green light without adding nitrogen has an emission peak wavelength of
At 5550 Å, the external quantum efficiency was 0.02 to 0.04%, exceptionally 0.06%.
本発明の目的は発光効率の高い、深いエネルギ
準位密度の低いｎ形領域を有する燐化ガリウム発
光装置を提供することである。 An object of the present invention is to provide a gallium phosphide light emitting device having an n-type region with high luminous efficiency and low deep energy level density.
本発明の他の目的は窒素を添加しない高発光効
率の燐化ガリウム発光装置を提供することであ
る。 Another object of the present invention is to provide a gallium phosphide light emitting device with high luminous efficiency without adding nitrogen.
本発明の１実施例によれば、溶液内に一定の温
度差を設け、溶液上に最適範囲内の燐圧を印加
し、一定の温度を保つた溶液の高温部において原
料を溶解すると共に一定温度に保つた溶液の低温
部でエピタキシヤル成長を行なうことによつて得
た１×1013cm-3以下の深いエネルギ準位密度を有
する窒素無添加ｎ形燐化ガリウム領域を含む燐化
ガリウム発光ダイオードが提供される。１×1018
cm-3以下の約0.65eVの深い準位密度を有するｎ形
領域は上記のような方法で初めて得られたもので
あり、他の方法では得ることができなかつたもの
である。本明細書では以下上記の方法を蒸気圧制
御温度差法と呼ぶ。蒸気圧制御温度差法で得た燐
化ガリウム結晶は、欠陥が少なく、組成が正確な
化学量論的組成に近く、成長領域内の特性が均一
に保たれ、発光効率が高い等の特徴を有し、徐冷
液相成長、気相成長で得た燐化ガリウム結晶とは
その性質に明らかな差を有するが、物理的に定義
することには困難があるので本明細書では製造方
法によつて定義する。 According to one embodiment of the present invention, a certain temperature difference is provided in the solution, a phosphorus pressure within an optimal range is applied on the solution, and the raw material is dissolved in the high temperature part of the solution while maintaining a constant temperature. Gallium phosphide containing a nitrogen-free n-type gallium phosphide region with a deep energy level density of 1×10 13 cm -3 or less obtained by epitaxial growth in the low temperature part of a solution kept at a temperature A light emitting diode is provided. 1×10 18
The n-type region having a deep level density of about 0.65 eV below cm -3 was obtained for the first time by the method described above, and could not be obtained by other methods. Hereinafter, the above method will be referred to as a vapor pressure controlled temperature difference method. Gallium phosphide crystals obtained using the vapor pressure controlled temperature difference method have characteristics such as fewer defects, a composition close to the exact stoichiometric composition, uniform properties within the growth region, and high luminous efficiency. The properties of the gallium phosphide crystals obtained by slow cooling liquid phase growth and vapor phase growth are clearly different from each other, but since it is difficult to physically define them, this specification will focus on the manufacturing method. Let's define it accordingly.
１×1013cm-3以下の約0.65eVの深いエネルギ準
位密度を有する窒素無添加ｎ形燐化ガリウム領域
と、このｎ形領域内に十分な量の正孔を注入でき
るアクセプタ密度を有するｐ形領域とを含む燐化
ガリウム発光ダイオードは、極めて高い発光効率
を有する。また視覚的に鮮やかな、ピーク波長
5600Å以下の発光を高発光効率で容易に得られ
る。たとえば窒素を添加しない燐化ガリウム発光
ダイオードで、発光ピーク波長5560Å、外部量子
効率0.14％が得られた。 It has a nitrogen-free n-type gallium phosphide region with a deep energy level density of about 0.65 eV, which is less than 1×10 13 cm -3 , and has an acceptor density that can inject a sufficient amount of holes into this n-type region. A gallium phosphide light emitting diode including a p-type region has extremely high luminous efficiency. Also visually vivid, peak wavelength
Light emission of 5600 Å or less can be easily obtained with high luminous efficiency. For example, a gallium phosphide light-emitting diode without nitrogen added has a peak emission wavelength of 5560 Å and an external quantum efficiency of 0.14%.
燐化ガリウム発光ダイオードのＰ形領域はｎ形
領域に十分な量の正孔を注入できるアクセプタ密
度を有するものであり、好ましくは５×1017cm-3
以上のアクセプタ密度を有する。またｎ形燐化ガ
リウム領域が窒素を含まない場合、Ｐ形領域も窒
素を含まない燐化ガリウム領域である。ことが好
ましい。Ｎ形領域の深いエネルギ準位密度は好ま
しくは７×1012cm-3以下、より好ましくは６×
1012cm-3以下がよい。 The P-type region of the gallium phosphide light-emitting diode has an acceptor density that can inject a sufficient amount of holes into the N-type region, and preferably has an acceptor density of 5×10 17 cm -3
or higher acceptor density. Further, when the n-type gallium phosphide region does not contain nitrogen, the p-type region is also a gallium phosphide region that does not contain nitrogen. It is preferable. The deep energy level density of the N-type region is preferably 7×10 12 cm -3 or less, more preferably 6×
10 12 cm -3 or less is good.
以下、本発明をより詳細に説明する。 The present invention will be explained in more detail below.
良く知られているように、燐化ガリウムの構成
元素である燐原子は蒸気圧の非常に高い元素であ
つて、結晶成長時における高温状態では燐の解離
が生じ、燐化ガリウム結晶中の燐対ガリウムの組
成比が完全に１：１であるところの化学量論的組
成からの偏差が発生し易くなる。この化学量論的
組成からの偏差、即ち非化学量論的組成は必然的
に種々の格子欠陥を生じさせ、発光ダイオードの
発光効率を低下させると考えられる。従来の窒素
を添加しないGaP発光ダイオードの発光効率が低
い原因の１つは、このような非化学量論的組成に
基づく格子欠陥であると考えられる。 As is well known, the phosphorus atom, which is a constituent element of gallium phosphide, has a very high vapor pressure, and at high temperatures during crystal growth, phosphorus dissociates, causing the phosphorus in the gallium phosphide crystal to dissociate. Deviation from the stoichiometric composition in which the composition ratio of gallium to gallium is completely 1:1 tends to occur. It is believed that this deviation from the stoichiometric composition, ie, the non-stoichiometric composition, inevitably causes various lattice defects and reduces the luminous efficiency of the light emitting diode. One of the reasons for the low luminous efficiency of conventional GaP light emitting diodes not added with nitrogen is thought to be lattice defects based on such non-stoichiometric composition.
また、結晶成長中に成長温度が変化すると溶液
中の飽和濃度、成長速度等の成長条件の変化を起
し、やはり格子欠陥を生じる原因となり易い。そ
の結果として結晶の厚さ方向の組成や不純物密度
分布なども変化してしまい本質的に均質な結晶を
得ることが出来ない欠点を有していた。この点で
従来の徐冷法で作成した結晶は本質的な欠点を有
する。 Further, if the growth temperature changes during crystal growth, the growth conditions such as the saturation concentration in the solution and the growth rate change, which is likely to cause lattice defects. As a result, the composition and impurity density distribution in the thickness direction of the crystal change, resulting in the disadvantage that essentially homogeneous crystals cannot be obtained. In this respect, crystals produced by conventional slow cooling methods have an essential drawback.
本発明者の提案した蒸気圧制御温度差法は、結
晶成長時の温度は成長中一定であり、溶液には育
成する結晶の化学量論的組成を最適範囲内に保つ
揮発性構成元素の蒸気圧を印加するものである。
印加蒸気圧の最適、範囲は、育成した結晶の物理
的性質を測定することによつて非常に高い精度で
求められる。燐化ガリウムの場合も、このように
して求めた最適範囲内の燐蒸気圧を印加すると化
学量論的組成からの偏差が最小範囲内に保たれた
非常に良質の結晶を得ることができた。これらの
結晶の電気的光学的性質も非常に秀れており、結
晶内の欠陥が非常に少ないことを裏付けている。
また−化合物半導体は１原子当り平均４個の
価電子を有するものであるが、化学量論的組成か
らの偏差が大きいと族ないし族の原子が過剰
ないし不足となり、種々の欠陥を生じる原因とな
る。これらの欠陥は非発光再結合中心を生じさせ
る原因ともなり、発光素子として好ましくないも
のである。また結晶中に深いエネルギ準位が存在
するとこれらの準位は発光色を変化させたり発光
効率を低下させる原因となる。本発明者は蒸気圧
制御温度差法によつて作成した燐化ガリウム結晶
中に発光効率と密接に関連する伝導帯より約
0.65eVの深い準位を見出し、この深い準位の密
度が結晶成長中の印加燐圧と添加不純物に強く依
存することを解明した。 In the vapor pressure controlled temperature difference method proposed by the present inventor, the temperature during crystal growth is constant during crystal growth, and the solution contains vapor of volatile constituent elements to keep the stoichiometric composition of the growing crystal within the optimum range. It applies pressure.
The optimum range of applied vapor pressure can be determined with great precision by measuring the physical properties of the grown crystal. In the case of gallium phosphide, by applying a phosphorus vapor pressure within the optimal range determined in this way, it was possible to obtain very high quality crystals with deviations from the stoichiometric composition kept within the minimum range. . The electro-optical properties of these crystals are also excellent, supporting the fact that there are very few defects within the crystals.
Compound semiconductors have an average of four valence electrons per atom, but if there is a large deviation from the stoichiometric composition, there will be an excess or deficiency of group or group atoms, which can cause various defects. Become. These defects also cause the generation of non-radiative recombination centers, which is undesirable as a light emitting device. Furthermore, if deep energy levels exist in the crystal, these levels cause changes in the color of the emitted light and decrease in luminous efficiency. The present inventor discovered that the conduction band, which is closely related to the luminous efficiency, in the gallium phosphide crystal prepared by the vapor pressure controlled temperature difference method
We discovered a deep level of 0.65 eV and found that the density of this deep level strongly depends on the phosphorus pressure applied during crystal growth and the added impurities.
すなわち蒸気圧制御温度差法を用いて化学量論
的組成からの偏差を最小範囲内に止めつつ、ドナ
不純物の密度を減少させるときわめて発光効率の
高いｎ形燐化ガリウム領域を含む燐化ガリウム発
光装置が得られ、そのｎ形領域内において約
0.65eVの深い準位の密度はきわめて低かつた。 In other words, if the density of donor impurities is reduced while keeping the deviation from the stoichiometric composition within a minimum range using the vapor pressure controlled temperature difference method, gallium phosphide containing an n-type gallium phosphide region with extremely high luminous efficiency can be obtained. A light emitting device is obtained in which within its n-type region about
The density of the deep level of 0.65 eV was extremely low.
また燐化ガリウム発光ダイオードからの発光色
を黄色味がかつたものにしてしまうところの窒素
原子の添加を行うことなく、即ち浅い準位を形成
するドナあるいはアクセプタ以外の不純物は全く
添加せずに純緑色の発光色でしかも、高効率の燐
化ガリウム発光ダイオードが実現された。この理
由として考えられる最大のものは、結晶成長中の
不純物密度が変化せず成長方向で一定に分布し、
ｎ層からｐ層への遷移層もステツプ状に変化する
ためと考えることができる。 In addition, there is no need to add nitrogen atoms, which would make the color of light emitted from a gallium phosphide light-emitting diode yellowish, or in other words, no impurities other than donors or acceptors that form shallow levels are added. A highly efficient gallium phosphide light-emitting diode that emits pure green light has been realized. The biggest possible reason for this is that the impurity density during crystal growth does not change and is uniformly distributed in the growth direction.
This can be considered to be because the transition layer from the n-layer to the p-layer also changes in a step-like manner.
第１図に燐化ガリウム発光ダイオードのｎ形領
域のドナー密度を変化させた時の輝度の変化の様
子を示す。縦軸は輝度をリニア目盛で、横軸はド
ナ密度を対数目盛で示す。試料はすべて蒸気圧制
御温度差法を用いて、窒素を添加せずに、燐化ガ
リウム基板上にＰ形層、ｎ形層をエピタキシヤル
成長させた発光ダイオードである。ドナー密度の
減少と共に輝度の増加することが明らかである。
１×1016cm-3以下のドナの密度では輝度が非常に
高くなつており、６×1015cm-3以下、より好まし
くは３×1015cm-3以下で輝度が極めて高くなつて
いることがわかる。 FIG. 1 shows how the brightness changes when the donor density of the n-type region of a gallium phosphide light-emitting diode is changed. The vertical axis shows the brightness on a linear scale, and the horizontal axis shows the donor density on a logarithmic scale. All the samples were light emitting diodes in which a P-type layer and an N-type layer were epitaxially grown on a gallium phosphide substrate using a vapor pressure controlled temperature difference method without adding nitrogen. It is clear that the brightness increases with decreasing donor density.
The brightness is extremely high at a donor density of 1×10 16 cm -3 or less, and extremely high at a donor density of 6×10 15 cm -3 or less, more preferably 3×10 15 cm -3 or less. I understand that.
Ｐ形領域のアクセプタ密度はｎ形領域のドナ密
度ほどは輝度に影響せず、ｎ形領域に十分な量の
正孔を注入できるものであればよいが、より好ま
しくは５×1017cm-3以上がよいことも判明した。
但し、ｎ形領域のドナ密度が低い場合、ｎ形領域
からＰ形領域に注入される電子の量は少なくなる
ので、所望の電流を流すにはＰ形領域のアクセプ
タ密度を十分高くすることが望ましい。たとえば
ｎ形領域のドナ密度が約６×1015cm-3以下の場
合、Ｐ形領域のアクセプタ密度は約１×1018cm-3
以上が好ましい。 The acceptor density of the P-type region does not affect the brightness as much as the donor density of the n-type region, and it is sufficient that it can inject a sufficient amount of holes into the n-type region, but it is more preferably 5×10 17 cm - It was also found that 3 or more is good.
However, if the donor density in the n-type region is low, the amount of electrons injected from the n-type region to the p-type region will be small, so it is necessary to make the acceptor density in the p-type region sufficiently high to flow the desired current. desirable. For example, if the donor density in the n-type region is about 6×10 15 cm -3 or less, the acceptor density in the p-type region is about 1×10 18 cm -3
The above is preferable.
なお、結晶成長時に印加する燐蒸気圧を最適範
囲から外したり、成長温度を結晶成長中に変動さ
せたりすると得られる発光ダイオードの輝度は第
１図の値を大きく下回る。この結果より、燐化ガ
リウム発光ダイオードの少なくとも活性層は化学
量論的組成からの偏差の小さい、かつ欠陥の少な
い結晶であることが望ましく、この効果が一定の
不純物密度分布を実現することを可能ならしめ
た。この様な高効率かつ純緑色光発光を実現する
ためには、蒸気圧制御温度差法を極力有効に利用
することしか手段がなく種々の実験を繰り返し行
なつた結果として以下の構造のデバイス製作を行
なわなければ本願発明の燐化ガリウム発光装置を
実現できないことが明らかにされた。ことがわか
る。これらを定量的に定義することは現在の測定
精度では困難であるが、例示的に表現すれば結晶
成長中の印加蒸気圧は最適値を中心にほぼ±50％
の範囲内、成長温度は成長中を通じて約５℃以
内、かつ微小であつでも急激な温度変化はなるべ
く抑える（約２℃／分以下）ことが好ましい。よ
り好ましくは蒸気圧は最適値を中心に±５％以
内、成長温度変化はほぼ±２℃以内、とすること
が望ましい。 Note that if the phosphorus vapor pressure applied during crystal growth is outside the optimum range or the growth temperature is varied during crystal growth, the luminance of the light emitting diode obtained will be much lower than the value shown in FIG. 1. From this result, it is desirable that at least the active layer of a gallium phosphide light-emitting diode is a crystal with small deviation from the stoichiometric composition and few defects, and this effect makes it possible to realize a constant impurity density distribution. I got used to it. In order to achieve such high efficiency and pure green light emission, the only way is to utilize the vapor pressure controlled temperature difference method as effectively as possible, and as a result of repeated various experiments, we fabricated a device with the following structure. It has been revealed that the gallium phosphide light emitting device of the present invention cannot be realized unless the above steps are carried out. I understand that. It is difficult to define these quantitatively with current measurement accuracy, but to express it illustratively, the applied vapor pressure during crystal growth is approximately ±50% around the optimum value.
It is preferable that the growth temperature be within the range of about 5° C. throughout the growth, and that even small but rapid temperature changes should be suppressed as much as possible (about 2° C./min or less). More preferably, the vapor pressure is within ±5% around the optimum value, and the growth temperature change is preferably within ±2°C.
このように蒸気圧制御温度差法を用いることに
より、非発光中心となる欠陥を減少させることが
でき、非常に低い深い準位密度が実現でき、高い
発光効率が得られたのであると考えられる。 It is thought that by using the vapor pressure controlled temperature difference method in this way, it was possible to reduce the number of defects that serve as non-luminescent centers, resulting in an extremely low deep level density and high luminous efficiency. .
次に第２図に概略的に示す液相エピタキシヤル
成長装置を参照して本発明の燐化ガリウム発光ダ
イオードの製造方法の例を説明する。 Next, an example of the method for manufacturing a gallium phosphide light emitting diode of the present invention will be described with reference to a liquid phase epitaxial growth apparatus schematically shown in FIG.
第２図において、本体ないしボート１は溶液溜
２，３を含み、溶液溜２，３の下部に接しつつ摺
動可能なスライド部材６を通すための通路を有す
る。溶液溜２，３の内部にはそれぞれｎ形エピタ
キシヤル成長を行なうための溶液４、Ｐ形エピタ
キシヤル成長を行なうための溶液５を収容する。
溶液溜２，３の上部は半気密に封じられ連結細管
８を介して燐蒸気圧源７に通じている。燐蒸発源
７の温度を制御することによつて所望の燐蒸気圧
を溶液溜に供給することができる。もちろん連結
細管、燐蒸発源を各溶液溜に別個に設けてもよ
い。スライド部材６は単結晶基抜１０を収容する
ための凹部を有する。１つの凹部のみを図示した
が、複数個の凹部を設け、複数個の単結晶基板を
収容し、それらの上に成長条件を変化させずにつ
ぎつぎとエピタキシヤル成長を行なうことができ
る。これは成長温度を一定に保つ蒸気圧制御温度
差法の利点の１つである。 In FIG. 2, the main body or boat 1 includes solution reservoirs 2 and 3, and has a passage through which a sliding member 6 is slidable while contacting the lower portions of the solution reservoirs 2 and 3. Solution reservoirs 2 and 3 contain a solution 4 for performing n-type epitaxial growth and a solution 5 for performing p-type epitaxial growth, respectively.
The upper portions of the solution reservoirs 2 and 3 are semi-hermetically sealed and communicated with a phosphorus vapor pressure source 7 via a connecting capillary 8. By controlling the temperature of the phosphorus evaporation source 7, a desired phosphorus vapor pressure can be supplied to the solution reservoir. Of course, a connecting capillary and a phosphorus evaporation source may be provided separately for each solution reservoir. The slide member 6 has a recess for accommodating the single crystal punch 10. Although only one recess is illustrated, a plurality of recesses can be provided to accommodate a plurality of single crystal substrates, and epitaxial growth can be performed on them one after another without changing the growth conditions. This is one of the advantages of the vapor pressure controlled temperature difference method that keeps the growth temperature constant.
溶液4.5としてGa中にGaP多結晶を浮遊させ、
ドナ不純物としてTe、アクセプタ不純物として
はZnを用い、結晶成長温度900℃、印加燐蒸気圧
は設定値±５％でｎ層、Ｐ層の連続エピタキシヤ
ル成長を行なつた。また非常に低いドナー密度の
ｎ形領域はドナ不純物を用いることなく、原料と
して多結晶GaPのみを用いて成長することができ
た。 GaP polycrystals are suspended in Ga as solution 4.5,
Using Te as the donor impurity and Zn as the acceptor impurity, successive epitaxial growth of the n layer and the p layer was performed at a crystal growth temperature of 900° C. and an applied phosphorus vapor pressure of ±5% of the set value. In addition, an n-type region with a very low donor density could be grown using only polycrystalline GaP as a raw material without using donor impurities.
なお投入すべき多結晶GaPの量は結晶成長中
Ga溶液のGaP濃度を飽和溶解度に保つ量以上で
あることが必要である。 The amount of polycrystalline GaP that should be added depends on the amount of polycrystalline GaP that should be added during crystal growth.
It is necessary that the GaP concentration in the Ga solution be equal to or higher than the amount that keeps the GaP concentration at saturation solubility.
印加すべき燐蒸気圧は成長温度に移存し、約
50Torrから約200Torrの範囲である。たとえば
成長温度が900℃の時約150Torr近く、800℃の時
約67Tor近くである。 The phosphorus vapor pressure to be applied shifts to the growth temperature and is approximately
It ranges from 50 Torr to about 200 Torr. For example, when the growth temperature is 900℃, it is about 150 Torr, and when the growth temperature is 800℃, it is about 67 Torr.
次にP+n接合のｎ側の浅いエネルギ準位を形成
するドナ密度の減少が高輝度化をもたらす原因を
検討した結果を述べる。 Next, we will discuss the results of examining the reason why the decrease in the donor density, which forms the shallow energy level on the n side of the P + n junction, brings about higher brightness.
第３図は深いエネルギ準位密度と浅いエネルギ
準位を有するドナ密度との関係を示したものであ
る。なお測定には深いエネルギ準位を形成する、
再結合中心等を極めて低密度まで測定可能な光容
量法を用いた。深いエネルギ準位の活性化、エネ
ルギは伝導帯より約0.65eVであり、その密度は
ドナ密度の減少とともに減少している。 FIG. 3 shows the relationship between deep energy level density and donor density having shallow energy levels. In addition, for measurement, a deep energy level is formed.
We used a photocapacitance method that can measure recombination centers down to extremely low densities. Activation of the deep energy level, the energy is about 0.65 eV below the conduction band, and its density decreases with decreasing donor density.
ND１×1016cm-3の範囲内で、測定値は必ずし
も直線の延長周辺上にはなく1013cm-3以下の斜線
部内に存在するが深いエネルギ準位密度はND＞
１×1016cm-3の範囲内のものより明らかに減少し
ている。不純物を添加することなく結晶成長を行
つたｎ形領域の場合、たとえばドナ密度は約２×
1015cm-3であり、そのとき上記深い準位密度は約
５×1012cm-3と極めて低い値を示した。 Within the range of N D 1×10 16 cm -3 , the measured values are not necessarily on the extended periphery of the straight line, but within the shaded area below 10 13 cm -3 , but the deep energy level density is N D >
This is clearly lower than that in the range of 1×10 16 cm -3 . In the case of an n-type region grown without adding impurities, the donor density is, for example, approximately 2×
10 15 cm -3 , and at that time, the deep level density showed an extremely low value of about 5×10 12 cm -3 .
結晶成長の条件を十分制御すれば測定値を図面
中破線で示した約７×1012cm-3以下の斜線部内に
収めることも容易である。 If the crystal growth conditions are sufficiently controlled, it is easy to keep the measured values within the shaded area of approximately 7×10 12 cm −3 or less shown by the broken line in the drawing.
なお印加する燐圧を零にしたり10倍にする等最
適範囲から大きく外すと深い準位の密度は大きく
増大する。緑色発光ダイオードにおいては現在の
ところ、その発光効率は、数％以下であつて、順
方向電圧印加によつて注入された少数キヤリアの
ほとんどすべては、非発光再結合によつて失われ
てしまうと考えられる。従つて上記発光ダイオー
ドの発光を決定的に支配しているのは、上記非発
光再結合をもたらす再結合中心の密度であると言
える。深い低エネルギ準位は、この非発光再結合
中心の形成に寄与すると考えられるので、高い発
光効率を得るためには深いエネルギ準位を出来る
だけ減少させるのが効果的であると考えられる。 Note that if the applied phosphorus pressure is significantly removed from the optimal range, such as by reducing it to zero or increasing it by a factor of 10, the density of deep levels increases significantly. Currently, the luminous efficiency of green light emitting diodes is below a few percent, and almost all of the minority carriers injected by applying a forward voltage are lost through non-radiative recombination. Conceivable. Therefore, it can be said that what decisively controls the light emission of the light emitting diode is the density of recombination centers that bring about the non-radiative recombination. It is believed that deep low energy levels contribute to the formation of this non-radiative recombination center, so it is considered effective to reduce the deep energy levels as much as possible in order to obtain high luminous efficiency.
第４図は、上記深い準位密度と発光輝度の関係
を示したものである。縦軸は発光輝度（Ft−Ｌ）
を対数目盛で、横軸は深い準位密度cm-3）を対数
目盛で示す。 FIG. 4 shows the relationship between the deep level density and luminance. The vertical axis is luminance (Ft-L)
is shown on a logarithmic scale, and the horizontal axis shows the deep level density (cm -3 ) on a logarithmic scale.
第４図に示されているように前記深い準位密度
の減少に従い、発光輝度がほぼ前記深い準位密度
の逆数に比例して増大していることは、この深い
準位が前述したところの非発光もしくは赤外光の
再結合中心として支配的な準位となつていること
を証明していると言える。従つて深いエネルギ準
位密度を１×1013cm-3以下、好ましくは７×1012
cm-3以下、より好ましくは６×1012cm-3以下にす
ることは、高輝度の燐化ガリウム発光ダイオード
を得るのに非常に有効であることが判る。本発明
は深い準位の密度を減少させ、それによつて高輝
度を得るものである。 As shown in FIG. 4, as the deep level density decreases, the luminance increases approximately in proportion to the reciprocal of the deep level density. This can be said to prove that it is a dominant level as a recombination center for non-emissive or infrared light. Therefore, the deep energy level density should be 1×10 13 cm -3 or less, preferably 7×10 12
It turns out that setting the density to below cm -3 , more preferably below 6×10 12 cm -3 is very effective in obtaining a high-luminance gallium phosphide light-emitting diode. The present invention reduces the density of deep levels, thereby obtaining high brightness.
再結合中心として支配的な準位の減少は、当
然、注入された少数キヤリアの寿命を長くさせる
ことになり、このことは、注入された少数キヤリ
アがより有効に発光再結合することを可能にす
る。 Decreasing the level that is dominant as a recombination center naturally lengthens the lifetime of the injected minority carriers, which allows the injected minority carriers to more effectively recombine radiatively. do.
第５図に燐化ガリウム発光ダイオードの輝度と
ｎ形領域内の正孔の寿命との関係を示す。縦軸は
輝度（mcd）を対数目盛で、横軸は寿命（sec）
を対数目盛で示す。寿命が長くなると共に輝度が
増大していることが明らかである。このことも本
発明の効果を証明していると言える。 FIG. 5 shows the relationship between the brightness of a gallium phosphide light emitting diode and the lifetime of holes in the n-type region. The vertical axis is luminance (mcd) on a logarithmic scale, and the horizontal axis is life (sec)
is shown on a logarithmic scale. It is clear that the brightness increases as the lifetime increases. This can also be said to prove the effect of the present invention.
以上説明したように、本発明によれば高輝度な
いしは高発光効率の燐化ガリウム発光ダイオード
が得られる。さらに人間の視覚上鮮やかな緑色に
映ずる5600Å以下のピーク波長の発光が窒素を添
加することなく容易に得られる。 As explained above, according to the present invention, a gallium phosphide light emitting diode with high brightness or high luminous efficiency can be obtained. Furthermore, light emission with a peak wavelength of 5,600 Å or less, which appears as a bright green color to the human eye, can be easily obtained without adding nitrogen.
なお本発明を限られた実施例に沿つて説明した
が、実施例は何ら制限的な意味を持たず、さまざ
まな変形、応用、組合わせ改良などができること
は自明であろう。 Although the present invention has been described with reference to limited examples, it is obvious that the examples do not have any limiting meaning and that various modifications, applications, combinations and improvements can be made.
第１図は、本発明の実施例によるｎ形GaP層の
ドナ密度と発光ダイオードからの輝度との関係を
示した特性曲線図、第２図は本発明に用いた蒸気
圧制御温度差法による液相エピタキシヤル成長装
置の模式図、第３図は深い準位の（トラツプ）密
度と浅い準位のドナ密度との関係を示すグラフ、
第４図は本発明の効果を説明する輝度と深い準位
の密度との関係を示すグラフ、第５図は輝度と寿
命との関係を示すグラフである。
FIG. 1 is a characteristic curve diagram showing the relationship between the donor density of the n-type GaP layer and the brightness from the light emitting diode according to an embodiment of the present invention, and FIG. A schematic diagram of a liquid phase epitaxial growth apparatus, and FIG. 3 is a graph showing the relationship between deep level (trap) density and shallow level donor density.
FIG. 4 is a graph showing the relationship between brightness and deep level density to explain the effects of the present invention, and FIG. 5 is a graph showing the relationship between brightness and lifetime.
Claims (1)
厚さ方向で一定かつ１×1016cm-3以下の実効的ド
ナー密度及び１×1013cm-3以下の伝導帯からほぼ
0.65eVの活性化エネルギーを持つ準位の密度を
有するｎ形GaP層が設けられ、更にその上に窒素
無添加で不純物密度が厚さ方向で一定かつ５×
1017cm-3以上の実効的アクセプター密度を有する
ｐ形GaP層が設けられ、前記ｎ形GaP層と前記ｐ
形GaP層間で不純物密度分布が階段状に変化する
構造を有していることを特徴とする燐化ガリウム
発光装置。1 On an n-type GaP substrate without nitrogen addition, the impurity density is constant in the thickness direction, and the effective donor density is less than 1×10 16 cm -3 and the conduction band is less than 1×10 13 cm -3 .
An n-type GaP layer having a level density with an activation energy of 0.65 eV is provided, and furthermore, an n-type GaP layer with no nitrogen added and an impurity density constant in the thickness direction and 5×
A p-type GaP layer having an effective acceptor density of 10 17 cm -3 or more is provided, and the n-type GaP layer and the p-type GaP layer are
A gallium phosphide light-emitting device characterized by having a structure in which impurity density distribution changes stepwise between GaP layers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10938979A JPS5632780A (en) | 1979-08-27 | 1979-08-27 | Gallium phosphide light emitting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10938979A JPS5632780A (en) | 1979-08-27 | 1979-08-27 | Gallium phosphide light emitting device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5632780A JPS5632780A (en) | 1981-04-02 |
| JPS6358383B2 true JPS6358383B2 (en) | 1988-11-15 |
Family
ID=14508988
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10938979A Granted JPS5632780A (en) | 1979-08-27 | 1979-08-27 | Gallium phosphide light emitting device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5632780A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2643396B2 (en) * | 1988-12-15 | 1997-08-20 | 日立電線株式会社 | Plate-shaped lead wire soldered to a ceramic capacitor |
-
1979
- 1979-08-27 JP JP10938979A patent/JPS5632780A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5632780A (en) | 1981-04-02 |
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