JP3307669B2 - Compound semiconductor superlattice - Google Patents
Compound semiconductor superlatticeInfo
- Publication number
- JP3307669B2 JP3307669B2 JP8375592A JP8375592A JP3307669B2 JP 3307669 B2 JP3307669 B2 JP 3307669B2 JP 8375592 A JP8375592 A JP 8375592A JP 8375592 A JP8375592 A JP 8375592A JP 3307669 B2 JP3307669 B2 JP 3307669B2
- Authority
- JP
- Japan
- Prior art keywords
- quantum well
- layer
- barrier layer
- mixed crystal
- quaternary mixed
- 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 - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
- H01S5/2004—Confining in the direction perpendicular to the layer structure
- H01S5/2009—Confining in the direction perpendicular to the layer structure by using electron barrier layers
- H01S5/2013—MQW barrier reflection layers
Landscapes
- Semiconductor Lasers (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Recrystallisation Techniques (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、障壁層内にｐ型不純物
が添加された単一または多重量子井戸構造を有する半導
体レーザに係り、特に、障壁層と量子井戸層とのヘテロ
界面の障壁層側もしくは障壁層と量子井戸層の両層側
に、ｎ型、ｐ型または電気的に中性の不純物を添加する
ことで、優れた半導体レーザ特性が得られる化合物半導
体超格子構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser having a single or multiple quantum well structure in which a barrier layer is doped with a p-type impurity, and more particularly to a barrier at a hetero interface between a barrier layer and a quantum well layer. The present invention relates to a compound semiconductor superlattice structure in which excellent semiconductor laser characteristics can be obtained by adding an n-type, p-type or electrically neutral impurity to a layer side or both layers of a barrier layer and a quantum well layer.
【０００２】[0002]
【従来の技術】従来、半導体レーザにおいては、良好な
レーザ特性を得るために重要な要因となる光閉じ込め率
の増大、光損失の低減、発光の源となるキャリア（電子
と正孔）の注入効率の増大等をはかるため、Ｉn1-xＧax
ＡsyＰ1-yの組成で示される四元混晶、あるいはＩn1-x
ＧaxＡsの組成で示される三元混晶からなる量子井戸層
と、該量子井戸層よりもバンドギャップが大きく、かつ
ＩnＰに格子整合したＩn1-xＧaxＡsyＰ1-yの四元混晶か
らなる障壁層が数周期で積層されている多重量子井戸構
造を活性層として用いていた。この時、障壁層のみにｐ
型不純物であるＺnを添加（ドーピング）、つまり変調
ドーピングすると、活性層における光損失が増大するこ
と無く、量子井戸層に注入される正孔を増大させること
ができるという利点が生じる。このことは、半導体レー
ザにおいては、高レーザ光出力および線幅増大係数の低
減という良好な特性が得られるので大きな特長となって
いる。しかし、高濃度（１×１０18ｃｍ~3以上）でＺn
を変調ドーピングすると、半導体レーザ構造の結晶成長
および半導体レーザの作製過程における熱の影響により
障壁層中にのみドーピングされたＺnが障壁層から井戸
層に拡散するため、量子井戸層の結晶特性の劣化および
光損失の増大が起こり、そのため効率の低下、すなわち
レーザ光出力が低下してしまうという問題が生じる。そ
こで、一般に良好なレーザ素子特性を得るために変調ド
ーピングされるＺnの濃度は、障壁層から量子井戸層へ
のＺnの熱拡散が生じないドーピング濃度に制限されて
いた。このため、良好な特性をもつｐ型不純物が変調ド
ーピングされた量子井戸半導体レーザにおいては、低濃
度（１×１０18ｃｍ~3未満）で変調ドーピングされたも
のがほとんどであり、より良好なレーザ素子特性が期待
できる高濃度（１×１０18ｃｍ~3以上）で障壁層のみに
変調ドーピングすることは極めて困難であった。2. Description of the Related Art Conventionally, in a semiconductor laser, an increase in light confinement ratio, a reduction in light loss, and an injection of carriers (electrons and holes) serving as light emission sources are important factors for obtaining good laser characteristics. In order to increase the efficiency, etc., In 1-x Ga x
Quaternary mixed crystal represented by a composition of As y P 1-y or an In 1-x,
And Ga x As quantum well layer made of ternary mixed crystal represented by a composition of, In 1-x Ga x As fourth y P 1-y where larger band gap than the quantum well layer, and is lattice-matched to InP A multiple quantum well structure in which barrier layers made of an original mixed crystal are stacked in several periods has been used as an active layer. At this time, p is applied only to the barrier layer.
Addition (doping) of Zn, which is a type impurity, that is, modulation doping has an advantage that holes injected into the quantum well layer can be increased without increasing light loss in the active layer. This is a great feature of the semiconductor laser because good characteristics such as high laser light output and reduction of the line width increase coefficient can be obtained. However, at high concentrations (1 × 10 18 cm- 3 or more), Zn
Modulation doping, Zn doped only in the barrier layer is diffused from the barrier layer to the well layer due to the influence of heat during the crystal growth of the semiconductor laser structure and the fabrication process of the semiconductor laser, so that the crystal properties of the quantum well layer deteriorate. In addition, an increase in optical loss occurs, which causes a problem that the efficiency is reduced, that is, the laser light output is reduced. Therefore, in general, the concentration of Zn that is modulation-doped to obtain good laser device characteristics is limited to a doping concentration that does not cause thermal diffusion of Zn from the barrier layer to the quantum well layer. For this reason, most of quantum well semiconductor lasers doped with p-type impurities having good characteristics are modulation-doped at a low concentration (less than 1 × 10 18 cm −3 ). It was extremely difficult to perform modulation doping only on the barrier layer at a high concentration (1 × 10 18 cm to 3 or more) at which device characteristics can be expected.
【０００３】[0003]
【発明が解決しようとする課題】本発明の目的は、上述
した従来技術における問題点を解消するものであって、
ｐ型不純物であるＺnを変調ドーピングした単一または
多重量子井戸構造を持つ半導体レーザ等に適用できる化
合物半導体超格子を作製する場合において、ｐ型不純物
であるＺnを高濃度で障壁層のみに変調ドーピングする
ことが可能で、素子特性に優れた半導体レーザ等に好適
に用いられる化合物半導体超格子構造を提供することに
ある。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art.
When fabricating a compound semiconductor superlattice applicable to a semiconductor laser having a single or multiple quantum well structure in which Zn as a p-type impurity is modulation-doped, the
It is an object of the present invention to provide a compound semiconductor superlattice structure which is capable of performing high-concentration modulation doping of Zn only in a barrier layer only at a high concentration and which is suitably used for a semiconductor laser or the like having excellent device characteristics.
【０００４】[0004]
【課題を解決するための手段】上記本発明の目的を達成
するために、本発明の化合物半導体超格子構造の構成
は、ＩnＰ結晶基板上にＩnＧaＡsＰで示される四元混晶
もしくはＩnＧaＡsで示される三元混晶からなる量子井
戸層と、該量子井戸層よりもバンドギャップが大きく、
ＩnＰ結晶基板に格子整合し、かつｐ型不純物であるＺn
が添加されたＩnＧaＡsＰで示される四元混晶からなる
障壁層とを交互に積層して構成された単一または多重量
子井戸構造において、上記障壁層と量子井戸層とのヘテ
ロ界面近傍の障壁層側もしくは上記ヘテロ界面近傍の両
層側に、例えばＳi、Ｓe、Ｓn、Ｓ等のｎ型不純物、例
えばＣd、Ｂe、Ｍg等のｐ型不純物、またはＹｂ等の電
気的に中性（ｐ型でもｎ型でもない）の不純物を添加す
るものである。上記の不純物を添加する理由は、例え
ば、熱拡散距離がｐ型不純物であるＺnに比べて極めて
小さいＳi等のｎ型不純物、Ｃd、Ｂe、Ｍg等のｐ型不純
物またはＹb等の電気的に中性の不純物を、障壁層と量
子井戸層とのヘテロ界面近傍の障壁層側もしくは障壁層
と量子井戸層とのヘテロ界面近傍の障壁層と量子井戸層
の両層側にドーピングすることにより、Ｓiをドーピン
グした領域ではＺnの拡散に必要な元素の周期表III族原
子（ＩnまたはＧa）位置の空孔子をＳi等が占有するた
め、ｐ型不純物であるＺnの障壁層から量子井戸層への
熱拡散を防止することができるので、高濃度（１×１０
１８ ｃｍ −３ 以上）のｐ型不純物であるＺnを障壁層の
みに変調ドーピングすることが可能となり、良好な素子
特性を有する多重量子井戸レーザ等に適用できる化合物
半導体超格子が得られることになる。In order to achieve the object of the present invention, the structure of the compound semiconductor superlattice structure of the present invention is represented by a quaternary mixed crystal represented by InGaAsP or InGaAs formed on an InP crystal substrate. A quantum well layer made of a ternary mixed crystal, and a band gap larger than the quantum well layer;
Aligned lattice with InP crystal substrate, and a p-type impurity Zn
In a single or multiple quantum well structure formed by alternately laminating barrier layers made of a quaternary mixed crystal represented by InGaAsP doped with Cr , and a barrier layer near a heterointerface between the barrier layer and the quantum well layer. in both layers side of the side or the hetero interface vicinity, for example Si, Se, Sn, n type impurity S and the like, examples <br/> example, if C d, be, p-type impurities such as Mg or electrical such as Yb, In addition, a neutral (not p-type or n-type) impurity is added. The reason for adding the above-mentioned impurities is that, for example, n-type impurities such as Si whose thermal diffusion distance is extremely smaller than Zn which is a p- type impurity , p- type impurities such as Cd, Be, Mg, etc. By doping a neutral impurity into the barrier layer near the heterointerface between the barrier layer and the quantum well layer or on both the barrier layer and the quantum well layer near the heterointerface between the barrier layer and the quantum well layer, In the Si-doped region, Si or the like occupies a vacancy at the position of a Group III atom (In or Ga) in the periodic table of an element necessary for diffusion of Zn. Can be prevented from being thermally diffused, so that a high concentration (1 × 10
18 cm -3 or more) of Z n is a p-type impurity becomes possible to modulate doped only in the barrier layer, that compound semiconductor superlattice which can be applied to a multi-quantum well laser and the like having good device characteristics can be obtained Become.
【０００５】[0005]
【作用】障壁層に添加されたｐ型不純物であるＺnの量
子井戸層への熱拡散を防止する変調ドーピングは、障壁
層と量子井戸層とのヘテロ界面近傍の障壁層側もしくは
ヘテロ界面近傍の障壁層と量子井戸層の両層側に上記に
ｎ型不純物であるＳi等、ｐ型不純物であるＣｄ等また
は電気的に中性なＹｂ等の不純物をドーピングすること
により可能となる。このＳi等の熱拡散防止元素のドー
ピングを行わない限り、上記障壁層にｐ型不純物である
Ｚnの高濃度の変調ドーピングは達成することができな
い。すなわち、例えば熱拡散距離がＺnに比べて極めて
小さいＳiを障壁層と量子井戸層とのヘテロ界面近傍に
ドーピングすることにより、Ｓiをドーピングした領域
ではＺnの拡散に必要な元素の周期表III族原子（Ｉnま
たはＧa等）位置の空孔子をＳiが占有するため、Ｚnの
障壁層から量子井戸層への熱拡散が抑制されるのであ
る。このため、障壁層から量子井戸層へのＺnの熱拡散
を起こすことなく、高濃度のＺnを障壁層のみにドーピ
ングすることが可能となる。本発明の実施例において、
p型不純物のドーピング濃度が３×１０１８ｃｍ−３、
ｎ型不純物のドーピング濃度が１×１０１８ｃｍ−３の
場合を例に挙げているが、障壁層で生成された正孔が量
子井戸層に注入されるならば、上記以外のドーピング濃
度であっても本発明の効果は得られる。また、仮に障壁
層内にｎ型ドーピング濃度がｐ型ドーピング濃度を上回
りｎ型に反転した層が部分的に生じたとしても、トンネ
ル効果などにより障壁層から量子井戸層へ正孔を注入す
ることができるものと考えられる。すなわち、Ｚnの量
子井戸層内への熱拡散を防止することによって、量子井
戸活性層での光損失の増大および量子井戸層の結晶特性
の劣化を防止することができると共に、多数の正孔を量
子井戸層に供給することが可能となるものである。した
がって、Ｚnの熱拡散によるレーザ特性の劣化を起こす
こと無く、良好なレーザ特性が得られる。SUMMARY OF modulation doping to prevent thermal diffusion on the amount <br/> quantum well layer of Z n is a p-type impurity added to the barrier layer, the barrier layer of the hetero vicinity of the interface between the barrier layer and the quantum well layer By doping the n-type impurity such as Si, the p-type impurity such as Cd, or the electrically neutral Yb, etc., into the barrier layer and the quantum well layer on the side or near the hetero interface. It becomes possible. Unless the thermal diffusion preventing element such as Si is doped, the barrier layer is a p- type impurity .
High modulation doping of Zn cannot be achieved. That is, for example, by doping Si, whose thermal diffusion distance is extremely small as compared with Zn, near the hetero interface between the barrier layer and the quantum well layer, a group III of the periodic table of elements required for Zn diffusion in the Si-doped region. Since Si occupies a vacancy at the position of an atom (such as In or Ga), thermal diffusion from the Zn barrier layer to the quantum well layer is suppressed. Therefore, it is possible to dope high concentration Zn only into the barrier layer without causing thermal diffusion of Zn from the barrier layer to the quantum well layer. In an embodiment of the present invention,
the doping concentration of the p-type impurity is 3 × 10 18 cm −3 ,
Although the case where the doping concentration of the n-type impurity is 1 × 10 18 cm −3 is taken as an example, if the holes generated in the barrier layer are injected into the quantum well layer, the doping concentration may be other than the above. Even so, the effects of the present invention can be obtained. Even if a layer in which the n-type doping concentration exceeds the p-type doping concentration and is inverted to n-type partially occurs in the barrier layer, holes are injected from the barrier layer into the quantum well layer by a tunnel effect or the like. It is thought that it is possible. That is, by preventing the thermal diffusion of Zn into the quantum well layer, it is possible to prevent an increase in light loss in the quantum well active layer and a deterioration in crystal characteristics of the quantum well layer, and to prevent a large number of holes from being generated. It can be supplied to the quantum well layer. Therefore, good laser characteristics can be obtained without deteriorating laser characteristics due to thermal diffusion of Zn.
【０００６】[0006]
【実施例】以下に本発明の実施例を挙げ、図面を用いて
さらに詳細に説明する。 ＜実施例１＞図１（ａ）、（ｂ）に本発明の第一の実施
例を示す。図１（ａ）は、発振波長１．５５μｍ帯のレ
ーザ素子における多重量子井戸活性層６の層断面構造を
示す模式図である。図１（ａ）において、多重量子井戸
活性層６は、Ｉn1-xＧaxＡsyＰ1-y（バンドギャップ波
長１．３μｍ）で示される四元混晶ガイド層１（層厚１
０００Å）、４層からなるＩn1-xＧaxＡsyＰ1-yで示さ
れる組成の四元混晶量子井戸層２（層厚３０Å）、３層
からなるＩn1-xＧaxＡsyＰ1-y（バンドギャップ波長
１．３μｍ）で示される四元混晶障壁層３（層厚２００
Å）およびＩn1-xＧaxＡsyＰ1-y（バンドギャップ波長
１．３μｍ）で示される組成の四元混晶バッファ層４
（層厚５００Å）の多層構造よりなる化合物半導体超格
子である。図１（ｂ）に多重量子井戸活性層６内のＺn
およびＳiのドーピング濃度分布を示す。ここで、ドー
ピング濃度分布とはドーピングを行った領域と、ドーピ
ング条件から推定されるドーピング濃度を示すものであ
る。Ｚnは、四元混晶障壁層３内の全域にドーピングさ
れている。Ｓiは、四元混晶障壁層３内の四元混晶量子
井戸層２との界面から２０Å以内の領域にドーピングさ
れている。ここで、四元混晶障壁層３内でのＳiのドー
ピング領域は、四元混晶量子井戸層２との界面から２０
Å以内としているが、四元混晶障壁層３内で四元混晶量
子井戸層２との界面近傍にドーピングされていれば２０
Å以上、例えば四元混晶障壁層３全域であっても本発明
の効果は得られる。Ｚnのドーピング領域は、四元混晶
障壁層３内であれば、どこに設定されていても構わな
い。四元混晶障壁層３中のＺnのドーピング濃度は３×
１０18ｃｍ~3、Ｓiのそれは１×１０18ｃｍ~3とした。DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in more detail with reference to the drawings. <Embodiment 1> FIGS. 1A and 1B show a first embodiment of the present invention. FIG. 1A is a schematic diagram showing a layer cross-sectional structure of the multiple quantum well active layer 6 in a laser device having an oscillation wavelength of 1.55 μm band. 1 (a), the multiple quantum well active layer 6, In 1-x Ga x As y P 1-y quaternary mixed crystal represented by (bandgap wavelength 1.3 .mu.m) guide layer 1 (thickness 1
000Å), In 1-x Ga x As y P quaternary mixed crystal of 1-y composition represented by the quantum well layer 2 (thickness 30Å of four layers), a three-layer In 1-x Ga x As y The quaternary mixed crystal barrier layer 3 (layer thickness 200 μm) represented by P 1-y (bandgap wavelength 1.3 μm)
Å) and In 1-x Ga x As y P 1-y ( quaternary mixed crystal buffer layer having a composition represented by the bandgap wavelength of 1.3 .mu.m) 4
This is a compound semiconductor superlattice having a multilayer structure (thickness: 500 °). FIG. 1B shows Zn in the multiple quantum well active layer 6.
And Si doping concentration distributions are shown. Here, the doping concentration distribution indicates a doping region and a doping concentration estimated from doping conditions. Zn is doped all over the quaternary mixed crystal barrier layer 3. Si is doped in the quaternary mixed crystal barrier layer 3 in a region within 20 ° from the interface with the quaternary mixed quantum well layer 2. Here, the Si doping region in the quaternary mixed crystal barrier layer 3 is 20 nm from the interface with the quaternary mixed quantum well layer 2.
Although it is within Å, if it is doped near the interface with the quaternary mixed quantum well layer 2 in the quaternary mixed crystal barrier layer 3, 20
Å As described above, for example, the effect of the present invention can be obtained even in the entire region of the quaternary mixed crystal barrier layer 3. The Zn doping region may be set anywhere within the quaternary mixed crystal barrier layer 3. The doping concentration of Zn in the quaternary mixed crystal barrier layer 3 is 3 ×
Of 10 18 cm ~ 3, Si it was 1 × 10 18 cm ~ 3.
【０００７】＜実施例２＞図２に本発明の第二の実施例
を示す。図２（ａ）は、発振波長１．５５μｍ帯のレー
ザ素子における多重量子井戸活性層６の層断面構造を示
す模式図である。図２（ａ）において、多重量子井戸活
性層６は、Ｉn1-xＧaxＡsyＰ1-y（バンドギャップ波長
１．３μｍ）で示される組成の四元混晶ガイド層１（層
厚１０００Å）、４層からなるＩn1-xＧaxＡsyＰ1-yで
示される組成の四元混晶量子井戸層２（層厚３０Å）、
３層からなるＩn1-xＧaxＡsyＰ1-y（バンドギャップ波
長１．３μｍ）で示される組成の四元混晶障壁層３（層
厚２００Å）およびＩn1-xＧaxＡsyＰ1-y（バンドギャ
ップ波長１．３μｍ）で示される組成の四元混晶バッフ
ァ層４（層厚５００Å）の多層構造よりなる化合物半導
体超格子である。図２（ｂ）に、多重量子井戸活性層６
内のＺnおよびＳiのドーピング濃度分布を示す。Ｚn
は、四元混晶障壁層３内にドーピングされている。Ｓi
は、四元混晶量子井戸層２内および四元混晶障壁層３内
へ四元混晶量子井戸層２の界面から２０Å以内の領域に
ドーピングされている。ここで、Ｓiのドーピング領域
は２０Å以内としているが、四元混晶障壁層３内で、該
障壁層３と四元混晶量子井戸層２のヘテロ界面近傍にド
ーピングされていれば２０Å以上、例えば四元混晶障壁
層３全域であっても同様の効果が得られる。また、Ｓi
のドーピングは四元混晶量子井戸層２内だけに行われて
いても構わない。Ｚnのドーピング領域は、四元混晶障
壁層３内であれば、どこに設定されていても構わない。
四元混晶障壁層３中のＺnのドーピング濃度は３×１０
18ｃｍ~3、Ｓiのそれは１×１０18ｃｍ~3とした。<Embodiment 2> FIG. 2 shows a second embodiment of the present invention. FIG. 2A is a schematic diagram showing a layer cross-sectional structure of the multiple quantum well active layer 6 in a laser device having an oscillation wavelength of 1.55 μm band. 2 (a), the multiple quantum well active layer 6, In 1-x Ga x As y P 1-y ( band gap wavelength 1.3 .mu.m) quaternary mixed crystal guide layer 1 having a composition represented by (thickness 1000 Å), composed of four layers in 1-x Ga x as y P four yuan of 1-y composition represented by mixed crystal quantum well layer 2 (layer thickness 30 Å),
Composed of three layers In 1-x Ga x As y P 1-y quaternary alloy barrier layer 3 (layer thickness 200 Å) having a composition represented by (band gap wavelength 1.3 .mu.m) and In 1-x Ga x As y This is a compound semiconductor superlattice having a multilayer structure of a quaternary mixed crystal buffer layer 4 (layer thickness: 500 °) having a composition represented by P 1-y (band gap wavelength: 1.3 μm). FIG. 2B shows the multiple quantum well active layer 6.
Shows the doping concentration distributions of Zn and Si in FIG. Zn
Is doped in the quaternary mixed crystal barrier layer 3. Si
Is doped into the quaternary mixed quantum well layer 2 and the quaternary mixed crystal barrier layer 3 in a region within 20 ° from the interface of the quaternary mixed quantum well layer 2. Here, the Si doping region is set to be within 20 °, but in the quaternary mixed crystal barrier layer 3, if doped near the hetero interface between the barrier layer 3 and the quaternary mixed quantum well layer 2, the Si doped region is set to 20 ° or more. For example, the same effect can be obtained even in the entire region of the quaternary mixed crystal barrier layer 3. Also, Si
May be performed only in the quaternary mixed crystal quantum well layer 2. The Zn doping region may be set anywhere within the quaternary mixed crystal barrier layer 3.
The doping concentration of Zn in the quaternary mixed crystal barrier layer 3 is 3 × 10
18 cm ~ 3 , and that of Si was 1 × 10 18 cm ~ 3 .
【０００８】＜実施例３＞図３に本発明の第三の実施例
を示す。図３（ａ）は、発振波長１．５５μｍ帯のレー
ザ素子における多重量子井戸活性層６の層断面構造を示
す模式図である。図３（ａ）において、多重量子井戸活
性層３は、Ｉn1-xＧaxＡsyＰ1-y（バンドギャップ波長
１．３μｍ）で示される組成の四元混晶ガイド層１（層
厚１０００Å）、４層からなるＩn1-xＧaxＡsyＰ1-yで
示される組成の四元混晶量子井戸層２（層厚３０Å）、
３層からなるＩn1-xＧaxＡsyＰ1-y（バンドギャップ波
長１．３μｍ）で示される組成の四元混晶障壁層３（層
厚２００Å）およびＩn1-xＧaxＡsyＰ1-y（バンドギャ
ップ波長１．３μｍ）で示される組成の四元混晶バッフ
ァ層４（層厚５００Å）の多層構造よりなる化合物半導
体超格子である。図３（ｂ）に、多重量子井戸活性層６
内のＺnおよびＳiのドーピング濃度分布を示す。Ｚn
は、四元混晶障壁層３内にドーピングされている。Ｓi
は、四元混晶量子井戸層２と四元混晶障壁層３の界面か
ら四元混晶量子井戸層２側および四元混晶障壁層３側の
２０Å以内の領域にドーピングされている。ここで、Ｓ
iのドーピング領域は２０Å以内としているが、四元混
晶量子井戸層２と四元混晶障壁層３のヘテロ界面から四
元混晶量子井戸層２側および四元混晶障壁層３側にドー
ピングされていれば２０Å以上、例えば四元混晶障壁層
３全域であっても同様の効果が得られる。Ｚnのドーピ
ング領域は四元混晶障壁層３内であれば、どこに設定さ
れていても構わない。四元混晶障壁層３中のＺnのドー
ピング濃度は３×１０18ｃｍ~3、Ｓiのそれは１×１０
18ｃｍ~3とした。<Embodiment 3> FIG. 3 shows a third embodiment of the present invention. FIG. 3A is a schematic view showing a layer cross-sectional structure of the multiple quantum well active layer 6 in a laser device having an oscillation wavelength of 1.55 μm band. 3 (a), the multiple quantum well active layer 3, In 1-x Ga x As y P 1-y ( band gap wavelength 1.3 .mu.m) quaternary mixed crystal guide layer 1 having a composition represented by (thickness 1000 Å), composed of four layers in 1-x Ga x as y P four yuan of 1-y composition represented by mixed crystal quantum well layer 2 (layer thickness 30 Å),
Composed of three layers In 1-x Ga x As y P 1-y quaternary alloy barrier layer 3 (layer thickness 200 Å) having a composition represented by (band gap wavelength 1.3 .mu.m) and In 1-x Ga x As y This is a compound semiconductor superlattice having a multilayer structure of a quaternary mixed crystal buffer layer 4 (layer thickness: 500 °) having a composition represented by P 1-y (band gap wavelength: 1.3 μm). FIG. 3B shows the multiple quantum well active layer 6.
Shows the doping concentration distributions of Zn and Si in FIG. Zn
Is doped in the quaternary mixed crystal barrier layer 3. Si
Is doped in the region within 20 ° of the quaternary mixed quantum well layer 2 side and the quaternary mixed crystal barrier layer 3 side from the interface between the quaternary mixed quantum well layer 2 and the quaternary mixed crystal barrier layer 3. Where S
Although the doping region of i is set within 20 °, the doping region from the hetero interface between the quaternary mixed quantum well layer 2 and the quaternary mixed crystal barrier layer 3 to the quaternary mixed quantum well layer 2 side and the quaternary mixed crystal barrier layer 3 side. The same effect can be obtained even if it is doped by 20 ° or more, for example, in the entire region of the quaternary mixed crystal barrier layer 3. The Zn doping region may be set anywhere within the quaternary mixed crystal barrier layer 3. The doping concentration of Zn in the quaternary mixed crystal barrier layer 3 is 3 × 10 18 cm 3 , and that of Si is 1 × 10 18 cm 3 .
It was 18 cm- 3 .
【０００９】なお、上記本発明の実施例においては発振
波長が１.５５μｍの場合について説明したが、全く同
様の層構成で、Ｉn１−ｘＧaｘＡsｙＰ１−ｙ混晶の組
成比を変えるだけで、他の発振波長を有するレーザ素子
を作製することも当然可能である。また、多重量子井戸
構造には４層からなる量子井戸層と３層からなる障壁層
を用いたが、井戸数と障壁数に限りは無い。また、量子
井戸層にはＩnＧaＡsＰで示される四元混晶を用いて
も、またＩnＧaＡsで示される三元混晶を用いても構わ
ない。さらにＺnと同時にドーピングする不純物にｎ型
不純物Ｓiを用いたが、Ｓn、Ｓ、Ｓeなどの他のｎ型不
純物、Ｃd、Ｂe、Ｍgなどのｐ型不純物、またはＹbなど
の電気的に中性な（ｐ型でもｎ型でもない）不純物を用
いても本発明の効果は得られる。[0009] In the examples of the present invention is an oscillation wavelength has been described for the case of 1.55 .mu.m, in exactly the same layer configuration, the composition ratio of In 1-x Ga x As y P 1-y mixed crystal It is naturally possible to fabricate a laser device having another oscillation wavelength only by changing the wavelength. Further, although the quantum well layer composed of four layers and the barrier layer composed of three layers are used in the multiple quantum well structure, the number of wells and the number of barriers are not limited. Further, a quaternary mixed crystal represented by InGaAsP or a ternary mixed crystal represented by InGaAs may be used for the quantum well layer. Further, an n-type impurity Si is used as an impurity to be doped simultaneously with Zn. However, other n-type impurities such as Sn, S, and Se, p-type impurities such as Cd, Be, and Mg, and electrically neutral impurities such as Yb are used. The effect of the present invention can be obtained even if an impurity (not p-type or n-type) is used.
【００１０】[0010]
【発明の効果】以上詳細に説明したごとく、本発明の障
壁層へｐ型不純物であるＺnが変調ドーピングされた多
重量子井戸半導体レーザ等に適用される化合物半導体超
格子は、障壁層と量子井戸層とのヘテロ界面近傍の障壁
層側もしくは上記ヘテロ界面近傍の障壁層と量子井戸層
の両層側にｎ型不純物、ｐ型不純物であるＣdまたはＢe
もしくはＭg、または電気的に中性の不純物をドーピン
グしているので、ｐ型不純物であるＺnが障壁層から量
子井戸層へ熱拡散するのを抑制することができ、障壁層
のみに高濃度のｐ型不純物であるＺnの変調ドーピング
を実現することができる。したがって、ｐ型不純物であ
るＺnの熱拡散によるレーザ特性劣化の防止および量子
井戸層内へのｐ型不純物であるＺnの拡散による活性層
での光損失の増大、量子井戸層の結晶特性の劣化を防止
することができ、良好なレーザ特性を有する多重量子井
戸半導体レーザ等が得られる。As described in detail above, a compound semiconductor superlattice applied to a multiple quantum well semiconductor laser or the like in which Zn as a p-type impurity is modulation-doped into a barrier layer according to the present invention includes a barrier layer and a quantum well. Cd or Be, which is an n-type impurity or a p-type impurity,
Alternatively, since Mg or an electrically neutral impurity is doped , Zn which is a p-type impurity can be prevented from thermally diffusing from the barrier layer to the quantum well layer, and only the barrier layer has a high concentration. Modulation doping of Zn which is a p-type impurity can be realized. Therefore, p-type impurity Der
Of the laser characteristics due to thermal diffusion of Zn , increase of light loss in the active layer due to diffusion of Zn which is a p-type impurity into the quantum well layer, and deterioration of crystal characteristics of the quantum well layer. Thus, a multiple quantum well semiconductor laser or the like having good laser characteristics can be obtained.
【図１】本発明の実施例１で例示した多重量子井戸レー
ザ素子活性層の断面構造を示す模式図〔図１（ａ）〕お
よびＺnとＳiのドーピング濃度分布を示す説明図〔図１
（ｂ）〕。FIG. 1 is a schematic diagram illustrating a cross-sectional structure of an active layer of a multiple quantum well laser device exemplified in Example 1 of the present invention (FIG. 1A) and an explanatory diagram illustrating a doping concentration distribution of Zn and Si [FIG.
(B)].
【図２】本発明の実施例２で例示した多重量子井戸レー
ザ素子活性層の断面構造を示す模式図〔図２（ａ）〕お
よびＺnとＳiのドーピング濃度分布を示す説明図〔図２
（ｂ）〕。FIG. 2 is a schematic diagram showing a cross-sectional structure of an active layer of a multiple quantum well laser device exemplified in Embodiment 2 of the present invention (FIG. 2A) and an explanatory diagram showing doping concentration distributions of Zn and Si [FIG.
(B)].
【図３】本発明の実施例３で例示した多重量子井戸レー
ザ素子活性層の断面構造を示す模式図〔図３（ａ）〕お
よびＺnとＳiのドーピング濃度分布を示す説明図〔図３
（ｂ）〕。FIG. 3 is a schematic diagram showing the cross-sectional structure of the active layer of the multiple quantum well laser device exemplified in Embodiment 3 of the present invention (FIG. 3A) and an explanatory diagram showing the doping concentration distribution of Zn and Si [FIG.
(B)].
１…四元混晶ガイド層 ２…四元混晶量子井戸層 ３…四元混晶障壁層 ４…四元混晶バッファ層 ５…ＩnＰ基板 ６…多重量子井戸活性層 REFERENCE SIGNS LIST 1 quaternary mixed crystal guide layer 2 quaternary mixed quantum well layer 3 quaternary mixed barrier layer 4 quaternary mixed buffer layer 5 InP substrate 6 multiple quantum well active layer
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭61−116892（ＪＰ，Ａ) 特開 昭64−42815（ＪＰ，Ａ) 特開 平２−33990（ＪＰ，Ａ) 特開 平２−66986（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01L 21/20 C01B 25/08 C30B 29/68 H01L 29/06 601 H01S 5/343 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-116892 (JP, A) JP-A-64-42815 (JP, A) JP-A-2-33990 (JP, A) JP-A-2- 66986 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) H01L 21/20 C01B 25/08 C30B 29/68 H01L 29/06 601 H01S 5/343
Claims (1)
る四元混晶もしくはＩnＧaＡsで示される三元混晶から
なる量子井戸層と、該量子井戸層よりもバンドギャップ
が大きく、ＩnＰ結晶基板に格子整合し、かつｐ型不純
物であるＺnが添加されたＩnＧaＡsＰで示される四元混
晶からなる障壁層とを交互に積層して構成された単一ま
たは多重量子井戸構造において、上記障壁層と量子井戸
層とのヘテロ界面近傍の障壁層側もしくはヘテロ界面近
傍の障壁層と量子井戸層の両層側に、ｎ型不純物、ｐ型
不純物であるＣdまたはＢeもしくはＭg、または電気的
に中性の不純物を添加してなることを特徴とする化合物
半導体超格子。To 1. A InP crystal substrate, and the quantum well layer made of ternary mixed crystal represented by quaternary mixed crystal or InGaAs represented by InGaAsP, larger band gap than the quantum well layer, an InP crystal substrate matched lattice, and in a single or multiple quantum well structure Zn is configured by alternately laminating a barrier layer composed of a quaternary mixed crystal represented by added InGaAsP a p-type impurity, the barrier layer The n-type impurity and the p-type
A compound semiconductor superlattice characterized by adding Cd, Be, or Mg as an impurity or an electrically neutral impurity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8375592A JP3307669B2 (en) | 1992-04-06 | 1992-04-06 | Compound semiconductor superlattice |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8375592A JP3307669B2 (en) | 1992-04-06 | 1992-04-06 | Compound semiconductor superlattice |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05291133A JPH05291133A (en) | 1993-11-05 |
| JP3307669B2 true JP3307669B2 (en) | 2002-07-24 |
Family
ID=13811368
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8375592A Expired - Fee Related JP3307669B2 (en) | 1992-04-06 | 1992-04-06 | Compound semiconductor superlattice |
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| Country | Link |
|---|---|
| JP (1) | JP3307669B2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5751013A (en) * | 1994-07-21 | 1998-05-12 | Matsushita Electric Industrial Co., Ltd. | Semiconductor light-emitting device and production method thereof |
| TWI234915B (en) * | 2002-11-18 | 2005-06-21 | Pioneer Corp | Semiconductor light-emitting element and method of manufacturing the same |
| KR100765004B1 (en) * | 2004-12-23 | 2007-10-09 | 엘지이노텍 주식회사 | Nitride semiconductor LED and fabrication method thereof |
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1992
- 1992-04-06 JP JP8375592A patent/JP3307669B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05291133A (en) | 1993-11-05 |
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