JP2007087994A - Surface-emitting semiconductor laser element - Google Patents

Surface-emitting semiconductor laser element Download PDF

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JP2007087994A
JP2007087994A JP2005271410A JP2005271410A JP2007087994A JP 2007087994 A JP2007087994 A JP 2007087994A JP 2005271410 A JP2005271410 A JP 2005271410A JP 2005271410 A JP2005271410 A JP 2005271410A JP 2007087994 A JP2007087994 A JP 2007087994A
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layer
resonator
semiconductor laser
emitting semiconductor
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Seteiagun Kashimirusu
セティアグン カシミルス
Tatsuo Kageyama
健生 影山
Hideaki Nagoshi
秀昭 名越
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Furukawa Electric Co Ltd
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<P>PROBLEM TO BE SOLVED: To provide a surface-emitting semiconductor laser element which can improve optical output while keeping high-speed operational characteristic in high-temperature environment. <P>SOLUTION: A plurality of active layers 42 having a multiple quantum well structure comprised of a Ga<SB>1-x</SB>In<SB>x</SB>N<SB>y1</SB>As<SB>1-y1-y2</SB>Sb<SB>y2</SB>(0.1<x, 0<y1<0.03, 0≤y2≤0.06) well layer 43 and a GaN<SB>z1</SB>As<SB>1-z1-z2-z3</SB>Sb<SB>z2</SB>P<SB>z3</SB>barrier layer 44 (0<z1≤0.05, 0≤z2≤0.06, 0≤z3≤0.2) are provided in a resonator 41, in a manner that an approx center of the respective active layers 42 may be located in the antinode of a standing wave pattern in the resonator 41. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、面発光半導体レーザ素子に関し、特に発振波長が１．０〜１．６μｍ帯で高光出力でかつ高温環境において高速動作特性を有する面発光半導体レーザ素子に関するものである。   The present invention relates to a surface-emitting semiconductor laser device, and more particularly to a surface-emitting semiconductor laser device having an oscillation wavelength of 1.0 to 1.6 μm, high optical output, and high-speed operation characteristics in a high temperature environment.

面発光半導体レーザ素子は同一基板上に２次元的に多数のレーザ素子を集積配置できる特長を備えており、光インターコネクションや光コンピューティングなどの光の並列性を生かした並列光情報処理、或いは大容量並列光伝送などへの応用に適している。   A surface emitting semiconductor laser element has a feature that a large number of laser elements can be integrated and arranged two-dimensionally on the same substrate, and parallel optical information processing that utilizes parallelism of light such as optical interconnection or optical computing, or Suitable for applications such as large-capacity parallel optical transmission.

近年、ＧａＡｓ基板上に、相互にＡｌ組成の異なるＡｌＧａＡｓ／ＡｌＧａＡｓ等のペアが複数積層された半導体多層膜反射鏡が対をなすように形成され、前記一対の半導体多層膜反射鏡の間にＧａx Ｉｎ1-x Ｎy Ａｓ1-y 系活性層が形成された、発振波長が１．０〜１．６μｍ帯の面発光半導体レーザ素子が高温環境において高速動作特性を有し、光通信装置の光源として注目されている。 In recent years, semiconductor multilayer reflectors in which a plurality of pairs of AlGaAs / AlGaAs having different Al compositions are laminated on a GaAs substrate are formed to form a pair, and Ga between the pair of semiconductor multilayer reflectors. A surface emitting semiconductor laser element having an oscillation wavelength of 1.0 to 1.6 μm formed with an x In 1-x N y As 1-y active layer has high-speed operation characteristics in a high temperature environment, and an optical communication device Has attracted attention as a light source.

従来の１．０〜１．６μｍ帯のＧａx Ｉｎ1-x Ｎy Ａｓ1-y 系活性層を有する面発光半導体レーザ素子の一例について、図５を用いて説明する。
図５に示すように、面発光半導体レーザ素子１０は、ｎ−ＧａＡｓ基板１２上に、ｎ−ＧａＡｓ／Ａｌ0.9 Ｇａ0.1 Ａｓのペアを積層してなる下部ＤＢＲ半導体多層膜反射鏡１４と、ｎ−ＧａＡｓクラッド層１８と、発振波長が１．３μｍのＧａxＩｎ1-xＮyＡｓ1-y井戸層を有する多重量子井戸構造の活性層２０と、ｐ−ＧａＡｓクラッド層２２と、ｐ−ＧａＡｓ／Ａｌ0.9 Ｇａ0.1 Ａｓのペアを積層してなる上部ＤＢＲ半導体多層膜反射鏡２４と、ｐ−ＧａＡｓコンタクト層２６とを順次積層した積層構造を備えている。
注入電流を効率良く閉じ込めるために、活性層２０と上部ＤＢＲ反射鏡２４の間には、電流注入領域として設けられたｐ−ＡｌＡｓ層１７と、電流注入領域の外側の電流狭窄層として設けられたＡｌ酸化層１６が形成されている。Ａｌ酸化層１６は、ＡｌＡｓ層のＡｌを選択的に酸化して形成されている。
また、積層構造上には、保護膜としてＳｉＮ膜３２が成膜されている。メサ上にはｐ−ＧａＡｓコンタクト層２６に接続するリング状のｐ側電極３４、およびｐ側電極３４の引出し用電極３６が設けられている。また、ｎ−ＧａＡｓ基板１２の裏面にはｎ側電極３８が設けてある。
上記構成により、面発光半導体レーザ素子１０は、ｎ−ＧａＡｓ基板１２に直交し、かつ積層構造側の方向にレーザ光を出射する。
特開２００３−１７９３０８号公報 An example of a conventional surface-emitting semiconductor laser element having a Ga x In 1-x N y As 1-y active layer in the 1.0 to 1.6 μm band will be described with reference to FIG.
As shown in FIG. 5, the surface emitting semiconductor laser device 10 includes a lower DBR semiconductor multilayer reflector 14 in which an n-GaAs / Al 0.9 Ga 0.1 As pair is stacked on an n-GaAs substrate 12, A GaAs cladding layer 18, an active layer 20 having a multiple quantum well structure having a Ga x In 1-x N y As 1-y well layer with an oscillation wavelength of 1.3 μm, a p-GaAs cladding layer 22, and a p- It has a laminated structure in which an upper DBR semiconductor multilayer film reflecting mirror 24 formed by laminating a pair of GaAs / Al 0.9 Ga 0.1 As and a p-GaAs contact layer 26 are sequentially laminated.
In order to efficiently confine the injection current, a p-AlAs layer 17 provided as a current injection region and a current confinement layer outside the current injection region are provided between the active layer 20 and the upper DBR reflector 24. An Al oxide layer 16 is formed. The Al oxide layer 16 is formed by selectively oxidizing Al of the AlAs layer.
In addition, a SiN film 32 is formed as a protective film on the laminated structure. On the mesa, a ring-shaped p-side electrode 34 connected to the p-GaAs contact layer 26 and an extraction electrode 36 for the p-side electrode 34 are provided. An n-side electrode 38 is provided on the back surface of the n-GaAs substrate 12.
With the above configuration, the surface emitting semiconductor laser element 10 emits laser light in a direction perpendicular to the n-GaAs substrate 12 and on the side of the laminated structure.
JP 2003-179308 A

本発明者は鋭意実験した結果、図５に示した面発光半導体レーザ素子１０において、Ｇａx Ｉｎ1-x Ｎy Ａｓ1-y 系井戸層を有する多重量子井戸構造の活性層２０を構成する障壁層をＧａＮz Ａｓ1-zで構成することにより、比較的低い閾値電流密 度で１．３μｍ帯のレーザ発振が実現することを見出した。この際、１．３μｍ帯の発振波長を得るために、井戸層を構成するＧａx Ｉｎ1-x Ｎy Ａｓ1-y のＩｎ組成を３０％以上（ｘ≦０．７）、Ｎ組成を３％以下（ｙ≦０．０３）に設定した。 As a result of diligent experiments, the inventor forms an active layer 20 having a multiple quantum well structure having a Ga x In 1 -x N y As 1 -y well layer in the surface emitting semiconductor laser device 10 shown in FIG. It has been found that by forming the barrier layer with GaN z As 1-z , laser oscillation in the 1.3 μm band can be realized with a relatively low threshold current density. At this time, in order to obtain an oscillation wavelength in the 1.3 μm band, the In composition of Ga x In 1-x N y As 1-y constituting the well layer is 30% or more (x ≦ 0.7), and the N composition is It was set to 3% or less (y ≦ 0.03).

ところで、上記多重量子井戸構造では、ｎ−ＧａＡｓ基板１２上に積層されたＧａx Ｉｎ1-x Ｎy Ａｓ1-y 井戸層は高圧縮歪み（歪量εw ＞２％）を受け、一方、ＧａＮz Ａｓ1-z 障壁層は引っ張り歪み（歪量εb ＜−０．５％）を受ける。多重量子井戸構造の結晶性を保つためには、多重量子井戸構造のネット歪みεnet を零 に近く設定する必要がある。そのためには、上記井戸層の臨界膜厚は約７ｎｍであるので、障壁層は比較的に厚く、１５ｎｍ以上に設定する必要がある。
なお、ネット歪みεnet は、
εnet ＝（Ｎw εw Ｌw ＋Ｎb εb Ｌb ）／（Ｎw Ｌw ＋Ｎb Ｌb）
で与えられるものである。ここで、Ｎw は井戸層数、εw は井戸層における歪み、Ｌwは井戸層厚、Ｎb は障壁層数、εb は障壁層における歪み、Ｌb は障壁層厚である。
しかしながら、上述のように障壁層を厚くすると、面発光半導体レーザ素子の光出力が低下するという問題が生じた。また、多重量子井戸構造の結晶性を悪化させないようにするためには、井戸層数を少なく設定する必要があり、その結果十分な光出力が得られないという問題が生じた。 By the way, in the multiple quantum well structure, the Ga x In 1-x N y As 1-y well layer stacked on the n-GaAs substrate 12 is subjected to high compressive strain (strain amount ε w > 2%). The GaN z As 1-z barrier layer is subjected to tensile strain (strain amount ε b <−0.5%). In order to maintain the crystallinity of the multiple quantum well structure, it is necessary to set the net strain ε net of the multiple quantum well structure close to zero. For that purpose, since the critical thickness of the well layer is about 7 nm, the barrier layer is relatively thick and needs to be set to 15 nm or more.
The net distortion ε net is
ε net = (N w ε w L w + N b ε b L b) / (N w L w + N b L b)
Is given by Here, N w is the number of well layers, ε w is the strain in the well layers, L w is the thickness of the well layers, N b is the number of barrier layers, ε b is the strain in the barrier layers, and L b is the thickness of the barrier layers.
However, when the barrier layer is made thick as described above, there arises a problem that the light output of the surface emitting semiconductor laser element is lowered. Further, in order not to deteriorate the crystallinity of the multiple quantum well structure, it is necessary to set the number of well layers to be small, and as a result, there is a problem that a sufficient light output cannot be obtained.

本発明は、上述した問題に鑑み、光出力を向上させた、特に高温環境において高速動作特性を維持しながら光出力を向上させた面発光半導体レーザ素子を提供することを目的とする。   In view of the above-described problems, an object of the present invention is to provide a surface-emitting semiconductor laser device that has improved light output, particularly while maintaining high-speed operation characteristics in a high temperature environment.

本発明の第１発明は、請求項１に記載のように、ＧａＩｎＮＡｓ（Ｓｂ）井戸層とＧａＮＡｓ（Ｓｂ）（Ｐ）障壁層とからなる多重量子井戸の活性層が共振器内に設けられた面発光半導体レーザ素子において、前記活性層は複数個が前記共振器内に設けられ、各活性層はそれぞれの略中心が前記共振器中の定在波パターンの腹の部分に位置するように前記共振器内に設けられていることを特徴とする面発光半導体レーザ素子である。ここで、活性層の中心とは、活性層の厚さ方向の中心を意味する。また、井戸層はＳｂを含んでも含まなくてもよく、障壁層はＳｂ、Ｐを含んでも含まなくてもよい。
上述のように、ＧａＩｎＮＡｓ系の多重量子井戸からなる複数の活性層の略中心を、共振器に伝搬する定在波の腹（強度の極大箇所）に位置させることにより、光出力を向上させることができる。
第１発明は、面発光半導体レーザ素子の光出力は多重量子井戸の中を伝搬する定在波の電界の強さの２乗に比例することに注目したものである。即ち、多重量子井戸構造の活性層の結晶性の悪化を防ぐために、活性層を構成する多重量子井戸の井戸層数を少なくしても、複数の活性層をそれぞれの略中心が共振器を伝搬する定在波の腹に位置するように配置することにより、多重量子井戸の中を伝搬する定在波の電界を強め、各量子井戸からの光出力を強め、その総和である全体としての光出力を向上させることができる。
レーザ波長を１３００ｎｍとし、ＧａＡｓの屈折率を３．４５とすれば、１／２λ共振器長は約１９０ｎｍになる。従って、光出力は理想的な特性に対して９５％以上を維持するための、共振器を伝搬する定在波の腹に対する複数の活性層の各略中心の好ましい位置は、次式でより導くことができる。
１９０−［ａｒｃｓｅｃ（（０．９５）1/2）×（２／π）×１９０］＝約３０ｎｍ
以上のように、共振器を伝搬する定在波の腹の両側３０ｎｍ以内に、活性層の略中心を配置することが好ましい。 According to a first aspect of the present invention, an active layer of a multi-quantum well comprising a GaInNAs (Sb) well layer and a GaNAs (Sb) (P) barrier layer is provided in the resonator as described in claim 1. In the surface-emitting semiconductor laser device, a plurality of the active layers are provided in the resonator, and each active layer is positioned so that a substantially center of each of the active layers is located at an antinode of the standing wave pattern in the resonator. The surface-emitting semiconductor laser device is provided in a resonator. Here, the center of the active layer means the center of the active layer in the thickness direction. The well layer may or may not contain Sb, and the barrier layer may or may not contain Sb and P.
As described above, the optical output is improved by positioning the approximate center of a plurality of active layers composed of GaInNAs-based multiple quantum wells at the antinode (maximum intensity point) of the standing wave propagating to the resonator. Can do.
The first invention pays attention to the fact that the optical output of the surface emitting semiconductor laser element is proportional to the square of the strength of the electric field of the standing wave propagating in the multiple quantum well. That is, in order to prevent deterioration of the crystallinity of the active layer of the multi-quantum well structure, even if the number of well layers of the multi-quantum well constituting the active layer is reduced, a plurality of active layers propagate through the resonator at their respective centers. By placing them so that they are located at the antinodes of standing waves, the electric field of the standing waves propagating in the multiple quantum wells is strengthened, the light output from each quantum well is strengthened, and the total light that is the sum of them The output can be improved.
If the laser wavelength is 1300 nm and the refractive index of GaAs is 3.45, the 1 / 2λ resonator length is about 190 nm. Therefore, in order to maintain the optical output at 95% or more with respect to the ideal characteristic, a preferable position of each approximate center of the plurality of active layers with respect to the antinodes of the standing wave propagating through the resonator is derived from the following equation. be able to.
190− [arcsec ((0.95) 1/2 ) × (2 / π) × 190] = about 30 nm
As described above, it is preferable to arrange the approximate center of the active layer within 30 nm on both sides of the antinode of the standing wave propagating through the resonator.

上記について、共振器内における電界強度の２乗を算出した結果により、説明する。計算に用いたパラメーターは、発振波長λが１３００ｎｍ、井戸層厚Ｌw が７．３ｎｍ、障壁層厚Ｌb が１６ｎｍ、また共振器の実効屈折率ｎeff が３．４５、共振器長が２λ／ｎeff である。
図１（ａ）は、共振器内における電界強度の２乗の変化を示す図である。
図１（ａ）において、曲線Ａは、図１（ｂ）に示すように、３重量子井戸構造でネット歪みεnet が０．３３％である１個の活性層を、３個の井戸層の中心の井戸層 が共振器中の定在波パターンの腹の部分に位置するように、共振器中に設けた場合を示す。また、曲線Ｂは、図１（ｃ）に示すように、前記活性層を２個、それぞれの中心の井戸層が共振器中の定在波パターンの腹の部分に位置するように、共振器中に設けた場合を示す。さらに、曲線Ｃは、図１（ｄ）に示すように、前記活性層を３個、それぞれの中心の井戸層が共振器中の定在波パターンの腹の部分に位置するように、周期的に設けた場合を示す。
図１（ａ）からわかるように、光出力に相当する電界強度の２乗は、活性層が１個である曲線Ａに対して、活性層が２個である曲線Ｂは２倍、活性層が３個である曲線Ｃは３倍になる。 The above will be described based on the result of calculating the square of the electric field strength in the resonator. The parameters used for the calculation were as follows: the oscillation wavelength λ was 1300 nm, the well layer thickness L w was 7.3 nm, the barrier layer thickness L b was 16 nm, the effective refractive index n eff of the resonator was 3.45, and the resonator length was 2λ. / N eff .
FIG. 1A is a diagram showing a change in the square of the electric field strength in the resonator.
In FIG. 1 (a), a curve A indicates that one active layer having a triple quantum well structure and a net strain ε net of 0.33% is represented by three well layers as shown in FIG. 1 (b). This shows a case where the center well layer is provided in the resonator so that the well layer is located at the antinode of the standing wave pattern in the resonator. Further, as shown in FIG. 1 (c), the curve B indicates that the two active layers and the center well layer of each of the active layers are located at the antinodes of the standing wave pattern in the resonator. The case where it is provided is shown. Furthermore, as shown in FIG. 1 (d), the curve C shows that the three active layers are arranged periodically such that the central well layer is located at the antinode of the standing wave pattern in the resonator. The case where it is provided is shown.
As can be seen from FIG. 1A, the square of the electric field intensity corresponding to the light output is twice that of the curve B having two active layers compared to the curve A having one active layer. Curve C with three is tripled.

また、第２発明は、請求項２に記載のように、請求項１において、前記各活性層の略中心は、前記共振器中の定在波パターンの腹の両側略３０ｎｍ以内に位置するように前記共振器内に設けられていることを特徴とする面発光半導体レーザ素子である。
前記多重量子井戸の井戸層と障壁層の伝導帯バンドオフセットエネルギーは４００ｍｅＶ以下であり、価電子帯バンドオフセットエネルギーは２００ｍｅＶ以下であることを特徴とする面発光半導体レーザ素子である。
レーザ波長を１３００ｎｍとし、ＧａＡｓの屈折率を３．４５とすれば、１／２λ共振器長は約１９０ｎｍになる。従って、光出力は理想的な特性に対して９５％以上を維持するための、共振器を伝搬する定在波の腹に対する複数の活性層の各略中心の好ましい位置は、次式でより導くことができる。
１９０−［ａｒｃｓｅｃ（（０．９５）1/2）×（２／π）×１９０］＝約３０ｎｍ
以上のように、共振器を伝搬する定在波の腹の両側３０ｎｍ以内に、活性層の略中心を配置することが好ましい。 According to a second aspect of the present invention, as recited in the second aspect, in the first aspect, the approximate center of each active layer is located within approximately 30 nm on both sides of the antinode of the standing wave pattern in the resonator. The surface-emitting semiconductor laser device is provided in the resonator.
The surface emitting semiconductor laser device is characterized in that the conduction band offset energy of the well layer and the barrier layer of the multiple quantum well is 400 meV or less and the valence band offset energy is 200 meV or less.
If the laser wavelength is 1300 nm and the refractive index of GaAs is 3.45, the 1 / 2λ resonator length is about 190 nm. Therefore, in order to maintain the optical output at 95% or more with respect to the ideal characteristic, a preferable position of each approximate center of the plurality of active layers with respect to the antinodes of the standing wave propagating through the resonator is derived from the following equation. be able to.
190− [arcsec ((0.95) 1/2 ) × (2 / π) × 190] = about 30 nm
As described above, it is preferable to arrange the approximate center of the active layer within 30 nm on both sides of the antinode of the standing wave propagating through the resonator.

また、第３発明は、請求項３に記載のように、請求項１ないし２において、前記多重量子井戸の井戸層と障壁層の伝導帯バンドオフセットエネルギーは４００ｍｅＶ以下であり、価電子帯バンドオフセットエネルギーは２００ｍｅＶ以下であることを特徴とする面発光半導体レーザ素子である。   According to a third aspect of the present invention, in the first or second aspect, the conduction band offset energy of the well layer and the barrier layer of the multiple quantum well is 400 meV or less, and the valence band offset The surface emitting semiconductor laser device is characterized in that the energy is 200 meV or less.

本発明は、鋭意実験した結果に基づくものである。
光出力を向上させるためには、活性層を構成する多重量子井戸の各井戸層へのキャリア注入効率が重要なパラメーターとなる。そこで、本発明者は量子井戸構造とキャリア注入効率との関係を調べた。図２は、レーザ発振の閾値電流密度と井戸層と障壁層間の伝導帯バンドオフセットエネルギーとの関係を示す一例である。図２に示すように、井戸層と障壁層間の伝導帯バンドオフセットエネルギーが４００ｍｅＶを超えると、閾値電流密度が著しく増加する。これは、伝導帯バンドオフセットエネルギーが４００ｍｅＶを超えると、井戸層へのキャリア注入効率が低下することに起因する。従って、光出力を向上させるためには井戸層と障壁層間の伝導帯バンドオフセットエネルギーを４００ｍｅＶ以下に設定することが好ましい。
同様に、井戸層と障壁層間の価電子帯バンドオフセットエネルギーは、２００ｍｅＶ以下に設定することが好ましい。 The present invention is based on the results of earnest experiments.
In order to improve the optical output, the carrier injection efficiency into each well layer of the multiple quantum wells constituting the active layer is an important parameter. Therefore, the present inventor investigated the relationship between the quantum well structure and the carrier injection efficiency. FIG. 2 is an example showing the relationship between the threshold current density of laser oscillation and the conduction band offset energy between the well layer and the barrier layer. As shown in FIG. 2, when the conduction band offset energy between the well layer and the barrier layer exceeds 400 meV, the threshold current density significantly increases. This is because when the conduction band offset energy exceeds 400 meV, the carrier injection efficiency into the well layer decreases. Therefore, in order to improve the light output, it is preferable to set the conduction band offset energy between the well layer and the barrier layer to 400 meV or less.
Similarly, the valence band offset energy between the well layer and the barrier layer is preferably set to 200 meV or less.

また、第４発明は、請求項４に記載のように、請求項１ないし３において、前記多重量子井戸構造の障壁層にはｐ型変調ドープが施されることを特徴とする面発光半導体レーザ素子である。電子に比べて正孔の拡散長が短いため、多重量子井戸構造の障壁層にｐ型変調ドープを施すことによって井戸層への正孔注入効率が向上できる。   A fourth aspect of the present invention is the surface emitting semiconductor laser according to the fourth aspect, wherein the barrier layer of the multiple quantum well structure is subjected to p-type modulation doping in the first to third aspects. It is an element. Since the diffusion length of holes is shorter than that of electrons, the efficiency of hole injection into the well layer can be improved by applying p-type modulation doping to the barrier layer of the multiple quantum well structure.

また、第５発明は、請求項５に記載のように、請求項１ないし４において、前記多重量子井戸のネット歪εnet は、−０．５％≦εnet ≦０．５％であることを特徴とする面発光半導体レーザ素子である。
上述のように、ネット歪εnet を−０．５％≦εnet ≦０．５％に設定すると、多重量子井戸の結晶性を良好に保つことができる。 According to a fifth aspect of the present invention, as described in the fifth aspect, in the first to fourth aspects, the net strain ε net of the multiple quantum well is −0.5% ≦ ε net ≦ 0.5%. A surface emitting semiconductor laser device characterized by the following.
As described above, when the net strain ε net is set to −0.5% ≦ ε net ≦ 0.5%, the crystallinity of the multiple quantum well can be kept good.

また、第６発明は、請求項６に記載のように、請求項１ないし５において、前記多重量子井戸の井戸層数Ｎw は、３≦Ｎw ≦１２であることを特徴とする面発光半導体レーザ素子である。
上述のように、井戸層数Ｎw を３≦Ｎw ≦１２に設定すると、多重量子井戸の結晶性を良好に保つことができる。 According to a sixth aspect of the present invention, as in the sixth aspect of the present invention, in the first to fifth aspects, the number of well layers N w of the multiple quantum well is 3 ≦ N w ≦ 12. It is a semiconductor laser element.
As described above, when the number of well layers N w is set to 3 ≦ N w ≦ 12, the crystallinity of the multiple quantum well can be kept good.

また、第７発明は、請求項７に記載のように、請求項１ないし６において、前記共振器を構成する二つの反射鏡は半導体多層膜反射鏡からなり、前記二つの半導体多層膜反射鏡中に、注入電流を狭窄する電流狭窄層を設けたことを特徴とする面発光半導体レーザ素子である。
多重量子井戸構造からなる複数の活性層を共振器中に定在波パターンの腹の部分に位置するように設けて光出力を向上させるためには、共振器長を長くする必要がある。そうすると、注入電流を狭窄する電流狭窄層を共振器の注入する側にのみ設けただけでは、注入電流が共振器中で広がり、その結果、レーザ光のスペクトル幅が増加し、又は単一モードが得られにくくなる。そこで、第６発明のように、共振器両側の二つの半導体多層膜反射鏡中に、注入電流を狭窄する電流狭窄層を設けると、レーザ光のスペクトル幅を狭く、又は単一モードを維持しながら光出力を向上させることができる。 According to a seventh aspect of the present invention, according to the seventh aspect of the present invention, in the first to sixth aspects, the two reflecting mirrors constituting the resonator are semiconductor multilayer reflecting mirrors, and the two semiconductor multilayer reflecting mirrors. In the surface emitting semiconductor laser device, a current confinement layer for confining an injection current is provided therein.
In order to improve the light output by providing a plurality of active layers having a multiple quantum well structure so as to be located in the antinodes of the standing wave pattern in the resonator, it is necessary to increase the resonator length. Then, if a current confinement layer for confining the injection current is provided only on the side where the resonator is injected, the injection current spreads in the resonator, resulting in an increase in the spectral width of the laser beam or a single mode. It becomes difficult to obtain. Therefore, if a current confinement layer for constricting the injection current is provided in the two semiconductor multilayer reflectors on both sides of the resonator as in the sixth aspect of the invention, the spectrum width of the laser beam is narrowed or the single mode is maintained. The light output can be improved.

本発明によれば、ＧａＩｎＮＡｓ系の１．３μｍ帯面発光半導体レーザ素子において、高温環境において高速の動作特性を維持しながら高い光出力を得ることができるという優れた効果を有する。   According to the present invention, a GaInNAs 1.3 μm band surface emitting semiconductor laser device has an excellent effect that a high light output can be obtained while maintaining high-speed operation characteristics in a high temperature environment.

以下、図面に基づいて本発明の実施の形態を詳細に説明する。
図３は、本発明にかかる面発光半導体レーザ素子の一実施形態の発振部分を示す要部断面図である。図３において、従来の面発光半導体レーザ素子の説明に用いた図５に関して説明した部分と同部分は同符号で指示し、詳細な説明は省略する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 3 is a cross-sectional view of an essential part showing an oscillation part of one embodiment of the surface emitting semiconductor laser device according to the present invention. In FIG. 3, the same parts as those described with reference to FIG. 5 used for the description of the conventional surface emitting semiconductor laser element are designated by the same reference numerals, and detailed description thereof is omitted.

図３に示すように、本実施形態の面発光半導体レーザ素子４０は、ｎ−ＧａＡｓ基板１２上に、ｎ−ＧａＡｓ／Ａｌ0.9 Ｇａ0.1 Ａｓのペアを積層してなる下部ＤＢＲ半導体多層膜反射鏡１４と、共振器４１と、ｐ−ＧａＡｓ／Ａｌ0.9 Ｇａ0.1 Ａｓのペアを積層してなる上部ＤＢＲ半導体多層膜反射鏡２４と、ｐ−ＧａＡｓコンタクト層２６とを順次積層したものである。
図４は、上記実施形態の共振器４１部分を示す要部断面図である。共振器４１は、共振器長が１．５λ／ｎeff であり、その中に２個の活性層４２が設けられている 。また、４５はＧａＡｓクラッド層である。
前記活性層４２は、３重量子井戸からなり、前記３重量子井戸を構成する井戸層４３はＧａ0.61Ｉｎ0.39Ａｓ0.982 Ｎ0.018からなり、障壁層４４はＧａＮ0.019 Ａｓ0.981 からなり、その発振波長は１．２９５μｍ、ネット歪みεnet は０ ．３３％である。前記２個の活性層４２は、各々の３重量子井戸の中心の井戸層４３ａが共振器４１の定在波の腹に一致するよう設けられている。また、井戸層４３と障壁層４４の伝導帯バンドオフセットエネルギーは３５０ｍｅＶに、価電子帯バンドオフセットエネルギーは１００ｍｅＶになっている。
また、下部ＤＢＲ半導体多層膜反射鏡１４には、炭素イオン注入によりｎ型から高抵抗化した、注入電流を狭窄する電流狭窄層４６が形成されている。また、上部ＤＢＲ半導体多層膜反射鏡２４には、電流注入領域として設けられたｐ−ＡｌＡｓ層１７と、電流注入領域の外側の電流狭窄層として設けられたＡｌ酸化層１６が形成されている。
なお、共振器４１およびその周辺以外は、図５に示した従来の面発光半導体レーザ素子と同様の構造である。 As shown in FIG. 3, the surface emitting semiconductor laser device 40 according to the present embodiment includes a lower DBR semiconductor multilayer film reflecting mirror in which an n-GaAs / Al 0.9 Ga 0.1 As pair is stacked on an n-GaAs substrate 12. 14, a resonator 41, an upper DBR semiconductor multilayer mirror 24 formed by stacking a pair of p-GaAs / Al 0.9 Ga 0.1 As, and a p-GaAs contact layer 26 are sequentially stacked.
FIG. 4 is a cross-sectional view of the main part showing the resonator 41 portion of the above embodiment. The resonator 41 has a resonator length of 1.5λ / n eff , and two active layers 42 are provided therein. Reference numeral 45 denotes a GaAs cladding layer.
The active layer 42 is composed of a triple quantum well, the well layer 43 constituting the triple quantum well is composed of Ga 0.61 In 0.39 As 0.982 N 0.018 , the barrier layer 44 is composed of GaN 0.019 As 0.981 , and its oscillation wavelength Is 1.295 μm, the net distortion ε net is 0. 33%. The two active layers 42 are provided such that the center well layer 43a of each triplet well coincides with the antinode of the standing wave of the resonator 41. The conduction band offset energy of the well layer 43 and the barrier layer 44 is 350 meV, and the valence band offset energy is 100 meV.
The lower DBR semiconductor multilayer mirror 14 is provided with a current confinement layer 46 that constricts the injection current, which is increased in resistance from n-type by carbon ion implantation. In the upper DBR semiconductor multilayer mirror 24, a p-AlAs layer 17 provided as a current injection region and an Al oxide layer 16 provided as a current confinement layer outside the current injection region are formed.
Except for the resonator 41 and its periphery, the structure is the same as that of the conventional surface emitting semiconductor laser element shown in FIG.

本実施形態の面発光半導体レーザ素子４０は、有機金属気相成長法およびガスソース分子線エピタキシー法を組み合わせたハイブリッド法により、ｎ−ＧａＡｓ基板１２上に化合物半導体層からなる積層構造を形成し、次いで積層構造をメサエッチングし、次いで、蒸着により金属のｐ側電極３４、およびｐ側電極３４の引出し用電極３６を形成し、さらに、ｎ−ＧａＡｓ基板１２の裏面にｎ側電極３８を形成して製作した。   The surface-emitting semiconductor laser device 40 of the present embodiment forms a stacked structure composed of compound semiconductor layers on the n-GaAs substrate 12 by a hybrid method combining a metal organic vapor phase epitaxy method and a gas source molecular beam epitaxy method, Next, the laminated structure is mesa-etched, and then a metal p-side electrode 34 and an extraction electrode 36 for the p-side electrode 34 are formed by vapor deposition, and an n-side electrode 38 is formed on the back surface of the n-GaAs substrate 12. Made.

本実施形態が従来例と異なる特徴的なことは、以下の通りである。即ち、
１）共振器長が１．５λ／ｎeff であり、３重量子井戸からなる２個の活性層４２が、３重量子井戸の中心井戸層４３ａが共振器４１の定在波の腹の位置に一致するように周期的に形成されており、また、活性層４２の井戸層４３と障壁層４４の伝導帯バンドオフセットエネルギーが３５０ｍｅＶに、価電子帯バンドオフセットエネルギーが１００ｍｅＶになっていることである。
２）また、下部ＤＢＲ半導体多層膜反射鏡１４に電流狭窄層４６を設け、上部ＤＢＲ半導体多層膜反射鏡２４に電流狭窄層としてＡｌ酸化層１６を設け、共振器４１の両側で注入電流の電流狭窄が行われていることである。 What is different from the conventional example in this embodiment is as follows. That is,
1) The resonator length is 1.5λ / n eff , the two active layers 42 made of triplet wells, the center well layer 43a of the triplet well is located at the antinode of the standing wave of the resonator 41 In addition, the conduction band offset energy of the well layer 43 and the barrier layer 44 of the active layer 42 is 350 meV, and the valence band offset energy is 100 meV. is there.
2) Further, a current confinement layer 46 is provided in the lower DBR semiconductor multilayer reflector 14, an Al oxide layer 16 is provided as a current confinement layer in the upper DBR semiconductor multilayer reflector 24, and the current of the injected current is provided on both sides of the resonator 41. It is that stenosis is performed.

本実施形態の面発光半導体レーザ素子４０は、上記のような共振器４１の構造により、また、共振器４１の上下、即ち、下部ＤＢＲ半導体多層膜反射鏡１４と上部ＤＢＲ半導体多層膜反射鏡２４に注入電流の狭窄構造を設けることにより、８５℃の高温環境において（従来に比して約２倍の）２ｍＷの光出力を得ることができ、かつ、１０Ｇｂｐｓの高速の動作特性が実現できた。
なお、上部ＤＢＲ半導体多層膜反射鏡２４に電流狭窄層としてＡｌ酸化層１６を設け、下部ＤＢＲ半導体多層膜反射鏡１４には電流狭窄構造を設けない場合には、２ｍＷの光出力を得ることができたが、動作速度は２．５Ｇｂｐｓであった。 The surface-emitting semiconductor laser device 40 of the present embodiment has the above-described structure of the resonator 41, and the upper and lower sides of the resonator 41, that is, the lower DBR semiconductor multilayer reflector 14 and the upper DBR semiconductor multilayer reflector 24. By providing a constriction structure for the injection current, an optical output of 2 mW can be obtained in a high-temperature environment of 85 ° C. (about twice as much as before), and high-speed operating characteristics of 10 Gbps can be realized. .
If the upper DBR semiconductor multilayer reflector 24 is provided with an Al oxide layer 16 as a current confinement layer and the lower DBR semiconductor multilayer reflector 14 is not provided with a current confinement structure, a light output of 2 mW can be obtained. Although it was possible, the operation speed was 2.5 Gbps.

なお、上記実施形態は、本発明を具体化した一例であって、本願発明の技術的範囲を限定するものではない。例えば、ｎ型の下部ＤＢＲ半導体多層膜反射鏡１４に設ける電流狭窄構造は、下部ＤＢＲ半導体多層膜反射鏡１４に高抵抗のｉ型層を設け、前記ｉ型層をＳｉイオン注入により部分的にｎ型化して電流注入領域としてもよい。あるいは、多重量子井戸の障壁層にｐ型変調ドープを施してもよい。   In addition, the said embodiment is an example which actualized this invention, Comprising: The technical scope of this invention is not limited. For example, in the current confinement structure provided in the n-type lower DBR semiconductor multilayer reflector 14, a high resistance i-type layer is provided in the lower DBR semiconductor multilayer reflector 14 and the i-type layer is partially formed by Si ion implantation. An n-type may be used as a current injection region. Alternatively, p-type modulation doping may be applied to the barrier layer of the multiple quantum well.

（ａ）は、本発明において、共振器内における電界強度の２乗が活性層の数により変化する計算結果を示す図であり、（ｂ）〜（ｄ）はそれぞれ、（ａ）における曲線Ａ、ＢおよびＣの活性層の共振器内における配置を示す図である。(A) is a figure which shows the calculation result from which the square of the electric field strength in a resonator changes with the number of active layers in this invention, (b)-(d) is the curve A in (a), respectively. FIG. 3 is a diagram showing an arrangement of active layers of B, C and C in a resonator. 面発光半導体レーザ素子の活性層の井戸層と障壁層間の伝導帯バンドオフセットエネルギーと閾値電流密度との関係を示す図である。It is a figure which shows the relationship between the conduction band offset energy between the well layer of an active layer of a surface emitting semiconductor laser element, and a barrier layer, and a threshold current density. 本発明にかかる面発光半導体レーザ素子の一実施形態の要部断面である。It is a principal part cross section of one Embodiment of the surface emitting semiconductor laser element concerning this invention. 上記実施形態の共振器部の断面図である。It is sectional drawing of the resonator part of the said embodiment. 従来の面発光半導体レーザ素子の断面図である。It is sectional drawing of the conventional surface emitting semiconductor laser element.

符号の説明Explanation of symbols

１０、４０ 面発光半導体レーザ素子
１２ ｎ−ＧａＡｓ基板
１４ 下部ＤＢＲ半導体多層膜反射鏡
１６ Ａｌ酸化層
１７ ｐ−ＡｌＡｓ層
１８ ｎ−ＧａＡｓクラッド層
２０、４２ 活性層
２２ ｐ−ＧａＡｓクラッド層
２４ 上部ＤＢＲ半導体多層膜反射鏡
２６ ｐ−ＧａＡｓコンタクト層
３２ ＳｉＮ膜
３４ ｐ側電極
３６ 引出し用電極
３８ ｎ側電極
４１ 共振器
４３、４３ａ 井戸層
４４ 障壁層
４５ ＧａＡｓクラッド層
４６ 電流狭窄層 10, 40 Surface emitting semiconductor laser element 12 n-GaAs substrate 14 Lower DBR semiconductor multilayer mirror 16 Al oxide layer 17 p-AlAs layer 18 n-GaAs clad layer 20, 42 active layer 22 p-GaAs clad layer 24 upper DBR Semiconductor multilayer mirror 26 p-GaAs contact layer 32 SiN film 34 p-side electrode 36 extraction electrode 38 n-side electrode 41 resonator 43, 43a well layer 44 barrier layer 45 GaAs cladding layer 46 current confinement layer

Claims (7)

Ｇａ1-xＩｎxＮy1Ａｓ1-y1-y2Ｓｂy2（但し、０．１＜ｘ、０＜ｙ１＜０．０３、０≦ｙ２≦０．０６）井戸層とＧａＮz1Ａｓ1-z1-z2-z3Ｓｂz2Ｐz3障壁層（但し、０＜ｚ１≦０．０５、０≦ｚ２≦０．０６、０≦ｚ３≦０．２）とからなる多重量子井戸の活性層が共振器内に設けられた面発光半導体レーザ素子において、前記活性層は複数個が前記共振器内に設けられ、各活性層はそれぞれの略中心が前記共振器中の定在波パターンの腹の部分に位置するように前記共振器内に設けられていることを特徴とする面発光半導体レーザ素子。 Ga 1-x In x N y1 As 1-y1-y2 Sb y2 (where 0.1 <x, 0 <y1 <0.03, 0 ≦ y2 ≦ 0.06) well layer and GaN z1 As 1-z1 -Z2-z3 Sb z2 P z3 barrier layer (where 0 <z1 ≦ 0.05, 0 ≦ z2 ≦ 0.06, 0 ≦ z3 ≦ 0.2), the active layer of the multiple quantum well is in the resonator In the surface-emitting semiconductor laser device provided in the present invention, a plurality of the active layers are provided in the resonator, and each active layer is positioned at the center of the antinode of the standing wave pattern in the resonator. Thus, a surface emitting semiconductor laser device is provided in the resonator. 前記各活性層の略中心は、前記共振器中の定在波パターンの腹の両側略３０ｎｍ以内に位置するように前記共振器内に設けられていることを特徴とする請求項１に記載の面発光半導体レーザ素子。   The substantially center of each said active layer is provided in the said resonator so that it may be located within about 30 nm of both sides of the antinode of the standing wave pattern in the said resonator. Surface emitting semiconductor laser element. 前記多重量子井戸の井戸層と障壁層の伝導帯バンドオフセットエネルギーは４００ｍｅＶ以下であり、価電子帯バンドオフセットエネルギーは２００ｍｅＶ以下であることを特徴とする１ないし２のいずれか１項に記載の面発光半導体レーザ素子。   3. The surface according to claim 1, wherein the conduction band offset energy of the well layer and the barrier layer of the multiple quantum well is 400 meV or less, and the valence band offset energy is 200 meV or less. Light emitting semiconductor laser element. 前記多重量子井戸構造の障壁層にはｐ型変調ドープが施されることを特徴とする請求項１ないし３のいずれか１項に記載の面発光半導体レーザ素子。   4. The surface emitting semiconductor laser device according to claim 1, wherein the barrier layer of the multiple quantum well structure is subjected to p-type modulation doping. 前記多重量子井戸のネット歪εnet は、−０．５％≦εnet ≦０．５％であることを特徴とする請求項１ないし４のいずれか１項に記載の面発光半導体レーザ素子。 5. The surface emitting semiconductor laser device according to claim 1, wherein a net strain ε net of the multiple quantum well is −0.5% ≦ ε net ≦ 0.5%. 前記多重量子井戸の井戸層数Ｎw は、３≦Ｎw ≦１２であることを特徴とする請求項１ないし５のいずれか１項に記載の面発光半導体レーザ素子。 6. The surface emitting semiconductor laser device according to claim 1, wherein the number of well layers N w of the multiple quantum wells is 3 ≦ N w ≦ 12. 前記共振器を構成する二つの反射鏡は半導体多層膜反射鏡からなり、前記二つの半導体多層膜反射鏡中に、注入電流を狭窄する電流狭窄層を設けたことを特徴とする請求項１ないし６のいずれか１項に記載の面発光半導体レーザ素子。   The two reflecting mirrors constituting the resonator are semiconductor multilayer film reflecting mirrors, and a current confinement layer for constricting an injection current is provided in the two semiconductor multilayer film reflecting mirrors. 7. The surface emitting semiconductor laser device according to any one of 6 above.
JP2005271410A 2005-09-20 2005-09-20 Surface-emitting semiconductor laser element Pending JP2007087994A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009239176A (en) * 2008-03-28 2009-10-15 Dowa Electronics Materials Co Ltd Light emitting element
JP2012038882A (en) * 2010-08-06 2012-02-23 Canon Inc Surface emitting laser, surface emitting laser array, display device using surface emitting laser array as light source, printer head, and printer
JP2014112654A (en) * 2012-11-02 2014-06-19 Canon Inc Nitride semiconductor surface emitting laser and manufacturing method of the same
WO2019220795A1 (en) * 2018-05-18 2019-11-21 株式会社Ｑｄレーザ Surface emitting laser and inspection device
JP2022540011A (en) * 2019-06-27 2022-09-14 ルミレッズ リミテッド ライアビリティ カンパニー DBR structure of LED with reduced photodegradation

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009239176A (en) * 2008-03-28 2009-10-15 Dowa Electronics Materials Co Ltd Light emitting element
JP2012038882A (en) * 2010-08-06 2012-02-23 Canon Inc Surface emitting laser, surface emitting laser array, display device using surface emitting laser array as light source, printer head, and printer
JP2014112654A (en) * 2012-11-02 2014-06-19 Canon Inc Nitride semiconductor surface emitting laser and manufacturing method of the same
WO2019220795A1 (en) * 2018-05-18 2019-11-21 株式会社Ｑｄレーザ Surface emitting laser and inspection device
JP2022540011A (en) * 2019-06-27 2022-09-14 ルミレッズ リミテッド ライアビリティ カンパニー DBR structure of LED with reduced photodegradation
JP7164737B2 (en) 2019-06-27 2022-11-01 ルミレッズ リミテッド ライアビリティ カンパニー DBR structure of LED with reduced photodegradation
US11901702B2 (en) 2019-06-27 2024-02-13 Lumileds Llc LED DBR structure with reduced photodegradation

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