JP4224981B2 - Surface emitting semiconductor laser device and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface emitting semiconductor laser device and a manufacturing method thereof, and more particularly to a vertical cavity surface emitting semiconductor laser device and a manufacturing method thereof.
[0002]
[Prior art]
In the semiconductor laser, a surface emitting semiconductor laser element as disclosed in JP-A-8-139412 and JP-A-2000-174340, or edge emission as disclosed in JP-A-11-54843 is disclosed. There is a semiconductor laser element.
[0003]
Among the surface emitting semiconductor laser elements, a vertical cavity surface emitting laser (VCSEL) element can not only obtain a light beam having a circular cross section but also two-dimensionally emit a plurality of light emitting portions. In other words, it can be integrated at a high density on a single substrate. The VCSEL operates with low power consumption and can be manufactured at low cost.
Due to these features, VCSELs have attracted attention as light sources for next-generation communication and optical information processing, and various studies have been conducted so far.
[0004]
The surface-emitting semiconductor laser device has an optical resonator in the vertical direction of the substrate, and a high-reflection multilayer film having a reflectivity close to 100% called a DBR (Distributed Bragg Reflector) mirror is used as a reflecting mirror. The laser light is amplified in the light emitting region.
[0005]
This DBR mirror has a refractive index (n) different from each other, and two thin layers each having a thickness of λ / 4 (λ: wavelength) are paired and stacked on 20 to 40 layers to achieve a reflectance of 100%. It is close.
[0006]
However, if the compositional difference is increased, the heterojunction barrier existing at the junction between the two layers constituting the DBR mirror becomes large, and the element resistance increases. Conversely, if the composition difference is reduced, it is necessary to increase the number of pairs of DBR mirrors in order to ensure a desired reflectivity, and the heterojunction barrier is reduced, but the mirror thickness is increased, so that the element resistance is increased. Will cause.
[0007]
The element resistance caused by the DBR mirror is very high, from 100Ω to 200Ω, which is disadvantageous for high-speed operation required for future optical communication and the like.
In order to improve the drawbacks of the DBR mirror described above, conventional surface emitting semiconductor laser elements have several structures, and typical examples will be described below.
[0008]
FIG. 12A is a cross-sectional view of a surface emitting semiconductor laser element according to a conventional example.
12A includes an n-type DBR mirror 102, an n-type cladding layer 103, an active layer 104, a p-type cladding layer 105, and a p-type DBR mirror 106 on an n-type GaAs substrate 101. The p-side electrode 109 is formed on the p-type DBR mirror 106 via the p-type cap layer 107, and the n-type GaAs substrate 101 is on the opposite side of the n-type DBR mirror 102 from the lamination side. An n-side electrode 111 is formed.
[0009]
The n-type DBR mirror 102 has, for example, a multilayer structure in which n-type AlAs layers and n-type GaAs layers are alternately stacked as two types of semiconductor materials having different refractive indexes.
[0010]
As shown in the enlarged cross-sectional view of FIG. 12B, the p-type DBR mirror 106 is made of Al with a small composition ratio of aluminum constituting the mirror and a thickness d1._x Ga_1-x As (x = 0 to 0.2) layer 106a and Al having a large composition ratio of aluminum and thickness d2_x Ga_1-x Between the As (x = 0.8 to 1.0) layer 106b, the composition ratio of aluminum is Al._x Ga_1-x Al with a thickness of d3 between the As layers 106a and 106b._x Ga_1-x An As (x = 0.4 to 0.6) layer 106c is inserted as an intermediate layer to form one set, and is formed by stacking dozens of the above sets.
[0011]
At this time, the doping concentration of the p-type impurity in the p-type DBR mirror 106 is 1 × 10 5 only for the intermediate layer portion of the p-type DBR mirror 106.¹⁸atoms / cm^Three It is preferable to perform high concentration doping as described above. This is because when the p-type impurity is uniformly doped into the p-type DBR mirror 106, non-radiative recombination centers are generated in the entire p-type DBR mirror 106, and the reactive current increases.
[0012]
In the surface emitting semiconductor laser elements shown in FIGS. 12A and 12B, the heterojunction barrier becomes steep by inserting an intermediate layer having an intermediate composition ratio between layers having a large composition ratio. Therefore, element resistance can be reduced.
[0013]
FIG. 13 is a cross-sectional view of a surface emitting semiconductor laser device according to another conventional example.
In the surface emitting semiconductor laser device shown in FIG. 13, an n-type DBR mirror 202, an n-type cladding layer 203, an active layer 204, a p-type cladding layer 205, and a p-type DBR mirror 206 are laminated on an n-type GaAs substrate 201. A p-side electrode 209 is formed on the p-type cladding layer 205 in a region avoiding the p-type DBR mirror 206 via a p-type cap layer 207, and the n-type DBR mirror 202 of the n-type GaAs substrate 201 is formed. An n-side electrode 211 is formed on the side opposite to the stacked side.
[0014]
The n-type DBR mirror 202 has, for example, a multilayer structure in which n-type AlAs layers and n-type GaAs layers are alternately stacked as two types of semiconductor materials having different refractive indexes, and a p-type DBR mirror 206. Similarly, for example, it has a multilayer structure in which p-type AlAs layers and p-type GaAs layers are alternately stacked.
[0015]
In the structure shown in FIG. 13, since the p-side electrode 209 is formed on the p-type cladding layer 205 in the region avoiding the p-type DBR mirror 206 via the p-type cap layer 207, the p-type DBR mirror 206 is formed. It is not necessary to consider this resistance, and since current can be injected into the active layer 204, the element resistance can be reduced.
[0016]
Due to the structure of the surface emitting semiconductor laser element shown in FIGS. 12 and 13, the element resistance of the surface emitting semiconductor laser element is 10 to 15Ω, and the resistance of the element has been dramatically reduced.
[0017]
[Problems to be solved by the invention]
However, each of the above conventional surface-emitting semiconductor laser devices has problems.
In the surface emitting semiconductor laser device shown in FIGS. 12A and 12B, in order to form the p-type DBR mirror 106, an AlGaAs layer 106b having a small aluminum composition ratio and an AlGaAs layer 106b having a large aluminum composition ratio are formed. The AlGaAs layer 106c having an intermediate aluminum composition ratio must be inserted, and the epitaxial profile becomes much more complicated than before, and the epitaxial layer composition, film thickness, impurity doping profile, etc. are precisely controlled. Must be done. As a result, it is an obstacle to manufacturing a surface emitting laser element having a stable structure at low cost.
[0018]
Further, in the surface emitting semiconductor laser element shown in FIG. 13, since the p-side electrode 209 is formed away from the p-type DBR mirror 206, the current injection region is separated from the light emitting region of the active layer 204 by more than a few tens μm. The current component flowing in the shortest path to the active layer 204 immediately below the p-side electrode 209 increases, and light emission concentrates in the peripheral portion rather than the central portion in the light emitting region of the active layer 204.
For this reason, the emitted light intensity observed from the outside has become non-uniform in that the central part is low and the peripheral part is strong. Furthermore, in the prior art, the p-type DBR mirror 206 has to be finely processed to a few tens of μm in order to reduce the threshold current and form the electrode on the p-type cladding layer 205. There was a problem that the physical strength of the mirror 206 would be very low.
[0019]
Further, as shown in Japanese Patent Laid-Open No. 2000-261088, etc., since the output characteristics generally fluctuate due to changes in temperature, the heat dissipation characteristics are improved in the edge emitting semiconductor laser element. The same applies to a semiconductor laser device, and it is desired to produce a surface emitting semiconductor laser device having excellent temperature characteristics by dissipating heat generated by light emission in the light emitting region of the active layer to the outside.
[0020]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surface emitting semiconductor laser element having a low element resistance, excellent temperature characteristics, and a stable structure, and a method for manufacturing the same.
[0021]
[Means for Solving the Problems]
  In order to achieve the above object, the surface emitting semiconductor laser device of the present invention isFirstA reflective multilayer film;A first reflection layer formed on the first reflective multilayer film;A cladding layer;Formed in the first cladding layer;An active layer having a light emitting region;A second clad layer formed in the light emitting region of the active layer and a second reflective multilayer film formed in the second clad layer are laminated, and the first reflective multilayer is formed in the laminating direction. A first layer formed in an outer peripheral region centering on the light emitting region in a direction perpendicular to the stacking direction through the film to the first cladding layer.Electrodes,In a position facing the first electrode across the active layer and the first cladding layer in the stacking direction, and in a direction orthogonal to the stacking direction, the outer periphery of the second reflective multilayer film has the first A second electrode having a plurality of electrodes formed concentrically or concentrically up to two cladding layers, the light emitting region, the first cladding layer, the second cladding layer, the second cladding layer, The reflective multilayer film 1 and the second reflective multilayer film constitute an optical resonator..
[0022]
  According to the surface-emitting semiconductor laser device of the present invention described above,First and secondSince a part of the electrode is embedded in the optical resonator so as to approach the active layer in the vicinity of the optical resonant area excluding the optical resonant area of the optical resonator, the light emitting region from the electrode to the active layer is formed. The path for injecting current into the is reduced. Further, when the electrode approaches the light emitting region of the active layer, heat generated by light emission in the light emitting region of the active layer is transmitted to the electrode and is dissipated out of the element through the electrode. Furthermore, when the electrode approaches the light emitting region of the active layer, when light deviated from the optical resonance area is reflected by the electrode, it is returned to the light emitting region of the active layer again.
[0023]
  Furthermore, in order to achieve the above object, a method for manufacturing a surface emitting semiconductor laser device of the present invention includes:FirstA reflective multilayer film;The first reflective multilayer film has a firstA cladding layer;In the first cladding layer,An active layer having a light emitting region;The second cladding layer and the second reflective multilayer film are sequentially formedLaminating steps;In the stacking direction, the second reflective multilayer film is disposed on the outer periphery of the second reflective multilayer film at a position facing the first electrode across the active layer and the first cladding layer and in a direction perpendicular to the stacking direction. For the second electrode having a plurality of electrodes formed concentrically or concentrically to the cladding layerForming a groove; andFor second electrodeEmbedded in the groove of theSecondOn reflective multilayerSecondForming an electrode;Grooves for the first electrode in the outer peripheral region centering on the light emitting region in the direction perpendicular to the stacking direction through the first reflective multilayer film in the stacking direction to the first cladding layer And forming a first electrode on the first reflective multilayer film by filling the groove for the first electrodeAnd have.
[0024]
  According to the manufacturing method of the surface emitting semiconductor laser device of the present invention,First and secondWhen forming the electrode, a groove is formed in the optical resonator layer in the vicinity of the optical resonance area excluding the optical resonance area of the optical resonator layer, and the electrode is formed on the reflective multilayer film by filling the groove. Thus, the surface emitting semiconductor laser element having the above-described action is manufactured. Since the path for injecting current from the electrode to the light emitting region of the active layer is shortened, the restriction due to the resistance value is eased in the production of the reflective multilayer film.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a surface emitting semiconductor laser device and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.
[0026]
First embodiment
FIG. 1 is a sectional view of a surface emitting semiconductor laser device according to this embodiment.
In the surface-emitting semiconductor laser device shown in FIG. 1, an n-type reflective multilayer film 2, an n-type cladding layer 3, an active layer 4, a p-type cladding layer 5, a p-type reflective multilayer film 6 and p are formed on an n-type GaAs substrate 1. An epitaxial growth layer composed of the mold cap layer 7 is formed.
[0027]
The epitaxial growth layer on the active layer 4 side of the n-type reflective multilayer film 2 is insulated by ion implantation of protons or oxygen ions except for the element formation region, thereby forming the element isolation insulating film 8. Has been.
[0028]
The n-type reflective multilayer film 2, the n-type clad layer 3, the active layer 4, the p-type clad layer 5, and the p-type reflective multilayer film 6 formed on the n-type GaAs substrate 1 constitute an optical resonator. The central portion of the epitaxial growth layer surrounded by the isolation insulating film 8 serves as an optical resonance area Ar, and the active layer 4 in the optical resonance area Ar serves as a light emitting region that substantially emits light. The diameter of the optical resonance area Ar is, for example, about 2 to 5 μm.
[0029]
A plurality of grooves are formed in the epitaxial growth layer from the p-type cap layer 7 to the n-type cladding layer 3 so as to avoid the optical resonance area Ar and from the vicinity of the optical resonance area Ar to the outside. A p-side electrode 9 which is embedded and has a comb-like cross section is formed. A diffusion region 10 into which zinc for achieving ohmic contact with the p-side electrode 9 is introduced is formed in a portion connected to the p-side electrode 9 in the epitaxial growth layer.
[0030]
The groove is formed concentrically from the optical resonance area Ar. As shown in the top view of FIG. 2, the embedded portion 91 of the p-side electrode 9 embedded in the epitaxial growth layer has a laser beam exit opening. It is formed concentrically around C.
[0031]
The p-type cap layer 7 and the p-side electrode 9 are removed at the laser beam exit C, and an n-side electrode 11 is provided on the side opposite to the laminated side of the n-type reflective multilayer film 2 of the n-type GaAs substrate 1. Is formed.
Below, an example of a structure of the said laminated structure is demonstrated in detail.
[0032]
The n-type reflective multilayer film 2 has a structure in which two types of semiconductor materials having different refractive indexes, for example, an n-type AlAs layer and an n-type GaAs layer are repeatedly stacked as a pair, and a distributed reflector (Distributed Bragg Reflector). : DBR). The DBR has a refractive index (n) different from each other, and two thin layers each having a thickness of λ / 4 (λ: wavelength) are paired, and the reflectance is obtained by stacking them in dozens of layers (20 to 40). The mirror is close to 100%. The n-type reflective multilayer film 2 is made of, for example, SiO.₂ And Ti₂ A dielectric mirror in which a plurality of dielectric layers are stacked with O as a pair may be used.
[0033]
The active layer 4 is made of, for example, In that functions as a well layer._0.2 Ga_0.8 It has a strained quantum well structure including As and GaAs functioning as a barrier layer, and an n-type cladding layer 3 and a p-type cladding layer 5 are formed with the active layer 4 interposed therebetween. n-type Al_0.5 Ga_0.5 It is made of As, and the p-type cladding layer 5 is made of p-type Al._0.5 Ga_0.5 It consists of As.
[0034]
The p-type reflective multilayer film 6 has, for example, a structure in which a p-type AlAs layer and a p-type GaAs layer are repeatedly laminated as a pair, and functions as an upper distributed reflector (DBR). Note that the p-type reflective multilayer film 6 may be constituted by the above-described dielectric mirror.
[0035]
The p-type cap layer 7 is provided to form an ohmic contact with the p-side electrode 9, and is made of, for example, p-type GaAs into which Zn, which is a p-type impurity, is introduced at a high concentration. An opening is formed at the emission port C.
[0036]
The p-side electrode 9 is formed, for example, by sequentially stacking, for example, a Ti layer / Pt layer / Au layer from the p-type cap layer 7 side, and the n-side electrode 11 is formed, for example, from the n-type GaAs substrate 1 side by AuGe. An alloy layer / Ni layer / Au layer is laminated in order.
[0037]
Next, a method for manufacturing the surface-emitting semiconductor laser device according to this embodiment having the above-described configuration will be described with reference to FIGS.
[0038]
First, as shown in FIG. 3A, on an n-type GaAs substrate 1, an n-type reflective multilayer film 2, an n-type cladding layer 3, an active layer 4, a p-type cladding layer 5, a p-type reflective multilayer film 6, A plurality of semiconductor layers constituting the p-type cap layer 7 are epitaxially grown by MBE (molecular beam epitaxy), MOCVD (organic metal vapor phase epitaxy), or the like.
[0039]
Next, as shown in FIG. 3B, a resist is applied on the p-type cap layer 7 to form a resist mask 20 that protects the element formation region by lithography, and the resist mask 20 is used as a mask. By ion-implanting oxygen ions, protons, etc., the epitaxial growth layer up to the n-type cladding layer 3 is insulated, and the element isolation insulating film 8 is formed. Thereafter, the resist mask 20 is removed.
[0040]
Next, as shown in FIG. 4C, a resist is applied again on the p-type cap layer 7, and the resist mask 21 is formed in a pattern that protects the optical resonance area Ar by lithography and has an opening in the groove formation region. Then, by performing anisotropic etching such as RIE (Reactive Ion Etching) using the resist mask 21 as an etching mask, a groove M penetrating the active layer 4 from the p-type cap layer 7 is formed. Thereafter, the resist mask 21 is removed.
[0041]
Next, as shown in FIG. 4D, a resist is applied again on the p-type cap layer 7, and a resist mask 22 having a pattern for protecting the optical resonance area Ar is formed by lithography, and the resist mask 22 is formed. As a mask, the diffusion region 10 is formed by diffusing zinc in the epitaxial growth layer.
[0042]
Next, as shown in FIG. 5E, after the electrode material to be the p-side electrode is completely buried in the groove M, the resist mask 22 is removed together with the metal material deposited on the resist mask 22 by a lift-off method. Then, the p-side electrode 9 embedded in the groove M and having an opening at the laser beam emission port C is formed.
[0043]
Finally, as shown in FIG. 5F, an n-side electrode 11 is formed by depositing an electrode material on the n-type GaAs substrate 1 to form a predetermined pattern, and using the p-side electrode 9 as a mask. By removing the p-type cap layer 7 exposed at the laser beam exit C by etching, the surface emitting semiconductor laser device according to the present embodiment is manufactured.
[0044]
In the surface emitting semiconductor laser device according to the present embodiment having the above-described configuration, the current injection is performed in the vicinity of the light emitting region of the active layer 4 by embedding a part of the p-side electrode 9 in the p-type reflective multilayer film 6 as described above. Directly on the p-type cladding layer 5 in FIG. This is because current does not pass through the p-type reflective multilayer film 6, so that it is not necessary to inject impurities into the p-type reflective multilayer film 6 to reduce the resistance. Generation of non-radiative recombination centers can be suppressed, and reactive current due to the non-radiative recombination centers can be reduced.
[0045]
At the same time, the fact that current does not pass through the p-type reflective multilayer film 6 makes it unnecessary to take measures against the heterojunction barrier of the DBR mirror, which has been indispensable for reducing the resistance, so that the composition ratio of the semiconductor material constituting the DBR mirror The degree of freedom for manufacturing the DBR mirror can be improved, for example, the reflectance can be secured with a smaller number of pairs, and a DBR mirror that is simple and easy to control can be manufactured. it can.
[0046]
Further, since the metal material such as the p-side electrode 9 generally has a smaller thermal resistance than the semiconductor material such as GaAs or AlGaAs constituting the surface emitting semiconductor laser element, the p-side electrode 9 having a small thermal resistance is By approaching the light emitting region of the active layer 4 in the resonance area Ar to about several μm, heat generated by light emission in the light emitting region is transferred to the p-side electrode 9 and dissipated out of the element. Can also efficiently dissipate heat and improve temperature characteristics.
[0047]
In addition, since a plurality of p-side electrodes 9 are embedded concentrically so as to surround the light emitting region of the active layer 4 in the optical resonance area Ar, a plurality of embedded portions 91 formed around the resonance area Ar are used. The light leaked from the optical resonance area Ar of the p-type reflective multilayer film 6 can be reflected and returned to the light emitting region of the active layer 4 again, and the current efficiency can be improved by reusing the leaked light. As a result, the threshold value and operating current can be reduced.
[0048]
In the present embodiment, since the optical resonance area Ar is formed by the embedded portion 91 of the p-side electrode 9 embedded in the p-type reflective multilayer film 6 of about several tens μm to several hundreds μm, the p-type reflective multilayer is formed. The physical strength of the film 6 can be improved, and the handling property and the yield in manufacturing can be improved.
[0049]
Second embodiment
FIG. 6 is a cross-sectional view of the surface emitting semiconductor laser device according to this embodiment. In addition, the same code | symbol is attached | subjected to the same component as the surface emitting semiconductor laser element which concerns on 1st Embodiment, The description is abbreviate | omitted here.
[0050]
In the surface emitting semiconductor laser device shown in FIG. 6, only one groove surrounding the vicinity of the optical resonance area Ar is formed in the epitaxial growth layer from the p-type cap layer 7 to the n-type cladding layer 3 in a region avoiding the optical resonance area Ar. The p-side electrode 9 is formed by being embedded in the groove. The p-side electrode 9 has such a shape that only the embedded portion 91 closest to the laser beam emission port C shown in FIG. 2 is formed.
[0051]
As a manufacturing method of the surface emitting semiconductor laser device having the above-described configuration, in the first embodiment, it is manufactured by changing the shape of the resist mask 21 in the groove forming step shown in FIG.
[0052]
According to the surface emitting semiconductor laser device having the above configuration, there is only one embedded portion 91 surrounding the periphery of the optical resonance area Ar, but compared with the first embodiment, the heat generated in the light emitting region of the active layer 4 is reduced. Although the effect of diffusion and reuse of leaked light is reduced, it is considered that the same effect can be obtained in terms of element resistance and physical strength.
[0053]
Third embodiment
FIG. 7 is a cross-sectional view of the surface emitting semiconductor laser device according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same component as the surface emitting semiconductor laser element which concerns on 1st Embodiment, The description is abbreviate | omitted here.
[0054]
In the surface-emitting semiconductor laser device shown in FIG. 7, as in the second embodiment, the epitaxial growth layer from the p-type cap layer 7 to the n-type cladding layer 3 has an optical resonance area Ar in a region avoiding the optical resonance area Ar. Only one groove surrounding the vicinity of the electrode is formed, and the p-side electrode 9 is formed in the groove. The p-side electrode 9 has such a shape that only the embedded portion 91 closest to the laser beam emission port C shown in FIG. 2 is formed.
[0055]
In this embodiment, a plurality of concentric grooves similar to those of the first embodiment, for example, are formed on the surface of the p-type cap layer 7 and embedded in the grooves formed in the p-type cap layer 7. By forming the p-side electrode 9, the buried portion 92 is also provided in the p-type cap layer 7.
[0056]
As a method of manufacturing the surface emitting semiconductor laser device having the above-described configuration, in the first embodiment, a resist mask is similarly formed before or after the formation step of the groove M by the resist mask 21 in the groove formation step shown in FIG. The p-type cap layer 7 is manufactured by patterning a groove for forming the buried portion 92 by etching.
[0057]
In the surface emitting semiconductor laser device having the above configuration, the same effect as that of the second embodiment can be obtained, and the cross-sectional area through which current flows can be increased in the p-type electrode formed on the p-type cap layer 7. The resistance can be reduced as compared with the second embodiment.
[0058]
Fourth embodiment
FIG. 8 is a cross-sectional view of the surface emitting semiconductor laser device according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same component as the surface emitting semiconductor laser element which concerns on 1st Embodiment, The description is abbreviate | omitted here.
[0059]
In the surface-emitting semiconductor laser device shown in FIG. 8, as in the second embodiment, only one groove surrounding the vicinity of the optical resonance area Ar is formed in the epitaxial growth layer in a region avoiding the optical resonance area Ar. The p-side electrode 9 is formed so as to be embedded in the groove.
[0060]
In the present embodiment, unlike the second embodiment, the embedded portion 91 a of the p-type electrode 9 embedded in the trench is formed so as to be embedded partway through the p-type cladding layer 5 without penetrating the active layer 4. .
[0061]
As a manufacturing method of the surface emitting semiconductor laser device having the above-described configuration, in the first embodiment, it is manufactured by changing the shape and etching depth of the resist mask 21 in the groove forming step shown in FIG.
[0062]
In the surface-emitting semiconductor laser device having the above configuration, the distance between the embedded portion 91a and the light emitting region of the active layer 4 is longer than that of the second embodiment, and the periphery of the light emitting region of the active layer 4 is embedded in the embedded portion 91a. Since the heat dissipation generated in the light emitting region of the active layer 4 and the reuse of leaked light are lower than those in the second embodiment, the element resistance and physical strength are the same. It is thought that the effect of can be acquired.
[0063]
Fifth embodiment
FIG. 9 is a cross-sectional view of the surface emitting semiconductor laser device according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same component as the surface emitting semiconductor laser element which concerns on 1st Embodiment, The description is abbreviate | omitted here.
[0064]
In the surface emitting semiconductor laser element shown in FIG. 9, a groove surrounding the vicinity of the optical resonance area Ar is formed in a region avoiding the optical resonance area Ar from the n-type GaAs substrate 1 to the n-type cladding layer 3. An n-side electrode 11 having a comb-like cross section is formed so as to be embedded in the groove, and an embedded portion 11a is also provided on the n-side electrode 11 side.
In the n-type cladding layer 3 from the n-type GaAs substrate 1, a diffusion region 12 into which an n-type impurity is introduced is formed in a portion connected to the n-side electrode 11 in order to achieve ohmic contact with the n-side electrode 11. Yes.
In the present embodiment, a plurality of embedded portions 91a having the same depth as in the fourth embodiment are formed, and the p-side electrode 9 having a comb-like cross section is formed.
[0065]
As a method of manufacturing the surface emitting semiconductor laser device having the above-described configuration, in the first embodiment, a groove reaching from the n-type GaAs substrate 1 to the middle of the n-type cladding layer 3 before the n-side electrode deposition step shown in FIG. After forming, the n-side electrode is deposited.
[0066]
In the surface emitting semiconductor laser device according to this embodiment having the above-described configuration, the current injection is performed in the light emitting region of the active layer 4 by embedding a part of the n-side electrode 11 in the n-type reflective multilayer film 2 as described above. Since it is directly performed on the n-type cladding layer 3 in the vicinity, the resistance can be further reduced as compared with the first embodiment.
Further, since the embedded portion 11a of the n-side electrode 11 is close to the light emitting region of the active layer 4, the n-side electrode 11 can also function to dissipate heat generated by light emission in the light emitting region to the outside of the element. Further, the heat dissipation characteristics can be improved.
Further, since the embedded portion 11a of the n-side electrode 11 surrounds part of the n-type reflective multilayer film 2 and the n-type cladding layer 3 in the optical resonance area Ar, the optical resonance area Ar of the n-type reflective multilayer film 2 Since the light leaked from the light can be reflected and returned to the light emitting region of the active layer 4 again, the current efficiency can be improved by reusing the leaked light as compared with the first embodiment. As a result, the threshold value and operating current can be reduced.
[0067]
The present invention is not limited to the description of the above embodiment.
For example, in the present embodiment, an example in which the p-side electrode 9 is concentrically embedded has been described. However, the present invention is not limited to this, and may be embedded in a square shape as shown in FIG. It may be embedded in a rectangular shape as shown in FIG. In this way, it is possible to control the polarization by making the electrodes rectangular instead of circular.
Further, the depth and number of the buried portions of the p-side electrode 9 and the n-side electrode 11 have various variations, and are not limited to those described in the above embodiment.
[0068]
In the present embodiment, an example in which the step of diffusing zinc before the deposition of the p-side electrode in order to achieve ohmic contact with the p-side electrode 9 has been described. However, the present invention is not limited to this example. When a laminated film of zinc and gold is used as the material, zinc is diffused by performing heat treatment after the deposition of the p-side electrode, and the same effect as the above treatment can be obtained.
In addition, various modifications can be made without departing from the scope of the present invention.
[0069]
【The invention's effect】
According to the present invention, it is possible to realize a surface-emitting semiconductor laser device having reduced element resistance, excellent temperature characteristics, and a stable structure.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a surface emitting semiconductor laser device according to a first embodiment.
FIG. 2 is a top view of the surface emitting semiconductor laser element according to the first embodiment.
FIG. 3 is a process sectional view in the manufacture of the surface emitting semiconductor laser element according to the first embodiment.
FIG. 4 is a process sectional view in the manufacture of the surface emitting semiconductor laser element according to the first embodiment.
FIG. 5 is a process sectional view in the manufacture of the surface emitting semiconductor laser element according to the first embodiment.
FIG. 6 is a cross-sectional view of a surface emitting semiconductor laser device according to a second embodiment.
FIG. 7 is a cross-sectional view of a surface emitting semiconductor laser device according to a third embodiment.
FIG. 8 is a cross-sectional view of a surface emitting semiconductor laser device according to a fourth embodiment.
FIG. 9 is a cross-sectional view of a surface emitting semiconductor laser device according to a fifth embodiment.
FIG. 10 is a top view showing another example of the electrode shape of the surface emitting semiconductor laser device according to the embodiment.
FIG. 11 is a top view showing another example of the electrode shape of the surface emitting semiconductor laser device according to the embodiment.
12A is a cross-sectional view of a surface emitting semiconductor laser device according to a conventional example, and FIG. 12B is an enlarged cross-sectional view of a p-type DBR mirror shown in FIG. 12A.
FIG. 13 is a cross-sectional view of a surface emitting semiconductor laser device according to another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... n-type GaAs substrate, 2 ... n-type reflective multilayer film, 3 ... n-type clad layer, 4 ... Active layer, 5 ... p-type clad layer, 6 ... p-type reflective multilayer film, 7 ... p-type cap layer, 8 ... element isolation insulating film, 9 ... p-side electrode, 91, 91a, 92 ... buried portion, 10 ... diffusion region, 11 ... n-side electrode, 11a ... buried portion, 12 ... diffusion region, 20, 21, 22 ... resist mask , 101 ... n-type GaAs substrate, 102 ... n-type DBR mirror, 103 ... n-type cladding layer, 104 ... active layer, 105 ... p-type cladding layer, 106 ... p-type DBR mirror, 107 ... p-type cap layer, 109 ... p-side electrode, 111 ... n-side electrode, 201 ... n-type GaAs substrate, 202 ... n-type DBR mirror, 203 ... n-type cladding layer, 204 ... active layer, 205 ... p-type cladding layer, 206 ... p-type DBR mirror, 207 ... p-type cap , 209 ... p-side electrode, 211 ... n-side electrode, C ... laser emitting port, Ar ... optical resonator area.

Claims (6)

A first reflective multilayer film;
A first cladding layer formed on the first reflective multilayer film ;
An active layer formed in the first cladding layer and having a light emitting region;
A second cladding layer formed in the light emitting region of the active layer;
A second reflective multilayer film formed on the second cladding layer;
Is composed of stacked layers,
A first electrode formed in an outer peripheral region centering on the light emitting region in a direction perpendicular to the stacking direction through the first reflective multilayer film in the stacking direction to the first cladding layer; ,
In a position facing the first electrode across the active layer and the first cladding layer in the stacking direction, and in a direction orthogonal to the stacking direction, the outer periphery of the second reflective multilayer film has the first A second electrode having a plurality of electrodes formed concentrically or concentrically up to two cladding layers;
Formed,
A surface emitting semiconductor laser device in which the light emitting region, the first cladding layer, the second cladding layer, the first reflective multilayer film, and the second reflective multilayer film constitute an optical resonator . Wherein the contact portion between the contact portion and the second electrode of the first electrode, the surface emitting semiconductor laser device according to claim 1 wherein the conductive impurity is introduced in the optical resonator. It said first and second reflection multilayer films, multilayer surface-emitting semiconductor laser element according to claim 2, wherein is formed by the Bragg reflector or by a semiconductor, according to the dielectric. A first reflective multilayer film; a first clad layer on the first reflective multilayer film; an active layer having a light emitting region on the first clad layer; a second clad layer; and a second reflective multilayer film. And sequentially laminating
In the stacking direction, the second reflective multilayer film is disposed on the outer periphery of the second reflective multilayer film at a position facing the first electrode across the active layer and the first cladding layer and in a direction perpendicular to the stacking direction. Forming a groove for a second electrode having a plurality of electrodes formed concentrically or concentrically up to the cladding layer ,
Forming a second electrode on the second of said embedded in the trench of the electrode second reflection multilayer film,
Grooves for the first electrode in the outer peripheral region centering on the light emitting region in the direction perpendicular to the stacking direction through the first reflective multilayer film in the stacking direction to the first cladding layer Forming a step;
And a step of forming a first electrode on the first reflective multilayer film by filling the groove for the first electrode . After the step of forming the groove for the first electrode, before the step of forming the first electrode, the first electrode in the optical resonator layer including the inside of the groove for the first electrode Diffusing conductive impurities in contact parts with
After the step of forming the groove for the second electrode and before the step of forming the second electrode, the second electrode in the optical resonator layer including the inside of the groove for the second electrode The method of manufacturing a surface-emitting semiconductor laser device according to claim 4, further comprising a step of diffusing conductive impurities in a contact portion with the substrate. 6. The method of manufacturing a surface emitting semiconductor laser device according to claim 5, wherein the first and second reflective multilayer films are formed of a dielectric multilayer film or a semiconductor Bragg reflector.

Images