JPS63288086A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enable stable oscillation only at a fundamental transverse mode and the control of the oscillation by bringing the width of a rib-shaped optical guide in an index waveguide structure section and the thickness of a clad layer left between an active layer and said ZnSe layer within a specific range value. CONSTITUTION:Structure consisting of an N-type GaAs buffer layer 202, an N-type AlxGa1-xAs first clad layer 203, an AlyGa1-yAs active layer x>y, 204, a P-type AlzGa1-zAs second clad layer z>y, 205 and a P-type GaAs contact layer 206 is formed continuously onto an N-type GaAs substrate 201. A mask 207 for etching a rib is shaped. The P-type GaAs contact layer 206 and one part of the P-type AlzGa1-zAs second clad layer are removed through etching. A ZnSe buried layer 209 as a II-VI compound semiconductor is grown. The ZnSe buried layer 209 is gotten rid of to a striped shape through etching. A P side electrode 210 and an N side electrode 211 are formed. It is proper that the width of an index waveguide extends over 0.5-10mum and residual film thickness after the second clad layer is etched over 0-2.0mum.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、半４体レーザの構造に関するものである。[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of a half-four body laser.

〔従来の技術〕[Conventional technology]

半導体レーザ（以下ＬＤと記す、）を光情報処理用装置
等の光源として使用する際、出射光の一部が外部光学系
等により反射され再度ＬＤの共振器に戻ることにより、
干渉効果によってＬＤからの出力光の雑音成分（以下戻
り光雑音と記す、）が増大し、実用に供することが不可
能となる場合がある、この戻り光雑音を低減させる手段
として縦モードを多軸発振させる方法がある。これを実
現する方法として、少なくとも一方の共振器端面近傍で
屈折率４波路輻と電流注入幅をほぼ同程度として屈折率
導波構造とし、該共振器中央付近で屈折率導波路幅を電
流注入幅より充分広くし利得導波構造としかつ光出射側
の屈折率導波領域長が１０乃至５００μｍ１モニタ側の
屈折率導波領域が５００μｍ以下、利得導波領域長が１
０乃至５００μｍＳ屈折率導波領域幅がｌ乃至ｌＯμｍ
１利得導波領域幅が５μｍ以上、電流注入幅が１乃至１
０μｍであるリブ状の光導波路を存し、かつ該光導波路
側面を■−■族化族化合物半回体層め込んだ構造の半導
体レーザがあった。When a semiconductor laser (hereinafter referred to as LD) is used as a light source for an optical information processing device, a portion of the emitted light is reflected by an external optical system and returns to the resonator of the LD.
Due to the interference effect, the noise component of the output light from the LD (hereinafter referred to as return light noise) may increase, making it impossible to put it into practical use.As a means to reduce this return light noise, we have developed multiple longitudinal modes. There is a way to generate axial oscillation. To achieve this, a refractive index waveguide structure is created in which the refractive index waveguide width and the current injection width are approximately the same near at least one end face of the resonator, and the refractive index waveguide width is changed to the current injection width near the center of the resonator. The gain waveguide structure is sufficiently wider than the width, and the refractive index waveguide region length on the light output side is 10 to 500 μm1.The refractive index waveguide region on the monitor side is 500 μm or less, and the gain waveguide region length is 1
0 to 500μmS refractive index waveguide region width l to lOμm
1 gain waveguide region width is 5 μm or more, current injection width is 1 to 1
There is a semiconductor laser having a structure including a rib-shaped optical waveguide having a thickness of 0 μm, and a semicircular layer of a compound of the ■-■ group embedded in the side surface of the optical waveguide.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

しかし前述の従来技術では活性領域の幅Ｗと、■−■−
■合物半導体層直下のクラッド層の層厚ｔの大きさの最
適値が示されておらず、Ｗ及びｔが大きくなりすぎると
、横モードに高次モードの光の発振が起こり、光情報記
！ｉ　ＨＩの書き込みや読み出しのための微小スポット
を得られないという問題点を有していた。またあまりに
Ｗが小さいと製造の方法が難しく、安価に大量に半導体
レーザを供給できないという問題点を任していた。However, in the prior art described above, the width W of the active region and ■−■−
■The optimum value for the layer thickness t of the cladding layer directly under the compound semiconductor layer has not been shown, and if W and t become too large, oscillation of light in a higher order mode will occur in the transverse mode, resulting in optical information. Record! There was a problem in that it was not possible to obtain a minute spot for writing and reading iHI. Furthermore, if W is too small, the manufacturing method is difficult, resulting in the problem that semiconductor lasers cannot be supplied in large quantities at low cost.

そこで本発明はこのような問題点を解決するもので、そ
の目的とするところは縦多モード発振を保ちつつ発振領
域以外への電流の漏洩を完全に遮断し、しかも育効な光
閉じ込め効果により、基本横モードのみの発振を制御可
能とし、１ｔｈが低く、高出力まで安定して発振可能な
半導体レーザを提供するところにある。The present invention is intended to solve these problems, and its purpose is to completely block current leakage to areas other than the oscillation region while maintaining vertical multi-mode oscillation, and to achieve effective optical confinement. The object of the present invention is to provide a semiconductor laser that can control oscillation in only the fundamental transverse mode, has a low 1th, and can oscillate stably up to high output.

〔問題点を解決するための手段〕[Means for solving problems]

本発明の半導体レーザは、Ａρｘ　Ｇ　ａ　１−　ｚ　
Ａｓ（０≦ｘ＜１）化合物半導体より成る活性層及びク
ラブト層から構成されるダブルへテロ接合型半導体レー
ザの該活性層直上の該クラッド層の１部をエツチング除
去して成り、かつ少なくとも一方の共振器ｒＪ面近傍で
屈折率導波路幅と電流注入幅をほぼ同程度として屈折率
導波構造とし、該屈折率導波構造以外の領域では屈折率
導波路幅を電流注入幅より充分広くして利得導波構造と
し、かつ光出射側の屈折率導波領域長が１０乃至５００
μｍ、モ二り例の屈折率導波領域が５００μｍ以下、利
得導波領域長が１０乃至５００μｍ、屈折率導波領域幅
が１乃至１０μｍ１利得導波領域幅が５μｍ以上、電流
注入幅が１乃至１０μｍであるリブＶの光導波路を有し
、かつ該光導波路側面を［１−Ｖｌ族化合物半導体層で
あるＺｎＳｅＢで埋メ込んで成る半導体レーザにおいて
、該屈折率導波構造部の該リブ状の光導波路幅の幅（以
下Ｗと記す、）が０．５乃至１０μｍであり、かつ該活
性層と該ＺｎＳｅｌｉの間に残された該クラブト層のＩ
Ｗａ（以下【と記す。）が０乃至２．０μｍであること
を特徴とする。The semiconductor laser of the present invention has Aρx G a 1-z
A double heterojunction semiconductor laser comprising an active layer and a cladding layer made of an As (0≦x<1) compound semiconductor, and a part of the cladding layer immediately above the active layer is etched away, and at least one of the cladding layers is etched away. A refractive index waveguide structure is formed in which the refractive index waveguide width and the current injection width are approximately the same in the vicinity of the resonator rJ plane, and the refractive index waveguide width is sufficiently wider than the current injection width in areas other than the refractive index waveguide structure. and has a gain waveguide structure with a refractive index waveguide region length of 10 to 500 on the light output side.
μm, the refractive index waveguide region is 500 μm or less, the gain waveguide region length is 10 to 500 μm, the refractive index waveguide region width is 1 to 10 μm1, the gain waveguide region width is 5 μm or more, and the current injection width is 1 μm. In a semiconductor laser which has an optical waveguide with a rib V of 10 μm to 10 μm, and the side surface of the optical waveguide is embedded with ZnSeB, which is a 1-Vl group compound semiconductor layer, the rib of the refractive index waveguide structure The width of the optical waveguide width (hereinafter referred to as W) is 0.5 to 10 μm, and the I of the crabbed layer left between the active layer and the ZnSeli is
It is characterized in that Wa (hereinafter referred to as [)] is 0 to 2.0 μm.

〔実施例〕〔Example〕

以下本発明の詳細な説明する。ここでは化合物半導体の
代表であるＡｐＧａＡｓ系化合物半導体を例とするが、
他の化合切半４体についても同様に実施でざる。The present invention will be explained in detail below. Here, ApGaAs-based compound semiconductor, which is a representative compound semiconductor, will be used as an example.
The same procedure can be applied to the other four combined cut halves.

（実施例１） ｍ１図に本発明によるＬＤの構造を示し、第２図にその
作製工程図を示す。(Example 1) Figure m1 shows the structure of an LD according to the present invention, and Figure 2 shows a diagram of its manufacturing process.

ｎ型−ＧａＡｓ基ＦＬ（２０１）上にｎ型−ＧａＡｓバ
フ７ｙ一層（２０２）　、ｎ型−Ａ　Ｊ２ｘ　Ｇ　ａ＋
　−ｒ　Ａ　Ｓ第１のクラッド層（２０３）　、Ａｕ。One layer of n-type GaAs buff 7y (202) on n-type GaAs base FL (201), n-type-A J2x Ga+
-r AS first cladding layer (203), Au.

Ｇ　＆　＋　−ｙ　Ａ　Ｓ活性層（ｘ＞Ｖ）（２０４）
　、Ｐ型−ＡＪ２．Ｇａ＋　−ｘ　Ａｓ＠２のクラブト
Ｆｊｉ（ｚ＞ｙ）（２０５）、　ｐ型−ＧａＡｓ：ｘン
タクト層（２０６）より成る構造を連続して形成する。G & + -y AS active layer (x>V) (204)
, P type-AJ2. A structure consisting of a Ga+-xAs@2 crabt Fji (z>y) (205) and a p-type GaAs:x contact layer (206) is successively formed.

（ｍ２図（ａ））上記各層の成長は、液相成長法（以下
ＬＰＥ法と記す、）を機金叫気相成長法（以下ＭＯＣＶ
Ｄ法と記す。）、　分子線成長法（以下ＭＢＥ法と記す
、）等の方法により行なえる０次いで第２図（Ｃ）の斜
線部（２０８）の如く形吠に、リブエツチング用マスク
（２０７）を形成する。続いて種々のウェットエツチン
グ法またはドライエツチング法によりＰ型−ＧａＡｓコ
ンタクトＪｉ！ｌ　（２０８）およびＰ４−Ａρｚ　Ｇ
　＆　＋−ｚ　Ａｓ第２のクラッド層の１部をエツチン
グ除去する。（ｆｉ２図（ｄ））続いてＩＩ−Ｖｌ族化
合物半導体であるＺｎＳｅ埋め込み層（２０９）をＭＯ
ＣＶＤ法等により成長する６次にＺｎＳｅ埋め込みｆｆ
（２０９）をストライプ吠にエツチング除去する。　エ
ツチング後の素子の上面図を第２図（ｇ）に示す。斜線
部がＺｎＳｅａであり中央部のストライプはｐ型−Ｇａ
ＡｓコアタクトＩｆ！１（２０６）が露出している部分
である。以後ｐ側電極（２１０）の形成、裏面の基板ケ
ンマ工程、ｎ側ｍＷ（２１１）を形成して本発明のＬＤ
となる。(M2 diagram (a)) The growth of each layer is performed using liquid phase epitaxy (hereinafter referred to as LPE method) or mechanical vapor phase epitaxy (hereinafter referred to as MOCV).
It is written as D method. ), a molecular beam growth method (hereinafter referred to as MBE method), etc. Then, a rib etching mask (207) is formed in the shape of the shaded area (208) in FIG. 2(C). . Subsequently, P-type-GaAs contacts Ji! are formed by various wet etching or dry etching methods. l (208) and P4-Aρz G
& +-z Etch a portion of the As second cladding layer. (Fig. fi2 (d)) Next, a ZnSe buried layer (209), which is a II-Vl group compound semiconductor, is added to the MO
Sixth order ZnSe embedded ff grown by CVD method etc.
(209) is removed by etching into stripes. A top view of the device after etching is shown in FIG. 2(g). The shaded area is ZnSea, and the central stripe is p-type-Ga.
As Core Tact If! 1 (206) is the exposed part. Thereafter, the p-side electrode (210) is formed, the backside substrate is removed, and the n-side mW (211) is formed to complete the LD of the present invention.
becomes.

本発明で使用したＺｎＳｅ埋め込み届（２０９）の屈折
率は、いかなるＡＪ２混晶比のＡβＧａＡ３層よりも小
さな値であり、禁制帯幅はいかなるＡρ混混晶のＡρＧ
ａＡｓＪｅ５よりも広い材料である。したがって本発明
により形成される４波路は、ＺｎＳｅＧによるレーザ発
振光の吸収は生じＩＪい為接合に水平な方向に複素屈折
率の実数部により形成される屈折率差が生じ、屈折率４
波路となる。加えて接合に水平な方向の屈折率差を決定
する重要なパラメータである第２のクラッド層のエツチ
ング後の残り膜厚は、ＺｎＳｅ５の屈折率が小さい為他
材料での埋め込みの場合より厚くしても単−横モード発
振が可能な屈折率差が得られる。The refractive index of the ZnSe embedded material (209) used in the present invention is smaller than that of the AβGaA3 layer with any AJ2 mixed crystal ratio, and the forbidden band width is smaller than that of the AβGaA3 layer with any AJ2 mixed crystal ratio.
It is a wider material than aAsJe5. Therefore, in the four wave paths formed according to the present invention, since absorption of laser oscillation light by ZnSeG occurs and there is no IJ, a refractive index difference formed by the real part of the complex refractive index occurs in the direction horizontal to the junction, and the refractive index is 4.
It becomes a wave path. In addition, the remaining film thickness after etching of the second cladding layer, which is an important parameter that determines the refractive index difference in the direction horizontal to the junction, is thicker than in the case of filling with other materials because the refractive index of ZnSe5 is small. However, a refractive index difference that enables single-transverse mode oscillation can be obtained.

共振器端面近傍では上記屈折率等波路の幅と電流注入幅
を同程度として屈折率４波機構としているので、安定な
単−横モード発振が可能でかつ非点隔差の極めて小さな
レーザ光が出射される。In the vicinity of the resonator end face, the width of the above-mentioned constant refractive index wave path and the current injection width are made to be about the same, resulting in a four-wave refractive index mechanism, which enables stable single-transverse mode oscillation and emits laser light with an extremely small astigmatism difference. be done.

一方共振器中央部では上記屈折率４波路の幅を電流注入
幅より充分床（することで利得４波ｍ横となり縦多軸モ
ード発振となり戻り光雑音を極力抑えることが出来る。On the other hand, in the center of the resonator, the width of the four-refractive index wave path is set to be sufficiently lower than the current injection width, so that the gain becomes four waves m horizontal, resulting in vertical multi-axis mode oscillation, and return optical noise can be suppressed as much as possible.

さらにＺｎＳｅｌｆｆｌは抵抗率が高い材料（１０＠Ω
ｃｍ以上）であるので電流狭窄がを効に行われ活性領域
外を流れる無効電流を極力抑えることが出来る。１部１
表に本発明のＬＤにおける各種パラメータを変化させた
際のＬＤの特性を示す。Ｗおよびｔは第１図に示しであ
る試料ナンバー１乃至６までは本発明で限定した範囲内
に各種パラメータが入っている場合であり、すべての試
料で基本モード発振し、縦モードはマルチモード発ｔＨ
している。加えて非点隔差も数μｍと極めて小さな値と
なっている。一方試料ナンバー７乃至１０は、パラメー
タの１部が本発明で限定した範囲外の値となっている。Furthermore, ZnSelffl is a material with high resistivity (10@Ω
cm or more), current confinement is effectively performed and reactive current flowing outside the active region can be suppressed as much as possible. 1 part 1
The table shows the characteristics of the LD of the present invention when various parameters are changed. W and t are shown in Fig. 1. Sample numbers 1 to 6 are cases where various parameters are within the range limited by the present invention, and all samples oscillate in the fundamental mode, and the longitudinal mode is multimode. Starting tH
are doing. In addition, the astigmatism difference is also an extremely small value of several μm. On the other hand, in sample numbers 7 to 10, some of the parameters have values outside the range defined by the present invention.

　そのような試料については、横モードが高次で発振、
しきい値電流が大縦モードかシンプルで発振、あるいは
非点隔差が大というような特性の変化が生ずる。このよ
うな特性は光情報処理装置等の光源としてＬＤを使用す
る際問題となり、実用に供することが不可能となる。し
たがって本発明で限定した範囲を満足することが！ｔＬ
ａである。For such samples, the transverse mode oscillates at a higher order,
Changes in characteristics occur, such as the threshold current being in a large longitudinal mode, simple oscillation, or a large astigmatism difference. Such characteristics pose a problem when using an LD as a light source for an optical information processing device or the like, making it impossible to put it to practical use. Therefore, it is possible to satisfy the scope limited by the present invention! tL
It is a.

第１表 １ｔｈ：Ｌ、きい値電流値 〔発明の効果〕 以上述べたように本発明によれば、ＬＤの特性を決める
構造の種々のパラメータの数値を最適化したことにより
以下のような効果が得られる。Table 1 1th: L, threshold current value [Effects of the invention] As described above, according to the present invention, the following effects are achieved by optimizing the numerical values of various parameters of the structure that determines the characteristics of the LD. is obtained.

１）光出射端面近傍の屈折率導波構造部のＷを最適化し
たことで安定した基本横モード発振が得られる。1) Stable fundamental transverse mode oscillation can be obtained by optimizing W of the refractive index waveguide structure near the light emitting end face.

２）光導波路外における活性層上のクラッド層の残り厚
ｔの最適化により基本横モード発振が安定して得られる
。2) Fundamental transverse mode oscillation can be stably obtained by optimizing the remaining thickness t of the cladding layer on the active layer outside the optical waveguide.

３）ｔを最適化していることで、接合に平行な方向に生
ずる屈折率差の調整が可能となり、ビームのスポットサ
イズを変化させることが出来る。したがって基本横モー
ド発振を保ちつつ高出力動作が可能となる。3) By optimizing t, it is possible to adjust the refractive index difference that occurs in the direction parallel to the junction, and the beam spot size can be changed. Therefore, high output operation is possible while maintaining fundamental transverse mode oscillation.

４）ｗおよび【を最適化したことで、基本債モード発振
しかつ利得４波領域の影響により縦多モード発振するＬ
Ｄ特性が得られる。4) By optimizing w and
D characteristic is obtained.

５）ｗおよびｔの最適化により非点収差の極めて小さな
レーザ発振光が得られる。5) Laser oscillation light with extremely small astigmatism can be obtained by optimizing w and t.

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

第１図（ａ）〜（ｃ）は本発明のＬＤの一実施例を示す
構造図 （ａ）は上面図、（ｂ）（ｃ）は各部所での断面図 第２図（ａ）〜（ｇ）は本発明のＬＤの作製工程図 ２０１・・・・・・ｎ型−ＧａＡｓ基板２０２・・・・
・・ｎ型−ＧａＡｓバフファ一層２０３−−−−−−ｎ
’Ｊｌ−Ａ　１ｘ　Ｇ　ａｔ　−ｘ　Ａ　ｓｍ　１のク
ラッド層 ２０４−　・＝　Ａ　１　ｙ　Ｇ　ａ　１−　ｙ　Ａ　
ｓ活性層２０５・・・・・・ｐ型−Ａ　１　ｚ　Ｇ　ａ
　＋　−ｔ　Ａ　ｓ　’ＦＣ２のクラッド層 ２０６・・・・・・Ｐ　！！　−Ｇ　ａ　Ａ　ｓコンタ
クト層２０７・・・・・・リブエツチング用マスク２０
９・・・・・・ＺｎＳｅ埋め込み層２１０・・・・・・
ｐ側電極 ２１１・・・・・・ｎ側電極 以　　上 ！［人　セイコーエプソン株式会社 代理人　弁理士　最　上　　務　他１名・バー・１′−
、こ− （７Ｌン 磨 Ｔ　田FIGS. 1(a) to (c) are structural diagrams showing one embodiment of the LD of the present invention. (a) is a top view, and (b) and (c) are sectional views of various parts. (g) is a manufacturing process diagram of the LD of the present invention 201...n-type-GaAs substrate 202...
・・N-type-GaAs buffer layer 203----n
'Jl-A 1x G at -x A sm 1 cladding layer 204- ・= A 1 y Ga 1- y A
s active layer 205...p type-A 1 z Ga
+ -t As 'Clad layer 206 of FC2...P! ! -G a As contact layer 207 ... Rib etching mask 20
9...ZnSe buried layer 210...
P-side electrode 211... More than n-side electrode! [Representative of Seiko Epson Corporation Patent attorney Tsutomu Mogami and 1 other person Bar 1'-
, this (7Lnma T field)

Claims (1)

【特許請求の範囲】[Claims] Ａｌ＿ＸＧａ＿１＿−＿ＸＡｓ（０≦Ｘ≦１）化合物半
導体より成る活性層及びクラッド層から構成されるダブ
ルヘテロ接合型半導体レーザの該活性層直上の該クラッ
ド層の１部をエッチング除去して成り、かつ少なくとも
一方の共振器端面近傍で屈折率導波路幅と電流注入幅を
ほぼ同程度として屈折率導波構造とし、該屈折率導波構
造以外の領域では屈折率導波路幅を電流注入幅より充分
広くして利得導波構造としかつ光出射側の屈折率導波領
域長が１０乃至５００μｍ、モニタ側の屈折率導波領域
が５００μｍ以下、利得導波領域長が１０乃至５００μ
ｍ、屈折率導波領域幅が１乃至１０μｍ、利得導波領域
幅が５μｍ以上、電流注入幅が１乃至１０μｍであるリ
ブ状の光導波路を有し、かつ該光導波路側面をII−IV族
化合物半導体層であるＺｎＳｅ層で埋め込んで成る半導
体レーザにおいて、該屈折率導波構造部の該リブ状の光
導波路幅の幅（以下ｗと記す。）が０．５乃至１０μｍ
であり、かつ該活性層と該ＺｎＳｅ層の間に残された該
クラッド履の層厚（以下ｔと記す。）が０乃至２．０μ
ｍであることを特徴とする半導体レーザ。A double heterojunction semiconductor laser comprising an active layer and a cladding layer made of an Al_XGa_1_-_XAs (0≦X≦1) compound semiconductor, in which a part of the cladding layer immediately above the active layer is etched away, and at least A refractive index waveguide structure is created in which the refractive index waveguide width and current injection width are approximately the same near one resonator end face, and the refractive index waveguide width is sufficiently wider than the current injection width in areas other than the refractive index waveguide structure. and has a gain waveguide structure, and the refractive index waveguide region length on the light output side is 10 to 500 μm, the refractive index waveguide region on the monitor side is 500 μm or less, and the gain waveguide region length is 10 to 500 μm.
m, has a rib-shaped optical waveguide with a refractive index waveguide region width of 1 to 10 μm, a gain waveguide region width of 5 μm or more, and a current injection width of 1 to 10 μm, and the side surface of the optical waveguide is a group II-IV waveguide. In a semiconductor laser embedded in a ZnSe layer which is a compound semiconductor layer, the width of the rib-shaped optical waveguide (hereinafter referred to as w) of the refractive index waveguide structure is 0.5 to 10 μm.
and the layer thickness (hereinafter referred to as t) of the cladding layer remaining between the active layer and the ZnSe layer is 0 to 2.0μ.
A semiconductor laser characterized in that m.