JP2005019902A - Semiconductor light emitting element using zener tunneling effect - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem; it is difficult to manufacture a semiconductor light emitting element which emits light between a conduction band and a valence band when a p-type or n-type semiconductor is difficult to manufacture in a conventional semiconductor light emitting element which is constituted of junction between a p-type semiconductor and an n-type semiconductor. <P>SOLUTION: In the element, two electrode layers are both constituted of an n-type semiconductor or a p-type semiconductor and light is emitted by injecting a hole (when an electrode is constituted of an n-type semiconductor) or an electron (when an electrode is constituted of a p-type semiconductor) inside an active layer by Zener tunneling effect. A semiconductor light emitting element can be realized in a semiconductor material wherein p-type or n-type doping cannot be realized and an inexpensive and compact semiconductor light source can be supplied in various wavelength regions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１０】
また、表２に、ＩｎＡｓ／ＡｌＳｂ超格子構造を３５回繰り返した発光領域の構造を示す。
【００１１】
【表２】

【００１２】
実施例２
表３に、ＩｎＡｓをベースにした半導体レーザーの図１の▲１▼〜▲３▼に対応する各層の膜厚を示す。
【００１３】
【表３】

【００１４】
上部及び下部電極層である５×１０^１８ｃｍ^−３にドーピングされたＩｎＡｓ層は発生した光を閉じ込めるクラッド領域の役目をする。また、発光領域であるＩｎＡｓ／ＡｌＳｂ超格子構造を挟む２つのＩｎＡｓ層（厚さが３μｍ、ドーピング濃度が３×１０^１６ｃｍ^−３）はクラッド領域における自由キャリア吸収を減少させるためにコア領域として挿入されている。ＩｎＡｓ／ＡｌＳｂ超格子構造は表２に示す構造を３５回繰り返した構造から構成される。
【００１５】
この素子構造は分子線エピタキシー法によりｎ型ＩｎＡｓ（１００）基板上にＡｓバルブドクラッカー砒素セル、及びＳｂクラッカーセルがついた分子線エピタキシー装置により作製した。成長中の基板温度は４１０℃で、量子カスケード構造成長時には成長速度をＩｎＡｓでは０．２原子層毎秒、ＡｌＳｂでは０．４原子層毎秒とした。
【００１６】
成長後、幅３０ミクロンのリッジ構造をウエットエッチング及びフォトリソグラフィーで作製した。パッシベーション膜としてＳｉＯ_２を用いた。コンタクトをとるためにストライプ上のＳｉＯ_２をエッチングで除去し、その上にＣｒ／Ａｕ電極を蒸着した。また、ＩｎＡｓ基板の裏側を薄く研磨し、Ｃｒ／Ａｕを蒸着して下部電極を形成した。リッジレーザー構造の共振器長は０．５ｍｍから１．５ｍｍである。
【００１７】
図３に、作製した発光素子の測定温度４Ｋにおける発光スペクトルの注入電流依存性を示す。リッジ構造のストライプの長さはおよそ１ｍｍである。エミッション測定はステップスキャンフーリエ赤外分光器を用いて行い、素子には５ＫＨｚでデューティ比０．０５％の電流パルス電流を印加した。
【００１８】
注入電流が１．８Ａ以下では、ＩｎＡｓ／ＡｌＳｂ超格子構造のサブバンド間発光（エネルギー１６０ｍｅＶ）が主に観測されるが、注入電流を増大させ、１．９Ａ以上になると４１０ｍｅＶ付近のＩｎＡｓのバンド間発光が観測されるようになる。これは１．９Ａ以上の注入電流では、高電界がかかりツェナートンネル効果が起こっていることを意味する。さらに電流を増大してゆくと、ＩｎＡｓ／ＡｌＳｂ超格子のサブバンド間発光は減少して消滅し、ツェナートンネル効果によるＩｎＡｓのバンド間発光が主となり、注入電流が３Ａ以上になると、レーザー発振に至る。
【００１９】
【発明の効果】
これまで、ｐ型又はｎ型ドーピングが実現できなかった半導体材料において半導体発光素子が実現でき、さまざまな波長領域において安価でコンパクトな半導体光源を供給できる。
【図面の簡単な説明】
【図１】図１は、ｎ−ｉ−ｎ構造の発光素子の概念図である。
【図２】図２は、ｐ−ｉ−ｐ構造の発光素子の概念図である。
【図３】図３は、実施例２により作成した半導体レーザーの発光スペクトル及び発振スペクトルである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor light emitting device such as a semiconductor light emitting diode or a semiconductor laser using a Zener tunnel effect.
[0002]
[Prior art]
Light-emitting elements such as light-emitting diodes and lasers using semiconductors are composed of pn junctions and use a phenomenon in which electrons and holes are combined in the active layer and the relaxation energy is released as photons. Both p-type and n-type In general, it is formed of a material that can obtain the conductivity type.
[0003]
[Problems to be solved by the invention]
Conventional semiconductor light emitting devices are mainly composed of a junction of a p-type semiconductor and an n-type semiconductor, but emit light between a conduction band and a valence band when it is difficult to produce a p-type or n-type semiconductor. It is difficult to manufacture a semiconductor light emitting device.
[0004]
[Means for Solving the Problems]
A semiconductor light emitting device that emits light between bands by generating electrons or holes by using a Zener tunnel effect (interband tunnel effect) without using an n-type semiconductor or a p-type semiconductor and injecting them into an active region was produced.
[0005]
In the present invention, the two electrode layers are both composed of an n-type semiconductor or a p-type semiconductor, and holes are formed in the active layer by the Zener tunnel effect (interband tunnel effect) (when the electrode is composed of an n-type semiconductor). Alternatively, the present invention relates to an element that emits light by injecting electrons (when an electrode is formed of p-type).
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a concept of a light-emitting element having an nin structure according to the present invention. The n layers of (1) and (3) are n-type doped with electrode layers. The i layer of (2) is composed of a superlattice structure, and the superlattice structure of the i layer blocks the flow of electrons until an electric field that causes a Zener tunnel effect is applied. When a high electric field is applied, holes are generated in the depletion layer near the i layer and the electrode layer by the Zener tunnel, and light is emitted by recombining with electrons in the active region.
[0007]
Similarly, FIG. 2 shows the concept of a light emitting device having a pip structure according to the present invention. The p layers of (4) and (6) are doped p-type in the electrode layer. The i layer of (5) is composed of a superlattice structure in the same manner as the light emitting element of the n-i-n structure, and the i-layer superlattice structure flows holes until an electric field that causes a Zener tunnel effect is applied. Block. When a high electric field is applied, electrons are generated in the depletion layer near the i layer and the electrode layer by the Zener tunnel, and light is emitted by recombination with holes in the active region.
[0008]
【Example】
Example 1
Table 1 shows the film thickness of each layer corresponding to (1) to (3) in FIG. 1 of the light-emitting diode based on InAs. The upper and lower electrode layers are composed of InAs layers doped to 5 × 10 ¹⁸ cm ⁻³ .
[0009]
[Table 1]

[0010]
Table 2 shows the structure of the light emitting region in which the InAs / AlSb superlattice structure is repeated 35 times.
[0011]
[Table 2]

[0012]
Example 2
Table 3 shows the film thickness of each layer corresponding to (1) to (3) in FIG. 1 of the semiconductor laser based on InAs.
[0013]
[Table 3]

[0014]
The InAs layer doped to 5 × 10 ¹⁸ cm ⁻³ as the upper and lower electrode layers serves as a cladding region for confining the generated light. In addition, two InAs layers (thickness: 3 μm, doping concentration: 3 × 10 ¹⁶ cm ⁻³ ) sandwiching the InAs / AlSb superlattice structure, which is a light emitting region, serve as a core region in order to reduce free carrier absorption in the cladding region. Has been inserted. The InAs / AlSb superlattice structure is formed by repeating the structure shown in Table 2 35 times.
[0015]
This device structure was fabricated by a molecular beam epitaxy apparatus in which an As valved cracker arsenic cell and an Sb cracker cell were provided on an n-type InAs (100) substrate by a molecular beam epitaxy method. The substrate temperature during growth was 410 ° C., and the growth rate was set to 0.2 atomic layer per second for InAs and 0.4 atomic layer per second for AlSb during quantum cascade structure growth.
[0016]
After the growth, a ridge structure having a width of 30 microns was produced by wet etching and photolithography. SiO ₂ was used as a passivation film. In order to make a contact, SiO ₂ on the stripe was removed by etching, and a Cr / Au electrode was deposited thereon. Further, the back side of the InAs substrate was thinly polished, and Cr / Au was deposited to form a lower electrode. The resonator length of the ridge laser structure is 0.5 mm to 1.5 mm.
[0017]
FIG. 3 shows the injection current dependence of the emission spectrum of the manufactured light-emitting element at a measurement temperature of 4K. The length of the ridge structure stripe is about 1 mm. Emission measurement was performed using a step-scan Fourier infrared spectrometer, and a current pulse current with a duty ratio of 0.05% was applied to the element at 5 KHz.
[0018]
When the injection current is 1.8 A or less, the intersubband emission (energy 160 meV) of the InAs / AlSb superlattice structure is mainly observed. However, when the injection current is increased to 1.9 A or more, the InAs band near 410 meV is observed. Light emission is observed. This means that at an injection current of 1.9 A or more, a high electric field is applied and the Zener tunnel effect occurs. When the current is further increased, the light emission between the subbands of the InAs / AlSb superlattice decreases and disappears, and the light emission between the InAs bands due to the Zener tunnel effect becomes the main. When the injection current becomes 3 A or more, laser oscillation occurs. It reaches.
[0019]
【The invention's effect】
A semiconductor light emitting device can be realized in a semiconductor material that has not been realized with p-type or n-type doping so far, and an inexpensive and compact semiconductor light source can be supplied in various wavelength regions.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a light-emitting element having an nin structure.
FIG. 2 is a conceptual diagram of a light-emitting element having a pip structure.
FIG. 3 shows an emission spectrum and an oscillation spectrum of a semiconductor laser produced according to Example 2.

Claims (1)

A semiconductor light-emitting element that is composed of only an n-type or p-type semiconductor and emits light between bands by injecting carriers by the Zener tunnel effect.

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