JPS59172785A - Semiconductor laser - Google Patents
Semiconductor laserInfo
- Publication number
- JPS59172785A JPS59172785A JP4744083A JP4744083A JPS59172785A JP S59172785 A JPS59172785 A JP S59172785A JP 4744083 A JP4744083 A JP 4744083A JP 4744083 A JP4744083 A JP 4744083A JP S59172785 A JPS59172785 A JP S59172785A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- band
- semiconductors
- active layer
- layers
- 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.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
-
- 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
- H01S5/30—Structure or shape of the active region; Materials used for the active region
- H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/37—Non-linear optics for second-harmonic generation
-
- 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
- H01S5/30—Structure or shape of the active region; Materials used for the active region
- H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
- H01S5/3422—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers comprising type-II quantum wells or superlattices
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biophysics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、レーザ加工などに用いる半導体レーザに関し
、特に高出方半導体レーザに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor laser used for laser processing, and particularly to a high output semiconductor laser.
従来の高出力化をめざした半導体レーザの構造として、
活性層内にｐ型不純物を高濃度にドープし、更に端面領
域にｎ型不純物を高濃度にドープして、発振光波長のエ
ネルギーに対して端面領域が透明になる事を意図したい
わゆるウィンドウ型ストライプレーザが知られている。As the structure of conventional semiconductor lasers aiming for high output,
The active layer is doped with p-type impurities at a high concentration, and the end face region is doped with n-type impurities at a high concentration, so that the end face region becomes transparent to the energy of the oscillation light wavelength. Stripe lasers are known.
しかしながら。however.
この従来の方式はＪ活性層内へのｐ型不純物拡散層の濃
度、深さに対して非常に精細な制御が要求され、歩留り
の良い再現性が得られていない。また、活性層に高濃度
の不純物をドープするから、格子欠陥を導入しやすく信
頼性上の問題が指摘される。This conventional method requires extremely precise control over the concentration and depth of the p-type impurity diffusion layer into the J active layer, and does not provide good yield and reproducibility. Furthermore, since the active layer is doped with impurities at a high concentration, lattice defects are likely to be introduced, raising problems in reliability.
本発明の目的は、歩留りよく製造でき高い出力が得られ
る半導体レーザの提供にある。SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor laser that can be manufactured with high yield and provide high output.
本発明による半導体レーザの構成は、電子親和力がそれ
ぞれχ１及びχ２でありバンドギャップがそれぞれＥｇ
ｌ及びＥｇ２である第１及び第２の半導体を積層してな
る超格子構造の活性層と、これら半導体よりバンドギャ
ップが大きいクラッド層とを備え、前記２つの半導体が
χ１〈χ２及びχ１＋Ｅｇ１〈χ、十Ｅｇ２なる関係に
あることを特徴とする。The structure of the semiconductor laser according to the present invention has electron affinities of χ1 and χ2, respectively, and a band gap of Eg.
The active layer has a superlattice structure formed by stacking first and second semiconductors, which are 1 and Eg2, and a cladding layer having a larger band gap than these semiconductors, and the two semiconductors have χ1<χ2 and χ1+Eg1<χ , 10Eg2.
本発明の上記構成を説明する為に、半導体装置ザにおけ
る光学損傷の発生機構および超格子薄膜のバンド構造に
ついて述べる。ＡｔＧａＡｓ ／ＧａＡｓダブルへテロ
半導体レーザについて例をとると通常光出力は数ｍＷの
状態で動作させるが、微細レーザ加工等に於て１００ｍ
Ｗ程度の高出力の要求がされる場合がある。この場合、
光出力密度にして数ＭＷ／７に達っするとミラ一端面の
表面準位での非発光再結合のため活性層内のミラ一端面
領域のキャリアが欠乏した状態になり、フェルミ準位が
下り、実効的なバンドギャップが小さくなる。In order to explain the above structure of the present invention, the mechanism of optical damage generation in a semiconductor device and the band structure of a superlattice thin film will be described. Taking the AtGaAs/GaAs double hetero semiconductor laser as an example, it is normally operated with an optical output of several mW, but in micro laser processing etc.
There are cases where a high output of about W is required. in this case,
When the optical output density reaches several MW/7, the active layer becomes depleted of carriers in the mirror end face region due to non-radiative recombination at the surface level of the mirror end face, and the Fermi level drops. , the effective bandgap becomes smaller.
レーザ発振遷移は帯間発光を利用しているから、活性層
内部結晶で増幅された発振光が端面部の実効的バンドギ
ャップの小さくなった領域に吸収され局所的に温度が上
昇する。通常、半導体結晶は温度が上昇するとバンドギ
ャップが小さくなるから、結晶の光吸収係数が大きくな
り益々光エネルギーはミラ一端面領域へ吸収されていく
様になる。Since the laser oscillation transition utilizes interband light emission, the oscillation light amplified by the internal crystal of the active layer is absorbed in the region where the effective band gap of the end face is reduced, causing a local temperature rise. Normally, as the temperature of a semiconductor crystal rises, the band gap becomes smaller, so the light absorption coefficient of the crystal increases, and more and more light energy is absorbed into one end face region of the mirror.
この様な正帰還がかかるから、端面結晶の一部はレーザ
発振の横モード分布において光強度の大きい箇所で結晶
融点以上に達っする事が実験的にも確認されている。破
壊された端面結晶に発生した格子欠陥もまた光吸収箇所
となるから１局所的な溶融領域が結晶内部にも生ずる。It has been experimentally confirmed that due to such positive feedback, a portion of the end face crystal reaches a temperature higher than the crystal melting point at a location where the light intensity is large in the transverse mode distribution of laser oscillation. Since the lattice defects generated in the destroyed end face crystal also become light absorption sites, a local melting region is also generated inside the crystal.
この溶融−城が冷却された箇所に格子欠陥が残され、こ
の様な非発光領域が大きくなるとレーザ発振に必要な利
得が得られなくなり発振停止に到る。以上のミラ一端面
領域における光吸収の説明から明らかなように１発振光
の光エネルギーを活性層を形成する結晶のバンドギャッ
プ以下にすれば光学損傷の起きない事がわかる。この様
な発振光を得る方法を以下に述べる。Lattice defects are left behind at locations where the molten castle has cooled, and when such non-emitting regions become large, the gain necessary for laser oscillation cannot be obtained and oscillation stops. As is clear from the above explanation of light absorption in one end face region of the mirror, it can be seen that optical damage does not occur if the optical energy of one oscillation light is made equal to or less than the band gap of the crystal forming the active layer. A method for obtaining such oscillation light will be described below.
最近極薄膜の成長がＭ Ｂ Ｅ （Ｍｏ１ｅｃｕｌａｒ
ＢｅａｍＥｐｉｔａｘｙ ）法により可能になり、極
薄膜へテロ構造を繰り返し成長する事により超格子構造
が製作されている。適当な電子親和力とバンドギヤ・ノ
ブをもつ半導体を組み合せる事により第１図の様なバン
ド構造をもつ超格子を得る事が可能である。Recently, the growth of ultra-thin films has become popular.
This is made possible by the beam epitaxy (BeamEpitaxy) method, and a superlattice structure is fabricated by repeatedly growing an extremely thin film heterostructure. By combining semiconductors with appropriate electron affinity and band gear knobs, it is possible to obtain a superlattice with a band structure as shown in Figure 1.
即ち、本図のバンド構造の超格子では、層Ｉの電子親和
力χ１が層■の電子親和力χ２よりも小さいから、層Ｉ
の伝導帯は層■の伝導帯よりも高エネルギー位置にある
。また、層ＩのバンドギャップＢｇ１と層■のバンドギ
ャップＥｇ２とがχ１＋Ｂｇ１（χ２＋Ｅｇｚの関係に
あれば、層Ｉの価電子帯の位置は層■の価電子帯よりも
高エネルギー位置にある。この様なバンド構造をもつ超
格子においては、電子は層■に閉じ込められ、一方正孔
は層Ｉに閉じ込められる。この場合、電子のドブロイ波
長以下に層厚を薄くしていくと（（１００人）、井戸型
ポテンシャルの量子効果があられれ、電子および正孔は
それぞれのポテンシャル内に離散準位を形成し、それぞ
れの波動関数は第１図に示した様に隣の層へのしみ出し
成分を持つ様になる。That is, in the superlattice with the band structure shown in this figure, since the electron affinity χ1 of layer I is smaller than the electron affinity χ2 of layer
The conduction band of is at a higher energy position than the conduction band of layer ■. Furthermore, if the band gap Bg1 of layer I and the band gap Eg2 of layer (2) have a relationship of χ1 + Bg1 (χ2 + Egz), then the position of the valence band of layer I is at a higher energy position than that of the valence band of layer (2). In a superlattice with a similar band structure, electrons are confined in layer I, while holes are confined in layer I. ), due to the quantum effect of the well-type potential, electrons and holes form discrete levels within their respective potentials, and each wave function is a component that seeps into the adjacent layer as shown in Figure 1. It becomes like having.
この様な情況では層Ｉのポテンシャルに存在スる正孔と
層Ｈのポテンシャルに存在する電子が再結合する事によ
る発光がみられ、その光エネルギーＥｇ″は層Ｉのバン
ドギャップＥｇｘおよび層■のバンドギャップＥｇ２の
どちらよりも低エネルギーになる事が第１図から理解さ
れる。In such a situation, light emission is observed due to the recombination of holes existing in the potential of layer I and electrons existing in the potential of layer H, and the light energy Eg'' is equal to the band gap Egx of layer I and the layer It is understood from FIG. 1 that the energy is lower than either of the band gaps Eg2.
従ってこの様な構造の活性層をもたせれば、活性層のそ
れぞれの結晶のバンドギャップより低エネルギーの発光
を得る事が出来、光学損傷予防の目的を達成する事が出
来る。電子および正孔の系外への拡散を防ぐためには超
格子活性層の両側を更にバンドギャップの大きい半導体
層（クラッド層）で挾む事により実現される。Therefore, by providing an active layer with such a structure, it is possible to obtain light emission with energy lower than the band gap of each crystal in the active layer, and the purpose of preventing optical damage can be achieved. In order to prevent electrons and holes from diffusing out of the system, the superlattice active layer is sandwiched between semiconductor layers (cladding layers) with a large band gap on both sides.
次に本発明の一実施例の構造を示す第２図を参照して、
本発明を一層詳細に説明する。ｎ型ＧａＡｓ基板１上に
ｎ聖人ｔｏ、３０ａｏ、ｔ Ａｓクラッド層２を約３μ
ｍ成長させた後、活性層３を成長させる。活性層を構成
する超格子の組み合せはＧａＡｓ／ Ａｔ８ ｂを用い
た。超格子構造は層ＩがＡｚｓｂ（Ｚ １ ＝ ３．６
ｅＶ、 Ｂｇｌ ＝ １．６ ｅＶ ）、層■がＧａ
Ａｓ（ｚ２＝４．１ｅＶ、Ｅｇｚ＝１．４ｅＶ）から成
り、ＡｔＳ ｂ層を５０人Ｇ ａ Ａ ｓ層を５０人の
繰り返しで１５周期、合計〜１５００人の活性層厚であ
る。Next, referring to FIG. 2 showing the structure of an embodiment of the present invention,
The invention will now be described in more detail. On an n-type GaAs substrate 1, an n-type GaAs cladding layer 2 with a thickness of about 3μ is formed.
After growing the active layer 3, the active layer 3 is grown. GaAs/At8b was used as the superlattice combination constituting the active layer. In the superlattice structure, layer I is Azsb (Z 1 = 3.6
eV, Bgl = 1.6 eV), layer ■ is Ga
It consists of As (z2 = 4.1 eV, Egz = 1.4 eV), and the active layer thickness is 15 cycles with 50 people repeating the AtS b layer and 50 people repeating the Ga As layer, with a total active layer thickness of ~1500 people.
活性層３のドーピングは行なわない。更にｐ型ｋｌｆ−
ｏ、ｓ Ｇａｏ、ｙ Ａｓクラッド層４を約３μｍ成長
させた。次に、クラッド層４上に５ｉｎ２膜５で巾１０
μｍのストライプ状の窓を設け、電流狭窄を行なってい
る。ｐ壓オーミック電極６としてはＡｕ−Ｚｎを用いで
ある。また、基板１ ｉｌｌのｎ型オーミック電極７と
してはＡｕ−Ｇｅを用いた。この様圧して形成されたウ
ェハーから弁開により結晶端面をミラー面とする半導体
レーザを製作した。The active layer 3 is not doped. Furthermore, p-type klf-
o, s Gao, y As cladding layer 4 was grown to a thickness of about 3 μm. Next, on the cladding layer 4, a 5in2 film 5 with a width of 10
A striped window of μm size is provided to perform current confinement. The p-ohmic electrode 6 is made of Au-Zn. Moreover, Au-Ge was used as the n-type ohmic electrode 7 of the substrate 1ill. From the wafer formed under this pressure, a semiconductor laser was fabricated with the crystal end face being a mirror surface by opening the valve.
この実施例の半導体レーザは、光出力が １００ｍＷ
（光出力密度にして７ ＭＷ／、ｆｆｌ ）を超えても
光学損傷を起さないし、もちろん超格子特有の矩型状の
状態密度のため発振閾値の温度依存性が非常に少なく、
室温ＣＷ発振閾値も１００ｍＡ以下のものが容易に得ら
れる。The semiconductor laser of this example has an optical output of 100 mW.
(7 MW/, ffl in terms of optical output density) does not cause optical damage, and of course, due to the rectangular density of states unique to superlattices, the temperature dependence of the oscillation threshold is very small.
A room temperature CW oscillation threshold of 100 mA or less can be easily obtained.
以上詳述したように１本発明によれば１歩留りよく製造
できる高出力の半導体レーザか提供できる。As detailed above, according to the present invention, it is possible to provide a high-output semiconductor laser that can be manufactured with good yield.
第１図は超格子バンド構造の説明図、第２図は本発明の
一実施例の構造図である。
１・曲・ｎ型Ｇ ａ Ａ ｓ基板％２・・曲ｎ型Ａｔｏ
、ｓ Ｇａ０−７ Ａ ｓクラッド層、３ ・−−−−
−ＧａＡｓ／ＡＩＳ ｂ超格子活性層、４・・・・・・
ｐ型ｋｌｏ、ｓ Ｇａｏ、ｙ Ａｓクラッド層。
５・・・・・・電流狭窄用８ｉ０．膜、６・・・・・・
ｐ型電極、７・・・・・・ｎ型電極。
警１ 口
層１ 層丁 層１ 層
半２釦
／
□翼γ坪楳
且
、／にFIG. 1 is an explanatory diagram of a superlattice band structure, and FIG. 2 is a structural diagram of an embodiment of the present invention. 1. Curved n-type Ga As substrate %2... Curved n-type Ato
, s Ga0-7 A s cladding layer, 3 ・----
-GaAs/AIS b superlattice active layer, 4...
p-type klo, s Gao, y As cladding layer. 5...8i0 for current confinement. Membrane, 6...
p-type electrode, 7...n-type electrode. Guard 1 Mouth layer 1 Layer 1 Layer and a half 2 buttons / □ Wings γ tsubo and / ni
Claims (1)
プがそれぞれＢｇｌ及びＥｇ２である第１及び第２の半
導体を積層してなる超格子構造の活性層と、これら半導
体よりバンドギャップが大きいクラッド層とを備え、前
記２つの半導体がχｌ〈χ２及びχを十Ｂｇｌ＜χ２十
Ｅｇ＋なる関係にあることを特徴とする半導体レーザ。An active layer having a superlattice structure formed by stacking first and second semiconductors having electron affinities of χ1 and χ, respectively, and band gaps of Bgl and Eg2, respectively, and a cladding layer having a larger band gap than these semiconductors. A semiconductor laser, characterized in that the two semiconductors have a relationship such that χl<χ2 and χ10Bgl<χ20Eg+.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4744083A JPS59172785A (en) | 1983-03-22 | 1983-03-22 | Semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4744083A JPS59172785A (en) | 1983-03-22 | 1983-03-22 | Semiconductor laser |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59172785A true JPS59172785A (en) | 1984-09-29 |
| JPH0467353B2 JPH0467353B2 (en) | 1992-10-28 |
Family
ID=12775202
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4744083A Granted JPS59172785A (en) | 1983-03-22 | 1983-03-22 | Semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59172785A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61102084A (en) * | 1984-10-25 | 1986-05-20 | Nec Corp | Semiconductor laser |
| JPS61218192A (en) * | 1985-03-25 | 1986-09-27 | Hitachi Ltd | Semiconductor light emitting element |
| JPH0715093A (en) * | 1993-06-25 | 1995-01-17 | Nec Corp | Optical semiconductor element |
| WO1995026585A1 (en) * | 1994-03-25 | 1995-10-05 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Quantum-layer structure |
-
1983
- 1983-03-22 JP JP4744083A patent/JPS59172785A/en active Granted
Non-Patent Citations (1)
| Title |
|---|
| APPLED PHYSICS LETTERS=1977 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61102084A (en) * | 1984-10-25 | 1986-05-20 | Nec Corp | Semiconductor laser |
| JPS61218192A (en) * | 1985-03-25 | 1986-09-27 | Hitachi Ltd | Semiconductor light emitting element |
| JPH0712100B2 (en) * | 1985-03-25 | 1995-02-08 | 株式会社日立製作所 | Semiconductor light emitting element |
| JPH0715093A (en) * | 1993-06-25 | 1995-01-17 | Nec Corp | Optical semiconductor element |
| WO1995026585A1 (en) * | 1994-03-25 | 1995-10-05 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Quantum-layer structure |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0467353B2 (en) | 1992-10-28 |
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