JPH07191289A - Waveguide type inclined multiple quantum well optical control element - Google Patents

Waveguide type inclined multiple quantum well optical control element

Info

Publication number
JPH07191289A
JPH07191289A JP5333259A JP33325993A JPH07191289A JP H07191289 A JPH07191289 A JP H07191289A JP 5333259 A JP5333259 A JP 5333259A JP 33325993 A JP33325993 A JP 33325993A JP H07191289 A JPH07191289 A JP H07191289A
Authority
JP
Japan
Prior art keywords
quantum well
layer
electric field
semiconductor layer
multiple quantum
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.)
Pending
Application number
JP5333259A
Other languages
Japanese (ja)
Inventor
Koichi Wakita
紘一 脇田
Takayuki Yamanaka
孝之 山中
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Telegraph and Telephone Corp
Original Assignee
Nippon Telegraph and Telephone Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to JP5333259A priority Critical patent/JPH07191289A/en
Publication of JPH07191289A publication Critical patent/JPH07191289A/en
Pending legal-status Critical Current

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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
    • 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
    • G02F1/01—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 for the control of the intensity, phase, polarisation or colour 
    • G02F1/015—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 for the control of the intensity, phase, polarisation or colour  based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction
    • G02F1/017—Structures with periodic or quasi periodic potential variation, e.g. superlattices, quantum wells
    • G02F1/01725—Non-rectangular quantum well structures, e.g. graded or stepped quantum wells
    • 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
    • G02F1/01—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 for the control of the intensity, phase, polarisation or colour 
    • G02F1/015—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 for the control of the intensity, phase, polarisation or colour  based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction
    • G02F1/017—Structures with periodic or quasi periodic potential variation, e.g. superlattices, quantum wells
    • G02F1/01725—Non-rectangular quantum well structures, e.g. graded or stepped quantum wells
    • G02F1/0175—Non-rectangular quantum well structures, e.g. graded or stepped quantum wells with a spatially varied well profile, e.g. graded or stepped quantum wells

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biophysics (AREA)
  • Crystallography & Structural Chemistry (AREA)

Abstract

PURPOSE:To obtain an optical control element which operates on a low voltage, has a broad band width, is low in insertion loss, has high performance and is small in size by adopting compsns. obtd. by inclining the band gap energy of a barrier layer adjacent to a quantum well in its thickness direction. CONSTITUTION:An InP layer 2 is grown on an n-InP substrate 1 and further, a multiple quantum well structure consisting of InGaAsP layers 3, 4, InGaAsP quantum well layer 5 and In(GaAs)P barrier layer 6 respectively having prescribed compsns. and InGaAsP layers 7, 8, InP layer 9 and InGaAs cap layer 10 are successively grown thereon. Next, electrodes 11, 12 are formed on the P and N side. The well layer 5 and the barrier layer 6 are so arranged and composed that the angle of inclination of their band gap energy distribution is decreased by an externally impressed electric field. These layers are so formed that electrons are confined even at the time of impressing the electric field to the quantum well. P and N impurity regions 13, 14 are so formed that the thickness of the unoped region held therebetween is 500 to 1500nm.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、光変調や光スイッチ等
を行う光デバイスにかかり、特に超高速で低電圧駆動可
能な光結合効率の高い高性能かつ小形の光制御素子に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device for performing optical modulation, optical switching, and the like, and more particularly to a high-performance and small-sized light control element which has a high optical coupling efficiency and can be driven at a very high speed and a low voltage. .

【０００２】[0002]

【従来の技術】近年の結晶成長技術の進展により良好な
特性を持つ半導体多重量子井戸（Ｍｕｌｔｉｐｌｅ Ｑ
ｕａｎｔｕｍ Ｗｅｌｌ：以下ＭＱＷと略す）構造が作
製され、その量子サイズ効果を利用することによって従
来のバルクを用いた素子よりも高効率で小形の光変調器
や光スイッチ等が得られることが報告されている（例え
ば電子情報通信学会論文誌Ｃ−１，Ｊ７４−Ｃ−１巻、
ｐｐ．４１４−４２０）。これまで、光送用に光ファイ
バの伝送損失の少ない波長域で動作するＭＱＷ構造とし
ては、ＩｎＧａＡｓ（Ｐ）／ＩｎＧａＡｓＰとＩｎＧａ
Ａｓ／ＩｎＡｌＡｓの組み合わせが使われてきた。Ｉｎ
ＧａＡｓ／ＩｎＡｌＡｓ系は、量子井戸としての効果は
大きいものの、他方に比べてＡｌなどの化学的に活性な
元素を含んでいるために製造しにくいという欠点があ
る。さらに、この材料を用いたレーザにおいても特性は
十分でなく、レーザと変調器との集積化も技術的に困難
な点が多かった。一方、ＩｎＧａＡｓ（Ｐ）／ＩｎＧａ
ＡｓＰ系は、レーザで既に実績があり、また、レーザと
のモノリシック集積化も比較的容易である。しかし、こ
の系では、図１に示されるように、エネルギバンドでの
価電子帯におけるバンドオフセットΔＥｖが大きく、逆
に伝導帯バンドオフセットΔＥｃが小さいために、電子
の閉じ込めは弱く、電界印加で容易に量子サイズ効果が
崩れてしまう問題がある。さらに、正孔の質量が電子に
比べてはるかに重いこともあって、高光入力で正孔の蓄
積を生じて周波数応答性が劣化するなど、量子井戸構造
の特徴が生かせないという問題があった。すなわち、量
子効果を際だたせるためには、大きなΔＥｃを与えるＩ
ｎＰを用いて厚い障壁層とすれば、充分に電子の閉じ込
めができるが、一方、光吸収に伴って発生する正孔にと
っては閉じ込めが強すぎて障壁層を越えられないため、
正孔が井戸層に蓄積されて、外部電界をシールドし、そ
の結果、変調特性を劣化させてしまう。このため、量子
効果をある程度犠牲にすることによって、前記の問題を
回避することが行われていた。2. Description of the Related Art A semiconductor multiple quantum well (Multiple Q) having good characteristics has been developed by the recent progress of crystal growth technology.
It has been reported that a small optical modulator, an optical switch, etc. can be obtained with higher efficiency than a device using a conventional bulk by utilizing the quantum size effect. (For example, IEICE Transactions C-1, J74-C-1,
pp. 414-420). Up to now, InGaAs (P) / InGaAsP and InGa have been used as the MQW structure that operates in a wavelength range in which the transmission loss of the optical fiber is small for optical transmission.
The As / InAlAs combination has been used. In
Although the GaAs / InAlAs system has a great effect as a quantum well, it has a drawback that it is difficult to manufacture because it contains a chemically active element such as Al as compared with the other. Further, the characteristics of the laser using this material are not sufficient, and there are many technical difficulties in integrating the laser and the modulator. On the other hand, InGaAs (P) / InGa
The AsP system has already been used as a laser, and monolithic integration with a laser is relatively easy. However, in this system, as shown in FIG. 1, since the band offset ΔEv in the valence band in the energy band is large and the conduction band offset ΔEc is small on the contrary, the electron confinement is weak and it is easy to apply an electric field. There is a problem that the quantum size effect collapses. Furthermore, since the mass of holes is much heavier than that of electrons, there was a problem that the characteristics of the quantum well structure could not be utilized, such as the accumulation of holes at high light input and the deterioration of frequency response. . That is, in order to emphasize the quantum effect, I that gives a large ΔEc
If nP is used to form a thick barrier layer, electrons can be sufficiently confined. On the other hand, holes generated due to light absorption are too confined and cannot cross the barrier layer.
The holes are accumulated in the well layer and shield the external electric field, resulting in deterioration of the modulation characteristic. Therefore, the above problem has been avoided by sacrificing the quantum effect to some extent.

【０００３】[0003]

【発明が解決しようとする課題】本発明の課題は、ＭＱ
Ｗ層に垂直に電界を印加したときの障壁層のポテンシャ
ル形状を電子が漏れにくいようにして、電界による吸収
係数変化を大きくすることにある。これにより、ＩｎＧ
ａＡｓ（Ｐ）／ＩｎＧａＡｓＰ系ＭＱＷ構造に代表され
る量子井戸を用いて作製された変調器・スイッチ等に固
有の前記従来の問題を解決して、低電圧で動作し、広帯
域幅を持ち低挿入損失である高性能で小形の光制御素子
を実現するにある。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The potential shape of the barrier layer when an electric field is applied perpendicularly to the W layer is to prevent electrons from leaking so that the change in absorption coefficient due to the electric field is increased. As a result, InG
Solving the above-mentioned conventional problems peculiar to modulators / switches manufactured by using a quantum well typified by an aAs (P) / InGaAsP-based MQW structure, operating at a low voltage, having a wide bandwidth and low insertion It is to realize a high-performance and small-sized light control element that is a loss.

【０００４】[0004]

【課題を解決するための手段】この光制御素子を実現す
るために、厚さがボーア半径より薄い第１のバンドギャ
ップエネルギを持つ第１の半導体層と、これより大きな
バンドギャップエネルギを持つ第２の半導体層とからな
る多重量子井戸構造をコア層とする導波形光半導体素子
において、前記第２の半導体層のバンドギャップエネル
ギをその厚さ方向に傾斜させた組成とする。また、前記
コア層の周りを、前記第２の半導体のうち最大のバンド
ギャップエネルギと等しいかこれより大きなバンドギャ
ップエネルギを持ち、かつ前記中心コアより離れるに従
って順次バンドギャップエネルギの増加する半導体クラ
ッド層で挟んだ屈折率傾斜型分離光閉じ込め多重量子井
戸（ＧＲＩＮ−ＳＣＨ−ＭＱＷ）導波構造を持たせる。
あるいは、コア層を囲む半導体クラッド層を複数個設
け、コア層から離れるに従って、バンドギャップエネル
ギの大きなクラッド層が順に並ぶように配置する。さら
に、該導波構造の両側をたがいに一方を他方とその導電
形が異なるように不純物を添加して、外部から前記導波
構造に垂直に電圧を印加できるようにし、かつ前記第２
の半導体層の傾斜したバンドギャップエネルギ分布を、
外部印加電界で傾斜の角度が減少するように配置した構
成とする。In order to realize this light control element, a first semiconductor layer having a first bandgap energy having a thickness smaller than a Bohr radius and a first semiconductor layer having a bandgap energy larger than the first semiconductor layer have a thickness smaller than the Bohr radius. In a waveguide type optical semiconductor device having a core layer of a multiple quantum well structure composed of two semiconductor layers, the composition is such that the band gap energy of the second semiconductor layer is inclined in the thickness direction. Further, a semiconductor clad layer having a bandgap energy equal to or larger than the maximum bandgap energy of the second semiconductor around the core layer, and the bandgap energy gradually increases as the distance from the central core increases. It has a graded refractive index split optical confinement multiple quantum well (GRIN-SCH-MQW) waveguide structure sandwiched between.
Alternatively, a plurality of semiconductor clad layers surrounding the core layer are provided, and the clad layers having a larger band gap energy are arranged in order as the clad layers are separated from the core layer. Further, impurities are added to each other on both sides of the waveguide structure so that one of them has a different conductivity type from the other so that a voltage can be applied perpendicularly to the waveguide structure from the outside.
The inclined bandgap energy distribution of the semiconductor layer of
The configuration is such that the angle of inclination is reduced by the externally applied electric field.

【０００５】[0005]

【作用】本発明の構造では、屈折率傾斜型あるいは複数
のクラッド層を持つ分離閉じ込め多重量子井戸層を導波
構造に用いており、かつ、量子井戸に隣接する障壁層の
バンドギャップエネルギをその厚さ方向に傾斜させた組
成とし、そのバンドギャップエネルギ分布を外部印加電
界で傾斜の角度が減少するように配置した構成としてい
るため、電界が印加されても障壁層を越えて電子が漏れ
ることなく、大きな吸収係数変化、屈折率変化が得られ
る。さらに層に垂直に電圧を印加できるようにするため
に設けられたＰ，Ｎの不純物の添加層は、その内部の多
重量子井戸層より屈折率、バンドギャップエネルギは各
々小さく、あるいは大きくなっており、かつ、その厚さ
も５０ｎｍ以上あるため、光の伝搬損失は少なく、素子
の容量は大きくならず、高速応答が可能となる。In the structure of the present invention, the split confinement multiple quantum well layer having the graded index type or a plurality of cladding layers is used for the waveguide structure, and the bandgap energy of the barrier layer adjacent to the quantum well is determined by Since the composition is graded in the thickness direction and the bandgap energy distribution is arranged so that the angle of the gradient is reduced by an externally applied electric field, electrons will leak past the barrier layer even when an electric field is applied. However, a large change in absorption coefficient and a large change in refractive index can be obtained. Further, the P and N impurity-added layers provided to enable the voltage to be applied perpendicularly to the layers have a refractive index and a band gap energy which are smaller or larger than those of the multi-quantum well layer inside thereof. Moreover, since its thickness is 50 nm or more, the propagation loss of light is small, the capacitance of the element does not increase, and high-speed response is possible.

【０００６】[0006]

【実施例】以下、本発明の実施例を図面を参照して説明
する。Embodiments of the present invention will be described below with reference to the drawings.

【０００７】本発明では、従来の問題を解決すべく、Ｉ
ｎＧａＡｓ（Ｐ）／ＩｎＧａＡｓＰにおける量子効果を
計算機および実験との対比によって改めて定量的に解析
し、その問題の機構を解明して対策を講じた。図２、３
は、ＩｎＧａＡｓ（Ｐ）／ＩｎＧａＡｓＰ単一量子井戸
構造に対して層に垂直な電界を加えたとき、その吸収係
数がどのように変化するかを理論的に計算するためのモ
デルと計算結果を示したものである。図２は、井戸を挾
む障壁層にも電界がかかって、（ｂ）図に示すように、
そのポテンシャルの形状が電界方向に傾斜しており、そ
のため電子の波動関数が障壁層を漏れ出ている場合を示
している。また、図３は、井戸を挾む障壁層に電界がか
からず、（ｂ）図に示すように、そのポテンシャルの形
状が変化しない場合を示す。量子井戸構造では吸収スペ
クトル中に励起子吸収と呼ばれる鋭い吸収線が室温でも
存在し、これが電界印加によって図３の場合では、その
半値幅をやや広げながら長波長側にシフトする。これに
対して、図２の場合では、ピーク位置はシフトするもの
の、高電界でその半値幅を大きく広げ、その強度は急激
に小さくなる。これまでは、計算の簡単な図３のモデル
しか考慮されず、実験と理論との大幅な違いが問題にな
っていた。本出願者らはモデル図２に基づいて改めて計
算し、実験事実と計算結果の良く合うことが確認でき
た。そして、この両者の差異は、量子井戸そのものは同
じでも、これを囲む障壁層の構成によって生ずることが
明かとなった。すなわち、前記従来の多重量子井戸構造
では、障壁層にＩｎＧａＡｓＰを用いると、ヘテロ接合
でのエネルギギャップ差が小さいため、電界印加に伴
い、必然的に井戸を挾む障壁層にも電界がかって、その
ポテンシャルの形状が三角形になり、電子の波動関数が
障壁層を漏れ出て、図２に示す結果となる。そこで図３
に示された構造にすることができれば、電界効果は効率
よく働き、これまでの問題は解決するはずである。この
電界加による吸収線の広がる効果は、量子井戸層と障壁
層とのエネルギバンドオフセットの大きさ及びその形状
に依存しており、正孔に比べてその有効質量の小さい電
子に対する障壁の高さΔＥｃが小さいときに、特に顕著
に出現する。従って、ΔＥｃの大きい組み合わせを選べ
ばよいことになるが、ＩｎＧａＡｓ（Ｐ）／ＩｎＧａＡ
ｓＰの組み合せではもともと小さく、ＩｎＰ基板と格子
整合する条件では最大でも０．２３ｅＶ（ＩｎＧａＡｓ
とＩｎＰの組み合わせ）である。In the present invention, in order to solve the conventional problems, I
The quantum effect in nGaAs (P) / InGaAsP was quantitatively analyzed again by comparison with a computer and an experiment, the mechanism of the problem was clarified, and countermeasures were taken. 2, 3
Shows a model and a calculation result for theoretically calculating how the absorption coefficient changes when an electric field perpendicular to the layer is applied to the InGaAs (P) / InGaAsP single quantum well structure. It is a thing. In FIG. 2, an electric field is applied to the barrier layer that sandwiches the well, and as shown in FIG.
The shape of the potential is inclined in the direction of the electric field, so that the wave function of the electron leaks from the barrier layer. Further, FIG. 3 shows a case where an electric field is not applied to the barrier layer that sandwiches the well, and the shape of the potential does not change as shown in FIG. In the quantum well structure, a sharp absorption line called exciton absorption exists in the absorption spectrum even at room temperature, and in the case of FIG. 3, this shifts to the long wavelength side while broadening the half-value width a little by applying an electric field. On the other hand, in the case of FIG. 2, although the peak position shifts, its half-value width is greatly widened by a high electric field, and its intensity sharply decreases. Until now, only the model of FIG. 3 which has a simple calculation was considered, and a big difference between the experiment and the theory had been a problem. The present applicants calculated again based on the model FIG. 2 and confirmed that the experimental facts and the calculation results are in good agreement. Then, it was revealed that the difference between the two is caused by the structure of the barrier layer surrounding the quantum well even though the quantum well itself is the same. That is, in the conventional multi-quantum well structure, when InGaAsP is used for the barrier layer, the difference in energy gap at the heterojunction is small, so that an electric field is inevitably applied to the barrier layer sandwiching the well as an electric field is applied. The shape of the potential becomes a triangle, the wave function of the electron leaks out of the barrier layer, and the result shown in FIG. 2 is obtained. So Fig. 3
If the structure shown in (1) can be obtained, the electric field effect will work efficiently and the problems so far should be solved. The effect of spreading the absorption line due to the application of the electric field depends on the size and shape of the energy band offset between the quantum well layer and the barrier layer, and the height of the barrier for electrons whose effective mass is smaller than that of holes. It appears particularly remarkably when ΔEc is small. Therefore, it is sufficient to select a combination with a large ΔEc. InGaAs (P) / InGaA
The sP combination is originally small, and the maximum is 0.23 eV (InGaAs
And InP)).

【０００８】他方、電界印加によるコア層をとりかこむ
ＳＣＨ層のポテンシャル形状の変化を防止または減少さ
せて、障壁層としての働きを保持できれば、前記の問題
は緩和する（図４（ａ），（ｂ）参照）が、これは単一
の量子井戸にしか適用できない。大きな消光比を得るに
は多重化して光の閉じ込めを向上する必要があるが、井
戸と井戸の間の障壁層にも外部電界がかかり、前記の問
題が顕著に現れてしまう。On the other hand, if the change in the potential shape of the SCH layer surrounding the core layer due to the application of an electric field can be prevented or reduced and the function as a barrier layer can be maintained, the above problems can be alleviated (FIG. 4 (a), ( See b)), but this is only applicable to a single quantum well. In order to obtain a large extinction ratio, it is necessary to multiplex and improve the light confinement, but the external electric field is also applied to the barrier layer between the wells, so that the above-mentioned problem becomes remarkable.

【０００９】本発明では、電界印加で励起子吸収がなく
ならないで吸収係数変化の大きくなるように図５，図６
および図７の構成を採用した。In the present invention, the exciton absorption is not eliminated by the application of an electric field, and the change in the absorption coefficient is increased so as to increase the absorption coefficient.
And the configuration of FIG. 7 is adopted.

【００１０】（実施例１）図５は、本発明の実施例であ
る導波形分離光閉じ込め傾斜多重量子井戸光制御素子を
示す。ｎ−ＩｎＰ基板１の上にＭＯＶＰＥ（有機金属気
相成長法）またはＭＢＥ（分子線エピタキシャル法）に
より、厚さ０．３μｍのＩｎＰ層２を成長させ、図６に
詳しく示したように、厚さ０．１μｍのＩｎＧａＡｓＰ
層３（組成はフォトルミネッセンス波長にして１．０５
μｍ）、厚さ０．１μｍのＩｎＧａＡｓＰ層４（組成は
フォトルミネッセンス波長にして１．１μｍ）、厚さ１
０ｎｍのＩｎＧａＡｓ層を井戸層５、厚さ５ｎｍのＩｎ
（ＧａＡｓ）Ｐを障壁層６とする６周期の多重量子井戸
構造の上に厚さ０．１μｍのＩｎＧａＡｓＰ層７（組成
はフォトルミネッセンス波長にして１．０５μｍ）、厚
さ０．１μｍのＩｎＧａＡｓＰ層８（組成はフォトルミ
ネッセンス波長にして１．０５μｍ）、厚さ２μｍのＩ
ｎＰ層９、厚さ０．５μｍのＩｎＧａＡｓキャップ層１
０を、順に成長させた。次に、所定のフォトワーク、エ
ッチング、蒸着操作を繰り返して、図５に示すように、
ＰおよびＮ側に電極１１，１２を形成する。ＩｎＧａＡ
ｓＰ量子井戸層５とＩｎ（ＧａＡｓ）Ｐ障壁層６とは、
図８に示すような伝導帯エネルギバンドでのバンドオフ
セットを持つようになっており、そのバンドギャップエ
ネルギ分布の外部印加電界で傾斜の角度が減少するよう
に配置した構成としているため、電界が印加されても障
壁層を越えて電子が漏れることなく、電子を量子井戸に
電界印加時にも閉じ込められるようになっている。従っ
て、通常の多重量子井戸構造でみられる薄い障壁層を介
して電子がこれを通り抜けることが少ない。ＰおよびＮ
不純物領域１３，１４はその間に挟まれるノンドープ領
域の厚さを５００−１５００ｎｍとなるようにしてい
る。(Embodiment 1) FIG. 5 shows a waveguide type split light confined multiple quantum well optical control device according to an embodiment of the present invention. An InP layer 2 having a thickness of 0.3 μm is grown on the n-InP substrate 1 by MOVPE (Metal Organic Chemical Vapor Deposition) or MBE (Molecular Beam Epitaxial Method), and as shown in detail in FIG. 0.1 μm InGaAsP
Layer 3 (Composition: 1.05 for photoluminescence wavelength)
μm), an InGaAsP layer 4 having a thickness of 0.1 μm (composition is 1.1 μm in terms of photoluminescence wavelength), and a thickness of 1
A 0 nm InGaAs layer is a well layer 5, and a 5 nm thick In
An InGaAsP layer 7 having a thickness of 0.1 μm (the composition is 1.05 μm in terms of photoluminescence wavelength) and an InGaAsP layer having a thickness of 0.1 μm on a 6-period multiple quantum well structure using (GaAs) P as a barrier layer 6. 8 (composition is 1.05 μm in terms of photoluminescence wavelength) and I having a thickness of 2 μm
nP layer 9, 0.5 μm thick InGaAs cap layer 1
0 was grown in sequence. Next, by repeating the predetermined photowork, etching, and vapor deposition operations, as shown in FIG.
Electrodes 11 and 12 are formed on the P and N sides. InGaA
The sP quantum well layer 5 and the In (GaAs) P barrier layer 6 are
As shown in FIG. 8, it has a band offset in the conduction band energy band and is arranged so that the angle of inclination is reduced by the externally applied electric field of the band gap energy distribution. Even if this happens, the electrons do not leak beyond the barrier layer and are confined in the quantum well even when an electric field is applied. Therefore, electrons are less likely to pass through the thin barrier layer found in the usual multiple quantum well structure. P and N
The impurity regions 13 and 14 are arranged such that the thickness of the non-doped region sandwiched therebetween is 500-1500 nm.

【００１１】（実施例２）図７は、本発明の第２の実施
例を示すもので、クラッド層を除く他の構成は図５、６
と同じ構成になっている。クラッド層１５は、ｎ−Ｉｎ
Ｐ層の上からＩｎＧａＡｓＰ／Ｉｎ（ＧａＡｓ）Ｐ多重
量子井戸層までＩｎＧａＡｓＰ混晶で、その組成はフォ
トルミネッセンス波長にして１．０μｍから１．１μｍ
であり、図７に示すように、コアを中心に直線状に傾斜
しており、かつ、ＩｎＰ基板に格子整合している。Ｉｎ
ＧａＡｓＰ量子井戸層は必ずしもＩｎＰ基板に格子整合
している必要はなく、本実施例では圧縮歪が１．４％入
っている。(Embodiment 2) FIG. 7 shows a second embodiment of the present invention. Other structures except the cladding layer are shown in FIGS.
It has the same structure as. The cladding layer 15 is n-In
InGaAsP mixed crystal from the P layer to the InGaAsP / In (GaAs) P multiple quantum well layer, the composition of which is a photoluminescence wavelength of 1.0 μm to 1.1 μm
As shown in FIG. 7, the core is linearly inclined with respect to the core and lattice-matched with the InP substrate. In
The GaAsP quantum well layer does not necessarily have to be lattice-matched to the InP substrate, and in this embodiment, the compressive strain is 1.4%.

【００１２】以上の説明では、ＩｎＧａＡｓ（Ｐ）／Ｉ
ｎＧａＡｓＰ系量子井戸構造に対する実施例を述べた
が、本発明は、この構造に限定されるものではなく、他
のＭＱＷ構造、例えばＩｎＧａＡｓ／ＩｎＰ、ＩｎＧａ
Ａｓ／ＩｎＧａＡｓＰ、ＩｎＧａＡｓ／ＩｎＡｌＡｓ、
ＩｎＧａＡｌＡｓ／ＩｎＡｌＡｓ、ＧａＡｓ／ＡｌＧａ
Ａｓ、 ＩｎＧａＡｓ／ＧａＡｓ等のＭＱＷ構造にも適用
できることは言うまでもない。In the above description, InGaAs (P) / I
Although the embodiment for the nGaAsP-based quantum well structure has been described, the present invention is not limited to this structure, and other MQW structures such as InGaAs / InP and InGa are used.
As / InGaAsP, InGaAs / InAlAs,
InGaAlAs / InAlAs, GaAs / AlGa
It goes without saying that it can also be applied to MQW structures such as As and InGaAs / GaAs.

【００１３】[0013]

【発明の効果】本発明を適用すると、ノンドープ層の厚
さを５００ｎｍから１５００ｎｍ程度に設定できるの
で、量子井戸層にかかる電界の強さを適当にでき、か
つ、駆動電圧は最大数Ｖで動作する。このとき、素子容
量はノンドープ層の厚さで規定でき、高速応答が可能で
ある。また、量子井戸に隣接する障壁層のエネルギバン
ドギャップを傾斜させ、かつ、その分布を外部印加電界
で傾斜の角度が減少するように配置した構成とするとと
もに、クラッド層を傾斜構造としているため、電界が印
加されても障壁層を越えて電子が漏れることが少なく、
大きな吸収係数変化が得られる。また、量子井戸層の厚
さを素子容量に無関係にできるので、その層厚を５００
ｎｍから１５００ｎｍと薄くして光ファイバとの結合効
率をこれまでの素子に比べ数倍良好にできる。When the present invention is applied, the thickness of the non-doped layer can be set to about 500 nm to 1500 nm, so that the strength of the electric field applied to the quantum well layer can be made appropriate, and the driving voltage can operate at a maximum of several V. To do. At this time, the element capacitance can be defined by the thickness of the non-doped layer, and high-speed response is possible. In addition, since the energy band gap of the barrier layer adjacent to the quantum well is inclined, and the distribution is arranged so that the angle of inclination is reduced by an externally applied electric field, the cladding layer has an inclined structure, Even if an electric field is applied, electrons rarely leak beyond the barrier layer,
A large change in absorption coefficient is obtained. Moreover, since the thickness of the quantum well layer can be made independent of the device capacitance, the layer thickness is set to 500
The coupling efficiency with the optical fiber can be made several times better than the conventional devices by reducing the thickness from 1 nm to 1500 nm.

【００１４】以上の説明では、吸収係数変化を利用した
強度変調器を対象にしたが、吸収係数変化は屈折率変化
とクラマース・クレーニッヒの関係により結びつけられ
ており、屈折率変化を利用した位相変調器や、屈折率変
化に伴う干渉を利用した強度変調器にも適用できること
は言うまでもない。In the above description, the intensity modulator using the change of the absorption coefficient is targeted, but the change of the absorption coefficient is linked by the relationship between the change of the refractive index and the Kramers-Krenig, and the phase modulation using the change of the refractive index. It goes without saying that the present invention can also be applied to an intensity modulator that utilizes interference caused by a change in refractive index.

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

【図１】従来の多重量子井戸構造のエネルギバンド図で
あり、（ａ）はＩｎＧａＡｓ（Ｐ）／ＩｎＧａＡｓＰ多
重量子井戸構造、（ｂ）はＩｎＧａＡｓ／ＩｎＡｌＡｓ
多重量子井戸構造のエネルギバンド図である。FIG. 1 is an energy band diagram of a conventional multiple quantum well structure, (a) is an InGaAs (P) / InGaAsP multiple quantum well structure, and (b) is InGaAs / InAlAs.
It is an energy band figure of a multiple quantum well structure.

【図２】本発明の原理を示す図であって、単一量子井戸
構造に垂直な方向に電界が印加されると同時に障壁層に
も電界が印加された場合を説明するためのもので、
（ａ）は吸収係数の変化を示すグラフであり、（ｂ）は
エネルギバンド図である。FIG. 2 is a diagram showing the principle of the present invention, for explaining a case where an electric field is applied to a barrier layer at the same time as an electric field is applied in a direction perpendicular to a single quantum well structure,
(A) is a graph which shows change of an absorption coefficient, (b) is an energy band figure.

【図３】本発明の原理を示す図であって、単一量子井戸
構造のみに垂直な方向に電界が印加された場合を説明す
るためのもので、（ａ）は吸収係数の変化を示すグラフ
であり、（ｂ）はエネルギバンド図である。FIG. 3 is a diagram showing the principle of the present invention, which is for explaining a case where an electric field is applied in a direction perpendicular to only a single quantum well structure, and (a) shows a change in absorption coefficient. It is a graph and (b) is an energy band diagram.

【図４】障壁層にも電界の印加された場合の障壁層の形
状による電子の閉じ込めの相違を印加なしの場合と比較
して説明するためのもので、（ａ）は電界が印加されて
いないときのエネルギバンド図であり、（ｂ）は電界が
印加されたときのエネルギバンド図である。FIG. 4 is for explaining the difference in electron confinement due to the shape of the barrier layer when an electric field is applied also to the barrier layer, as compared with the case where no electric field is applied. (A) shows that an electric field is applied. It is an energy band diagram when there is no electric field, and (b) is an energy band diagram when an electric field is applied.

【図５】本発明を適用した実施例の導波形傾斜多重量子
井戸光制御素子の概略構成を示す斜視図である。FIG. 5 is a perspective view showing a schematic configuration of a waveguide-type tilted multiple quantum well light control device of an embodiment to which the present invention is applied.

【図６】図５のＡ部の詳細構成を示す組成図である。6 is a composition diagram showing a detailed configuration of a portion A in FIG.

【図７】本発明を適用した第２の実施例の導波形傾斜多
重量子井戸光制御素子の概略構成を示すエネルギバンド
図である。FIG. 7 is an energy band diagram showing a schematic configuration of a waveguide-type tilted multiple quantum well light control device of a second embodiment to which the present invention is applied.

【図８】障壁層にも電界が印加された場合の本発明に基
づいた多重量子井戸層の形状による電子の閉じ込めの相
違を印加なしの場合と比較して説明するためのものであ
り、（ａ）は電界が印加されていないときのエネルギバ
ンド図であり、（ｂ）は電界が印加されたときのエネル
ギバンド図である。FIG. 8 is for explaining the difference in electron confinement due to the shape of the multiple quantum well layer according to the present invention when an electric field is also applied to the barrier layer, as compared with the case where no electric field is applied. (a) is an energy band diagram when an electric field is not applied, and (b) is an energy band diagram when an electric field is applied.

【符号の説明】[Explanation of symbols]

１ ｎ−ＩｎＰ基板 ２ ＩｎＧａＡｓＰ第一クラッド層 ３ ＩｎＧａＡｓＰ第二クラッド層 ４ ＩｎＧａＡｓＰ第三クラッド層 ５ 単一量子井戸層 ６ ＩｎＧａＡｓＰ第一クラッド層 ７ ＩｎＧａＡｓＰ第二クラッド層 ８ ＩｎＧａＡｓＰ第三クラッド層 ９ ＩｎＧａＡｓキャップ層 １０ Ｐ電極 １１ Ｎ電極 １２ Ｐ形不純物領域 １３ Ｎ形不純物領域 １４ 領域型クラッド層 1 n-InP substrate 2 InGaAsP first clad layer 3 InGaAsP second clad layer 4 InGaAsP third clad layer 5 single quantum well layer 6 InGaAsP first clad layer 7 InGaAsP second clad layer 8 InGaAsP third clad layer 9 InGaAs cap Layer 10 P electrode 11 N electrode 12 P type impurity region 13 N type impurity region 14 Region type cladding layer

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 厚さが励起子のボーア半径より薄い第１
のバンドギャップエネルギを持つ第１の半導体層と、前
記第１の半導体層より大きなバンドギャップエネルギを
持つ第２の半導体層からなる多重量子井戸構造をコア層
とする導波構造を有し、 前記第２の半導体層はバンドギャップエネルギがその厚
さ方向に傾斜した組成からなることを特徴とする導波形
傾斜多重量子井戸光制御素子。1. A first device having a thickness smaller than a Bohr radius of an exciton.
A first semiconductor layer having a bandgap energy of 2 and a second semiconductor layer having a bandgap energy larger than that of the first semiconductor layer, the waveguide structure having a multiple quantum well structure as a core layer, The waveguide type multi-quantum well optical control device, wherein the second semiconductor layer has a composition in which the band gap energy is graded in the thickness direction. 【請求項２】 前記コア層の周りを、前記第２の半導体
層のうち最大のバンドギャップエネルギと等しいかこれ
より大きなバンドギャップエネルギを持ち、かつ前記中
心コアより離れるに従って順次バンドギャップエネルギ
の増加する層により挟んだ屈折率傾斜型分離光閉じ込め
多重量子井戸導波構造を有することを特徴とする請求項
１に記載の導波形傾斜多重量子井戸光制御素子。2. The core layer has a bandgap energy equal to or larger than the maximum bandgap energy of the second semiconductor layer, and the bandgap energy increases sequentially with increasing distance from the central core. 2. The waveguide type tilted multiple quantum well optical control device according to claim 1, having a graded refractive index separated optical confinement multiple quantum well waveguide structure sandwiched between layers. 【請求項３】 前記導波構造の両側が互いに導電形が異
なる半導体層で挟まれ、外部から該導波構造に垂直に電
界が印加されると、前記第２の半導体層の傾斜したバン
ドギャップエネルギ分布が外部印加電界で傾斜の角度が
減少する特性を有することを特徴とする請求項１または
２のいずれかに記載の導波形傾斜多重量子井戸光制御素
子。3. The inclined bandgap of the second semiconductor layer when both sides of the waveguide structure are sandwiched by semiconductor layers having different conductivity types and an external electric field is applied perpendicularly to the waveguide structure. 3. The waveguide type multi-quantum well optical control device according to claim 1, wherein the energy distribution has a characteristic that the angle of inclination decreases with an externally applied electric field.
JP5333259A 1993-12-27 1993-12-27 Waveguide type inclined multiple quantum well optical control element Pending JPH07191289A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5333259A JPH07191289A (en) 1993-12-27 1993-12-27 Waveguide type inclined multiple quantum well optical control element

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5333259A JPH07191289A (en) 1993-12-27 1993-12-27 Waveguide type inclined multiple quantum well optical control element

Publications (1)

Publication Number Publication Date
JPH07191289A true JPH07191289A (en) 1995-07-28

Family

ID=18264113

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5333259A Pending JPH07191289A (en) 1993-12-27 1993-12-27 Waveguide type inclined multiple quantum well optical control element

Country Status (1)

Country Link
JP (1) JPH07191289A (en)

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