JP2005123416A - Surface emitting laser element and manufacturing method thereof, and surface emitting laser array and optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a surface emitting laser element capable of manufacturing with an enhanced yield the surface emitting laser elements having stable performance, and to provide the surface emitting laser element, a surface emitting laser array, and an optical transmission system. <P>SOLUTION: In the manufacturing method of a surface emitting laser element, a lower mirror, a resonator layer comprising a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on a semiconductor substrate; an upper electrode is connected to the uppermost face of the upper mirror or an upper contact layer comprising any semiconductor layer from the uppermost face of the upper mirror up to the active layer; and a lower electrode is connected to a rear side of the semiconductor substrate or a lower contact layer comprising any semiconductor layer from the rear side of the semiconductor substrate up to the active layer. After at least the upper or lower electrode is formed on a corresponding contact layer, a part of the electrode is removed by the wet etching method to form an opening for optical output. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface emitting laser element, a manufacturing method thereof, a surface emitting laser array, and an optical transmission system.

  A surface emitting laser has a structure in which a laser resonator is formed in a direction perpendicular to a semiconductor substrate and light is emitted in a direction perpendicular to the substrate. A high-reflectance semiconductor multilayer mirror (semiconductor DBR), a dielectric multilayer mirror (dielectric DBR), and a metal reflector are provided on each of the substrate and the surface, and an active layer is provided between these mirrors. Is provided. Two upper and lower spacer layers are provided between the active layer and the two reflecting mirrors. Furthermore, since current and light must be confined in the vicinity of the active layer and parasitic capacitance must be reduced in high-speed modulation, the laser structure has a semiconductor pillar structure and current confinement in the vicinity of the active layer Is generally provided.

  Thus, the surface emitting laser element can be driven with a low threshold current and low power consumption since the volume of the active layer can be reduced. Further, since the mode volume of the resonator is small, modulation of several tens of GHz is possible, which is suitable for high-speed transmission. In addition, the spread angle of the emitted light is small and coupling to the optical fiber is easy. Further, the surface emitting laser does not require cleavage for production and has a small element area, and thus can be parallelized and formed into a two-dimensional high-density array.

  Since surface emitting lasers have these advantages, in recent years, more and more information is being transmitted at high speed and large capacity in optical communication systems, and optical interfaces capable of high-speed data transmission between computers, between chips, and within chips. It is considered to be a key device in the connection field.

  Surface emitting lasers are also expected to be applied in the fields of optical memory and laser printers where a light source capable of writing with low power consumption with a simple optical system is desired.

  A typical conventional configuration of a surface emitting laser element will be described.

(Conventional configuration example A)
FIG. 1 is a view showing a surface emitting laser element of a conventional configuration example A. In FIG. In order to fabricate the surface emitting laser element of this conventional configuration example A, a lower semiconductor multilayer mirror (semiconductor) having the same conductivity as the substrate is formed on a p-type or n-type conductive semiconductor substrate by MOCVD or MBE. DBR), a lower semiconductor spacer layer, a semiconductor active layer, an upper semiconductor spacer layer, and an upper semiconductor DBR having conductivity opposite to that of the lower semiconductor DBR are sequentially grown to form a stacked film. Here, the uppermost layer of the upper semiconductor DBR is doped with impurities at a high concentration, and also serves as the upper contact layer.

  Further, this laminated film is processed into a semiconductor pillar structure by dry etching or wet etching. Also, a current confinement portion is formed. As the formation method, an Al (Ga) As layer is inserted into the laminated film and this layer is oxidized to remove an electric current path to form an insulating region, or protons and oxygen ions are activated from the laminated film surface. There are cases where an insulating region is formed by implantation in the vicinity of a layer, or an insulating region is formed by embedding the periphery of a semiconductor pillar with a material having a large band gap.

  Next, an upper electrode having an opening in the light output portion is formed on the upper contact layer. This opening is often made by a lift-off method. Further, a lower electrode is formed on the back surface of the substrate. The light output is extracted above the element.

  A conventional example aiming at further improvement based on this configuration is disclosed in Patent Document 1 and the like.

(Conventional configuration example B)
FIG. 2 is a view showing a surface emitting laser element of a conventional configuration example B. In FIG. In order to fabricate the surface emitting laser element of this conventional configuration example B, a lower semiconductor multilayer mirror (semiconductor) having the same conductivity as the substrate is formed on a p-type or n-type conductive semiconductor substrate by MOCVD or MBE. DBR), a lower semiconductor spacer layer, a semiconductor active layer, an upper semiconductor spacer layer, and an upper contact layer having a conductivity and a high impurity concentration opposite to those of the lower semiconductor DBR are sequentially grown to form a stacked film. Further, like the conventional configuration example A, this laminated film is processed into a semiconductor pillar structure, and a current confinement portion is formed. Next, an upper electrode having an opening in the light output portion is formed on the upper contact layer. This opening is often produced by a lift-off method. Subsequently, a dielectric DBR is provided on the contact layer in the opening by sputtering, EB vapor deposition or CVD. A lower electrode is provided on the back surface of the substrate. The light output is extracted above the element. A conventional example aiming at further improvement based on this configuration is shown in Patent Document 2 and the like.

  In both cases of the conventional configuration examples A and B described above, the step with many problems is a step of forming the opening of the upper electrode by the lift-off method. In this process, problems such as no opening, burrs occur in the opening, and problems such as the pattern dimension deviating from an appropriate value often occur, resulting in a decrease in yield and a large variation in laser characteristics.

In Patent Document 2, in order to solve these problems, a mask having a T-shaped cross section is formed using two types of mask materials having different solubility in a predetermined solvent, and the upper electrode film is formed by a lift-off method. A method of forming the opening is shown. However, this method complicates the process and increases the manufacturing cost.
Japanese Patent Laid-Open No. 11-340565 JP-A-6-291413

It is an object of the present invention to provide a surface emitting laser element manufacturing method, a surface emitting laser element, a surface emitting laser array, and an optical transmission system capable of manufacturing a surface emitting laser element with high yield and stable performance. Yes.

  In order to achieve the above object, according to a first aspect of the present invention, a lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on a semiconductor substrate, and the uppermost surface of the upper mirror is formed. Alternatively, the upper electrode is connected to the upper contact layer made of any semiconductor layer between the uppermost surface of the upper mirror and the active layer, and the lower contact made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. In a method of manufacturing a surface emitting laser device in which a lower electrode is connected to a layer, after forming at least one of the upper electrode and the lower electrode on the corresponding contact layer, a part of the electrode is removed by wet etching Thus, an opening for light output is formed.

  According to a second aspect of the present invention, in the method for manufacturing a surface emitting laser device according to the first aspect, after forming at least one of the upper electrode and the lower electrode on the corresponding contact layer, the electrode is A light output opening is formed by removing a part of the electrode by a wet etching method using an etchant that is easy to etch and difficult to etch the contact layer.

  According to a third aspect of the present invention, a lower mirror, a resonator layer including a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on a semiconductor substrate, and the upper mirror uppermost surface or the upper mirror uppermost surface is The upper electrode is connected to the upper contact layer made of any semiconductor layer between the active layers, and the lower electrode is connected to the lower contact layer made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. In the surface emitting laser device to be manufactured, an opening for light output is formed in at least one of the upper electrode and the lower electrode, and the electrode further includes Al, Ti, Cr, Si, Cu, Ta, Zr, Zn Bi, Sb, Sn, Hg, Fe, Co, Mg, Be, or an alloy containing them as a main component, and that the contact layer to which the electrodes are connected is GaAs It is a symptom.

  According to a fourth aspect of the present invention, a lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially laminated on a semiconductor substrate, and the upper mirror uppermost surface or the upper mirror uppermost surface is The upper electrode is connected to the upper contact layer made of any semiconductor layer between the active layers, and the lower electrode is connected to the lower contact layer made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. In the surface emitting laser element to be manufactured, an opening for light output is provided in either the upper electrode or the lower electrode, and a non-alloy ohmic contact is formed between the electrode and a contact layer to which the electrode is connected. It is characterized by having.

The invention according to claim 5 is the surface emitting laser element according to claim 4, wherein the electrode on which the non-alloy ohmic contact is formed is Al, Ti, Cr, Si, Cu, Ta, Zr, Zn, Bi, Sb, Sn, Hg, Fe, Co, Mg, Be, or an alloy containing them as a main component, the contact layer to which the electrode is connected is GaAs, and the impurity concentration of the contact layer is 1. It is characterized by being 0 × 10 ²⁰ cm ⁻³ or more.

  According to a sixth aspect of the present invention, in the surface-emitting laser element according to any one of the third to fifth aspects, the active layer includes a layer made of a GaInNAs-based material.

  According to a seventh aspect of the present invention, there is provided a surface emitting laser comprising a plurality of the surface emitting laser elements according to any one of the third to sixth aspects arranged in an array on a semiconductor substrate. It is an array.

  The invention according to claim 8 is characterized in that the surface emitting laser element according to any one of claims 3 to 6 or the surface emitting laser array according to claim 7 is used. This is an optical transmission system.

  According to the first and second aspects of the present invention, the lower mirror, the resonator layer composed of a plurality of semiconductor layers including the semiconductor active layer, and the upper mirror are sequentially laminated on the semiconductor substrate, and the upper mirror uppermost surface or upper portion is laminated. The upper electrode is connected to the upper contact layer made of any semiconductor layer between the mirror top surface and the active layer, and the lower contact layer made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface to the active layer In the method of manufacturing the surface emitting laser element to which the lower electrode is connected, after forming at least one of the upper electrode and the lower electrode on the corresponding contact layer, a part of the electrode is removed by wet etching. A light output opening is formed, and the light output opening is formed in the electrode by a simple lithography process with good controllability. Well, it is possible to manufacture the surface-emitting laser element of the stable performance.

  In particular, in the invention according to claim 2, in the method for manufacturing the surface emitting laser element according to claim 1, after forming at least one of the upper electrode and the lower electrode on the corresponding contact layer, the electrode is formed. Since the light output opening is formed by removing a part of the electrode by a wet etching method using an etching solution that is easy to etch and difficult to etch the contact layer, the function of the contact layer is not deteriorated. Therefore, it is possible to manufacture a surface emitting laser element with a good yield and stable performance without deteriorating the laser characteristics.

  According to the third aspect of the present invention, the lower mirror, the resonator layer composed of a plurality of semiconductor layers including the semiconductor active layer, and the upper mirror are sequentially stacked on the semiconductor substrate, and the upper mirror uppermost surface or the upper mirror uppermost layer is laminated. The upper electrode is connected to the upper contact layer made of any semiconductor layer between the upper surface and the active layer, and the lower electrode is connected to the lower contact layer made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer In the surface emitting laser element to which is connected, an optical output opening is formed in at least one of the upper electrode and the lower electrode, and the electrode further includes Al, Ti, Cr, Si, Cu, Ta, Zr. Zn, Bi, Sb, Sn, Hg, Fe, Co, Mg, Be, or an alloy containing them as a main component, and the contact layer to which the electrodes are connected is GaAs. The electrode material of the surface-emitting laser element, since the material that the etching hardly electrode contact layer can be selected is etched easily drug, it is not necessary to use a lift-off method to form the light output opening of the electrode. Therefore, it is possible to reliably process the electrode with good yield and dimensional accuracy while maintaining the function of the contact layer, thereby providing a stable surface emitting laser with good yield without deteriorating the laser characteristics.

  According to the fourth and fifth aspects of the present invention, the lower mirror, the resonator layer composed of a plurality of semiconductor layers including the semiconductor active layer, and the upper mirror are sequentially laminated on the semiconductor substrate, and the uppermost surface of the upper mirror is formed. Alternatively, the upper electrode is connected to the upper contact layer made of any semiconductor layer between the uppermost surface of the upper mirror and the active layer, and the lower contact made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. In a surface-emitting laser element in which a lower electrode is connected to a layer, an opening for light output is provided in either the upper electrode or the lower electrode, and no contact is made between the electrode and the contact layer to which the electrode is connected. Since the alloy ohmic contact is formed, the selection range of the electrode material is further expanded. Therefore, a surface emitting laser can be provided more easily, with a good yield, and stably.

Particularly, in the invention according to claim 5, in the surface emitting laser element according to claim 4, the electrode on which the non-alloy ohmic contact is formed is Al, Ti, Cr, Si, Cu, Ta, Zr, Zn, Bi, Sb, Sn, Hg, Fe, Co, Mg, Be, or an alloy containing them as a main component, the contact layer to which the electrode is connected is GaAs, and the impurity concentration of the contact layer is 1. Since it is 0 × 10 ²⁰ cm ⁻³ or more and the contact layer is highly doped to 1.0 × 10 ²⁰ cm ⁻³ or more, a better ohmic contact can be obtained. A surface emitting laser element having a lower resistance can be obtained.

  Further, according to the invention of claim 6, since the structure is such that the GaInNAs-based material is provided in the active layer and the electrode portion can be formed with a simple process with a high yield, the temperature characteristic of the oscillation wavelength having good consistency with the silica-based fiber is obtained. A GaInNAs surface emitting laser element having a good and simple element structure can be obtained at a lower cost. That is, it is possible to provide a surface emitting laser element that can be manufactured at low cost, has high adaptability for optical transmission, has good temperature characteristics, and high reliability.

  According to the seventh aspect of the present invention, since the surface emitting laser elements according to any one of the third to sixth aspects are arranged in an array on the semiconductor substrate, the conventional element is changed. An array light source for parallel transmission and an array light source for writing can be obtained at lower cost than the array used.

According to the invention described in claim 8, since the optical transmission system is configured by using the surface emitting laser element or the surface emitting laser array according to the present invention, the optical transmission system having a large capacity and a high speed at a lower cost. Can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described.

(First form)
In the first embodiment of the present invention, a lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on a semiconductor substrate, and activated from the upper mirror upper surface or the upper mirror upper surface. The upper electrode is connected to the upper contact layer made of any semiconductor layer between the layers, and the lower electrode is connected to the lower contact layer made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. In the method of manufacturing the surface emitting laser element, after forming at least one of the upper electrode and the lower electrode on the corresponding contact layer, a part of the electrode is removed by a wet etching method and the light output opening It is characterized by forming.

  Here, for example, a compound semiconductor substrate such as GaAs, InP, or GaP is used as the semiconductor substrate. The lower mirror is preferably a semiconductor DBR such as AlAs / GaAs, AlGaAs / GaAs, GaInP / GaAs, AlGaN / GaN, GaInAsP / InP, and AlGaInAs / InP that can be satisfactorily grown on these substrates. Further, the resonator layer has a structure in which lower and upper spacer layers such as GaAs and InP are provided and an active layer is provided between these spacer layers.

  Here, the active layer is selected according to the substrate, and examples of combinations of the active layer and the substrate (active layer-substrate) include GaInAsP-InP (1.3 μm band, 1.55 μm band), GaInNAs-GaAs (1.3 μm band). , 1.55 μm band), GaInAs-GaAs (0.98 μm band), GaAlAs-GaAs (0.85 μm band), AlGaInP-GaAs (0.65 μm band), and the like.

  Further, the two spacer layers function to transport carriers to the active layer and to form a resonator, and are required to be transparent to light to be emitted. It is selected from GaAs, InP, GaInAsP, GaAlAs, AlGaInP, GaInP and the like depending on the substrate and the active layer material.

The upper mirror is formed of a semiconductor DBR or a dielectric DBR. Examples of the semiconductor DBR include AlAs / GaAs, AlGaAs / GaAs, GaInP / GaAs, AlGaN / GaN, GaInAsP / InP, and AlGaInAs / InP. Examples of the dielectric DBR include ZrO ₂ / SiO ₂ , MgO / SiO ₂ , MgO / Si, Al ₂ O ₃ / MgF _{2 and the} like.

  The substrate, the upper and lower DBRs, and the upper and lower spacer layers may be positively or negatively doped as necessary to transport positive and negative carriers to the active layer.

  The semiconductor laminated film epitaxially grown from the substrate is formed by a method such as MOCVD method or MBE method.

  The semiconductor laminated film is processed so as to form a semiconductor pillar having a bottom surface in the lower spacer layer or the lower DBR by a wet etching method or a dry etching method.

  In this semiconductor pillar, it is preferable to provide a current confinement portion in the vicinity of the active layer in order to reduce the threshold current.

In addition, it is preferable to provide an organic material layer such as polyimide or a semiconductor material layer having a large band gap around the semiconductor pillar in order to protect the element and flatten the upper wiring. Further, it is preferable to cover the entire side surface and bottom surface of the semiconductor pillar with a protective film such as SiO ₂ , SiON, SiN, TiO ₂ , or TiN because the protective effect is enhanced.

  In the present invention, the contact layer is a semiconductor layer other than the active layer that is directly connected to the electrode, and is a layer that serves as a current path between the electrode and the inside of the element. In the present invention, the arrangement of the contact layer is as follows.

  That is, the upper mirror uppermost surface or any semiconductor layer between the uppermost mirror upper surface and the active layer is used as the upper contact layer, and either the semiconductor substrate rear surface or the semiconductor layer between the semiconductor substrate rear surface and the active layer is the lower contact layer. To.

  In the following description, when the lower contact layer is formed of a part of the semiconductor substrate, it is not particularly expressed as the lower contact layer.

  Next, after forming the upper electrode on the upper contact layer, or after forming the lower electrode on the lower contact layer, a part of the upper electrode by a wet etching method using an acid or alkali solution, or A part of the lower electrode is removed to form a light output opening. At the same time, a wiring portion, an element isolation portion, or the like may be formed at the same time.

  Next, a configuration example of the present invention will be described. Note that the order of steps in the manufacturing flow shown in the example is not particularly limited to this order, and can be determined as appropriate depending on the element structure.

(Configuration example 1)
FIG. 3 is a diagram showing a surface emitting laser element according to Structural Example 1 of the present invention. Referring to FIG. 3, on a p-type or n-type conductive semiconductor substrate, a lower semiconductor multilayer mirror (lower semiconductor DBR), a lower spacer layer, an active layer, having the same conductivity as the substrate by MOCVD or MBE, The upper semiconductor DBR having conductivity opposite to that of the upper spacer layer and the lower semiconductor DBR is sequentially grown to form a laminated film. The uppermost layer of the upper semiconductor DBR is doped with an impurity at a high concentration and also serves as an upper contact layer.

  Further, this laminated film is processed into a semiconductor pillar structure (mesa structure) by dry etching or wet etching. In the current confinement portion, when an Al (Ga) As layer is inserted into the laminated film and this layer is oxidized to remove an electric current path to form an insulating region, protons or oxygen ions are brought into the vicinity of the active layer from the laminated film surface. Insulating regions may be formed by implantation.

  Next, a protective layer such as polyimide is provided around the semiconductor pillar.

  Next, an upper electrode having a light output opening is formed. FIG. 4 is a diagram for explaining a process of forming a light output opening in the upper electrode. Referring to FIG. 4, the upper electrode film is formed on the entire surface of the sample including the upper contact layer. Similarly, the lower electrode is provided on the back surface of the conductive semiconductor substrate. Next, a resist is patterned into an electrode pattern shape by a normal lithography process. At this time, there is no resist in a region where the light output opening is to be formed. Thereafter, an etching solution is selected according to the coated metal, and the metal film in the opening formation scheduled region is etched. Subsequently, the resist can be removed to form an upper electrode.

  In the surface emitting laser element of the configuration example 1, current is supplied from each electrode so that carriers of different polarities are injected into the active layer from both sides, thereby causing laser oscillation. In the case of the configuration example 1, the laser oscillation light is output from the opening of the upper electrode.

(Configuration example 2)
FIG. 5 is a view showing a surface emitting laser element according to Configuration Example 2 of the present invention. Referring to FIG. 5, in the configuration example 2, the same laminated film as that in the configuration example 1 is formed, and then the semiconductor pillar structure is processed. In the processing step of the semiconductor pillar structure, processing is performed so that the bottom surface of the etching is in the conductive substrate, the lower semiconductor DBR, or the lower contact layer provided in the lower spacer layer. Next, a current confinement portion is provided as in the configuration example 1. Next, a protective layer such as polyimide is provided on the upper surface of the sample except for the upper surface of the semiconductor pillar and the region where the lower electrode is to be formed.

  An upper electrode film is formed on this sample in a partial region on the upper surface of the sample including the upper contact layer using a metal mask. Similarly, a lower electrode film is formed in a partial region of the upper surface of the sample including the lower contact layer using a metal mask. Next, the resist is patterned into an upper electrode pattern shape and a lower electrode pattern shape by a normal lithography process. At this time, there is no resist in the region where the light output opening is to be formed in the upper electrode pattern. Thereafter, an etching solution is selected according to the coated metal, and the metal film other than the upper electrode pattern and the lower electrode pattern is etched. Subsequently, the resist is removed, and an upper electrode pattern and a lower electrode pattern are formed.

  Also in the surface emitting laser element of the configuration example 2, current is supplied from each electrode to cause laser oscillation. In the case of the configuration example 2, the laser oscillation light is output from the opening of the upper electrode.

(Configuration example 3)
FIG. 6 is a view showing a surface emitting laser element according to Structural Example 3 of the present invention. Referring to FIG. 6, in the configuration example 3, a laminated film similar to that in the configuration example 1 is formed, and subsequently, the semiconductor pillar structure is processed. In the processing step of the semiconductor pillar structure, processing is performed so that the bottom surface of the etching is in the conductive substrate, the lower semiconductor DBR, or the lower contact layer provided in the lower spacer layer. Next, a current confinement portion is provided as in the configuration example 1. Next, a protective layer such as polyimide is provided around the semiconductor pillar.

  On this sample, an upper electrode film is formed on the entire surface of the sample including the upper contact layer. Next, a resist is patterned into an electrode pattern shape by a normal lithography process. Subsequently, the resist is removed and an upper electrode is formed.

  Next, a lower electrode film is formed on the entire back surface of the conductive semiconductor substrate. Next, a resist is patterned into a lower electrode pattern shape by a normal lithography process. At this time, there is no resist in the region where the light output opening is to be formed in the lower electrode pattern. Thereafter, an etching solution is selected according to the coated metal, and the metal film other than the lower electrode pattern is etched. Subsequently, the resist is removed to form a lower electrode pattern.

  In the surface emitting laser element of the configuration example 3, current is supplied from each electrode to cause laser oscillation. In the configuration example 3, the laser oscillation light is output from the opening of the lower electrode.

(Configuration example 4)
FIG. 7 is a view showing a surface emitting laser element according to Structural Example 4 of the present invention. Referring to FIG. 7, the surface emitting laser element of Structural Example 4 is a p-type or n-type conductive semiconductor substrate, and a lower semiconductor multilayer reflector (lower semiconductor) having the same conductivity as the substrate by MOCVD or MBE. DBR), a lower spacer layer, an active layer, an upper spacer layer, and a conductive upper impurity layer having a high impurity concentration opposite to those of the lower semiconductor DBR are sequentially grown to form a laminated film. Further, similarly to the configuration example 1, this laminated film is processed into a semiconductor pillar structure (mesa structure) to form a current confinement portion, and a protective layer such as polyimide is provided. Next, an upper electrode film is formed on the upper contact layer. Subsequently, the resist is patterned into an electrode pattern shape excluding the central portion of the upper contact layer in the upper electrode film portion by ordinary lithography. Thereafter, an etching solution is selected according to the coated metal, and the metal film other than the upper electrode pattern is removed by etching. Next, the resist is removed and an upper electrode is formed. Subsequently, a dielectric DBR is provided so as to cover the opened contact layer by sputtering, EB vapor deposition or CVD.

  Next, the lower electrode is provided on the back surface of the conductive semiconductor substrate.

  Also in the surface emitting laser element of the configuration example 4, current is supplied from each electrode to cause laser oscillation. In the case of the configuration example 4, the laser oscillation light is output from the upper dielectric DBR.

  In the surface emitting laser, in many cases, the upper electrode or the lower electrode having the light output opening portion needs to form a fine pattern, and the opening width or opening diameter of the electrode needs to be several μm to 20 μm. . If it is larger than this range, the drive current path becomes longer and the element resistance increases. On the other hand, if it is smaller than this range, the electrode absorbs part of the output light. Conventionally, these processes have been formed by the lift-off method, which has problems in yield and shape controllability. However, since the electrode opening width is so small, the lift-off method has a limit in yield and large dimensional variation. Therefore, the variation in laser characteristics was also large.

  On the other hand, in the first embodiment of the present invention, since the opening is formed by a normal lithography process that is simple and good in controllability, it is possible to manufacture an element with high yield and stable performance.

(Second form)
According to a second aspect of the present invention, in the method for manufacturing a surface-emitting laser device according to the first aspect, at least one of the upper electrode and the lower electrode is formed on a corresponding contact layer, and then the electrode is formed. A portion of the electrode is removed by a wet etching method using an etchant that easily etches the contact layer and difficult to etch the contact layer, thereby forming a light output opening.

  In a surface emitting laser element having an electrode having a light output opening, a contact layer in contact with the electrode is often provided with a contact layer configured to double as one layer of a semiconductor DBR or a resonator. Therefore, the thickness of the contact layer in the opening needs to have a predetermined optical thickness, and the accuracy of the thickness is a predetermined optical thickness of ± 5 nm or less, preferably a predetermined optical thickness of ± 2 nm. Must be: When it is out of this range, the threshold current becomes extremely high or laser oscillation does not occur.

  When the electrode is opened by etching, the etching solution touches the contact layer after removing the upper electrode.

  Therefore, when the opening is formed by using an etchant that easily etches the electrode and hardly etches the contact layer and uses a wet etching method using the etchant, the contact layer is hardly etched and the opening can be formed.

  Normally, the etching time is set to be longer by 30 seconds to 1 minute than the time for etching all the upper electrodes in consideration of errors. Therefore, it is necessary that the etching rate of the contact layer is small, preferably 10 nm / min or less, preferably 4 nm / min or less is desirable. In this way, when the etching thickness is slightly reduced, a problem such as a decrease in reflectivity can be suppressed by forming the contact layer thicker in advance when forming the contact layer.

  Note that the element configuration to which the manufacturing method of the second embodiment is applied is not limited to the manufacturing examples of the configuration shown in the above-described configuration examples 1, 2, and 4. For example, a manufacturing example like the configuration example 3 Including.

  In the second embodiment of the present invention, the electrode is processed by a wet etching method using an etchant that is difficult to etch the contact layer, so that the function of the contact layer is not deteriorated, the yield is high, and the opening for light output is high in dimensional accuracy. Can be formed. Therefore, an element with high yield and stable performance can be manufactured without deteriorating the laser characteristics.

(Third form)
In the third embodiment of the present invention, a lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on a semiconductor substrate, and activated from the upper mirror upper surface or the upper mirror upper surface. The upper electrode is connected to the upper contact layer made of any semiconductor layer between the layers, and the lower electrode is connected to the lower contact layer made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. In the surface emitting laser device, at least one of the upper electrode and the lower electrode is provided with a light output opening, and the electrode further includes Al, Ti, Cr, Si, Cu, Ta, Zr, Zn, It is made of Bi, Sb, Sn, Hg, Fe, Co, Mg, Be, or an alloy containing them as a main component, and the contact layer to which the electrodes are connected is GaAs. To have.

In the case where GaAs is used for the contact layer, the reactivity of various metal etching solutions with GaAs was examined experimentally in order to investigate the combination of an appropriate electrode material and the etching solution.
As a result, it was found that the following combinations are possible (see Table 1).

  Examples of chemicals that are easy to etch a predetermined metal and difficult to etch GaAs include the following.

Al is etched with a phosphoric acid aqueous solution.
GaAs has a low etching rate in this solution.
Cr, Zn, Bi, Sb, Sn, Hg, Fe, and Co are etched with a hydrochloric acid aqueous solution.
GaAs has a low etching rate in this solution.
Si, Al, Ti, and Cu are etched with a hydrofluoric acid / nitric acid / water mixture.
GaAs has a low etching rate in this solution.
Al, Ti, Ta, Zr, Mg, and Be are etched with a hydrofluoric acid aqueous solution and a hydrofluoric acid buffer.
GaAs has a low etching rate in these solutions.

  Therefore, if these metals are used as electrode materials and the etching liquids listed above are used for the respective electrode materials, selective etching with the GaAs contact layer becomes possible, and electrode openings and electrodes for light output can be obtained. Wiring patterns can be easily formed.

  Examples of the element configuration include the above-described configuration examples 1, 2, 3, and 4.

  Conventionally, Au-based metal has been used as an electrode material. When the light output opening is formed in this electrode, an etching solution or etching gas that does not etch the Au-based metal and etch the semiconductor film is found, and it is formed by a lift-off method having a problem in yield and controllability.

  On the other hand, in the third embodiment of the present invention, since the electrode material is a material that can select a chemical that wet-etches the electrode without etching the contact layer, there is no need to use the lift-off method. Therefore, it is possible to reliably process the electrode with good yield and dimensional accuracy while maintaining the function of the contact layer. Thereby, it is possible to reliably provide a surface emitting laser having a stable characteristic and a good yield without deteriorating the laser characteristic.

(4th form)
In the fourth embodiment of the present invention, a lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on a semiconductor substrate, and activated from the upper mirror upper surface or the upper mirror upper surface. The upper electrode is connected to the upper contact layer made of any semiconductor layer between the layers, and the lower electrode is connected to the lower contact layer made of any semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. In the surface emitting laser device, an optical output opening is provided in either the upper electrode or the lower electrode, and a non-alloy ohmic contact is formed between the electrode and a contact layer to which the electrode is connected. It is characterized by being.

  Here, the non-alloy ohmic contact means that the formation of an alloy is not required at the connection portion between the electrode and the contact layer, and the width of the depletion layer that can be formed into the electrode and the contact layer is reduced by doping the contact layer at a high concentration. This is an ohmic junction that allows carriers to pass through by tunneling. This type is also referred to as a high concentration layer forming ohmic junction.

  Generation of the non-alloy ohmic contact can be confirmed by TEM, micro auger, or the like.

  The electrodes other than the electrodes joined by the non-alloy ohmic contact do not necessarily need to form the non-alloy ohmic contact, and may form a conventional alloy type ohmic contact.

  Examples of the element configuration include the above-described configuration examples 1, 2, 3, and 4.

  In the fourth embodiment of the present invention, since the connection between the electrode and the contact layer takes the form of a non-alloy ohmic contact, the range of selection of the electrode material is further expanded. Therefore, it is possible to more easily form the light output opening with the electrode by the lithography method which is simple and has good controllability. Therefore, it is possible to provide a surface emitting laser element having a stable characteristic more easily, with a good yield.

(5th form)
According to a fifth aspect of the present invention, in the surface emitting laser element according to the fourth aspect, the electrode on which the non-alloy ohmic contact is formed is Al, Ti, Cr, Si, Cu, Ta, Zr, Zn, Bi, It is made of Sb, Sn, Hg, Fe, Co, Mg, Be, or an alloy containing them as a main component. The contact layer to which the electrode is connected is GaAs, and the impurity concentration of the contact layer is 1.0 ×. It is characterized by being 10 ²⁰ cm ⁻³ or more.

  In order to pass a sufficient amount of carriers between the electrode having the non-alloy ohmic contact and the contact layer, the width of the depletion layer at the junction of the contact layer needs to be within a few nm when the laser element is driven. . For this reason, the contact layer needs to be highly doped.

When GaAs is used for the contact layer, the electrodes are Al, Ti, Cr, Si, Cu, Ta, Zr, Zn, Bi, Sb, Sn, Hg, Fe, Co, Mg, Be, or their main components. In the case of the alloy, an ohmic contact can be obtained if the impurity concentration of the contact layer is 1.0 × 10 ²⁰ cm ⁻³ or more regardless of the conductivity type. If the concentration is less than this, ohmic contact may not be obtained.

In the fifth embodiment, since the contact layer is highly doped to 1.0 × 10 ²⁰ cm ⁻³ or more, the width of the depletion layer at the junction is narrowed, and tunneling of carriers is facilitated. Good ohmic contact can be obtained. Therefore, a lower resistance element can be obtained.

(Sixth form)
According to a sixth aspect of the present invention, in the surface emitting laser element according to any one of the third to fifth aspects, the active layer includes a layer made of a GaInNAs-based material.

  The GaInNAs-based material is composed of a III-V group mixed crystal semiconductor containing N and As, specifically, GaAsN, GaInNAs, GaAsNSb, GaInNAsSb, GaInNAsP, and the like.

  One or a plurality of well layers made of these GaInNAs-based materials having a thickness of several tens of nm or less are surrounded by a semiconductor well layer made of GaAs, GaInP, AlGaAs or the like having a larger band gap than the well layer material. It is preferred to provide a layer.

  A laser using a GaInNAs-based material in a long wavelength band (for example, a wavelength band of 1.1 μm or more), which has started rapidly in recent years, has an oscillation wavelength of a long wavelength band, so it matches with a silica-based fiber. High nature.

  Furthermore, since it can be formed on a GaAs substrate, a wide bandgap material can be selected for a layer around the active layer such as a spacer layer, carrier confinement is improved, and temperature characteristics are high. For this reason, unlike the case of the conventional long wavelength band laser which uses GaInAsP formed on an InP substrate as an active layer, no cooling device is required.

Furthermore, since a surface emitting laser using this material for the active layer can be formed on a GaAs substrate, Al (Ga) As / GaAs having a large refractive index difference that can be formed on the GaAs substrate, more broadly, Al _x Ga _{( 1-x) as / Al y} Ga (1-y) as a (0 ≦ y <x ≦ 1 ) is used as the semiconductor DBR is suitable. Therefore, a surface emitting laser having a semiconductor DBR with a small number of layers can be obtained.

  Thus, since the GaInNAs surface emitting laser has excellent characteristics, it is suitable as a light emitting element in optical communication systems, between computers, between chips, in-chip optical interconnection, and in optical computing.

  Thus, in the sixth embodiment of the present invention, the active layer includes a layer made of a GaInNAs-based material, and the electrode can be formed with a high yield with a simple process. A GaInNAs surface emitting laser element with good temperature characteristics and a simple element configuration can be obtained at a lower cost.

(7th form)
A seventh aspect of the present invention is a surface emitting laser array in which a plurality of surface emitting laser elements of any one of the third to sixth aspects are arranged in an array on a semiconductor substrate.

  As described above, the surface-emitting laser can easily produce a large number of elements on a single substrate and does not require cleavage, so that parallelization and two-dimensional high-density array can be easily performed.

  In the seventh embodiment, since the surface emitting laser elements of the present invention are arranged one-dimensionally or two-dimensionally, the array light source for parallel transmission or writing can be performed at a lower cost than an array using conventional elements. An array light source for dust is obtained.

(8th form)
The eighth aspect of the present invention is an optical transmission system in which the surface emitting laser element of any one of the third to sixth forms or the surface emitting laser array of the seventh form is used.

  8 and 9 are diagrams showing a configuration example of an optical transmission system using the surface emitting laser element of the present invention as a light source.

  In the example of FIG. 8, the optical transmission system is configured as a parallel transmission system, and signals from the surface emitting laser element are transmitted simultaneously using a plurality of fibers.

  Further, in the example of FIG. 9, the optical transmission system is configured as a multi-wavelength transmission system, and optical signals from a plurality of light emitting elements having different oscillation wavelengths are respectively introduced into an optical multiplexer via optical fibers and multiplexed. A single optical fiber is introduced and transmitted, and the transmitted optical signal is separated into a plurality of optical signals having different original wavelengths through an optical demultiplexer connected to a transmission destination device. A plurality of light receiving elements are reached.

  In the eighth embodiment, since the optical transmission system is configured by using the surface emitting laser element or the array of the present invention, a large-capacity and high-speed optical transmission system can be obtained at a lower cost.

FIG. 10 is a diagram showing the surface emitting laser element of Example 1. In Example 1, a p-AlGaAs / p-GaAs lower DBR composed of 28.5 pairs of p-AlGaAs / n-GaAs, a p-GaAs lower spacer layer, on a p-type GaAs (100) substrate by MOCVD. Growing a GaInAs / GaAs triple quantum well active layer, an n-GaAs upper spacer layer including an AlAs selective oxide layer in the layer, and an n-AlGaAs / n-GaAs upper DBR comprising 23 pairs of n-AlGaAs / n-GaAs; A laminated film is produced. Then, Se is added to the uppermost GaAs layer of the upper DBR by 1.0 × 10 ²⁰ cm ^{−3 so} that it also serves as the upper contact layer.

A photoresist mask pattern is formed on the contact layer by a photolithography process, and semiconductor pillars are formed by dry etching using Cl ₂ gas. The lower part of the semiconductor pillar is in the lower DBR. Subsequently, the mask pattern is removed.

Next, the AlAs selective oxidation layer is oxidized with H ₂ O vapor at 400 ° C. leaving a 25 μm ² AlAs layer, and a current confinement structure is produced.

  Next, after applying a photosensitive polyimide precursor and removing the polyimide precursor in a region where the edge of the contact layer on the upper surface of the semiconductor pillar is left by photolithography, curing is performed to form a polyimide protective film.

Next, after depositing an AuZn / Au lower electrode on the back of the sample, alloying is performed at 400 ° C. in an N ₂ atmosphere.

Next, an Al film is deposited to a thickness of 200 nm on the entire surface of the sample. Thereafter, patterning is performed so that the upper electrode region of the upper portion of the semiconductor pillar other than the light output portion is covered with a resist. Next, the sample is dipped in H ₃ PO ₄ —H ₂ O (2: 1) to form an upper electrode having an opening. Finally, heat treatment is performed at 250 ° C. in an N ₂ atmosphere in order to stabilize the bonding between the upper electrode and the contact layer.

  Through the above process, a 0.98 μm band surface emitting laser element is obtained. The p-side electrode is positive and the n-side electrode is negative, and a current is passed to obtain light output from the electrode opening.

In the first embodiment, since Al is used for the upper electrode, the electrode opening can be obtained with high dimensional accuracy by a simple process without using the lift-off method. Further, since the contact layer is doped at a high concentration, a good non-alloy ohmic contact can be obtained. When the doping amount of the GaAs upper contact layer is less than 1.0 × 10 ²⁰ cm ⁻³ cm ⁻³ , ohmic characteristics may not be obtained at the junction.

FIG. 11 is a diagram showing a surface emitting laser element of Example 2. In Example 2, an MBE method is used to form an n-AlGaAs / n-GaAs lower DBR composed of 28.5 pairs of n-AlGaAs / n-GaAs, a GaAs lower spacer layer, a GaInNAs / A GaAs triple quantum well active layer and a GaAs upper spacer layer including an AlAs selective oxide layer in the layer are sequentially grown to form a laminated film. Then, Zn is doped in the vicinity of the uppermost surface of the GaAs upper spacer layer by 2.0 × 10 ²⁰ cm ^{−3 so} that it also serves as the upper contact layer.

A photoresist mask pattern is formed on the contact layer by a photolithography process, and semiconductor pillars are formed by dry etching using Cl ₂ gas. The lower part of the semiconductor pillar is in the lower DBR. Subsequently, the mask pattern is removed.

Next, the AlAs selective oxidation layer is oxidized with H ₂ O vapor at 400 ° C. leaving a 25 μm ² AlAs layer, and a current confinement structure is produced.

  Next, after applying a photosensitive polyimide precursor and removing the polyimide precursor in a region where the edge of the contact layer on the upper surface of the semiconductor pillar is left by photolithography, curing is performed to form a polyimide protective film.

Next, after depositing an AuGe / Ni / Au lower electrode on the back of the sample, alloying is performed at 400 ° C. in an N ₂ atmosphere.

Next, a Cr film is deposited to a thickness of 200 nm on the entire surface of the sample. Thereafter, patterning is performed so that the upper electrode region of the upper portion of the semiconductor pillar other than the light output portion is covered with a resist. Next, the sample is dipped in HCl-H ₂ O (1: 1) to form an upper electrode having an opening. Subsequently, heat treatment is performed at 250 ° C. in an N ₂ atmosphere in order to stabilize the bonding between the upper electrode and the contact layer.

After the surface other than the semiconductor pillar is covered with a photoresist film, an upper dielectric DBR composed of 8 pairs of SiO ₂ / ZrO ₂ is formed by electron beam evaporation. This photoresist film is dissolved with an organic solvent to remove the excess dielectric film.

  By the above process, a 1.3 μm band surface emitting laser element is obtained. The p-side electrode is positive and the n-side electrode is negative, and a current is passed to obtain light output from the electrode opening.

In Example 2, since Cr is used for the upper electrode, an electrode opening can be obtained with high dimensional accuracy by a simple process without using the lift-off method. Further, since the contact layer is doped at a high concentration, a good non-alloy ohmic contact can be obtained. When the doping amount of the upper contact layer is less than 1.0 × 10 ²⁰ cm ⁻³ , ohmic characteristics may not be obtained at the junction.

FIG. 12 is a diagram showing a surface emitting laser element according to Example 3. In Example 3, a lower DBR made of 35.5 pairs of p-AlGaAs / p-GaAs, a GaAs lower spacer layer, a GaInNAs / GaAs double quantum well active layer on a p-type GaAs (100) substrate by MOCVD. Then, a GaAs upper spacer layer, an AlAs selective oxide layer, and an n-AlGaAs / n-GaAs upper DBR composed of 28.5 pairs of n-AlGaAs / n-GaAs are grown to produce a laminated film. The uppermost GaAs layer of the upper DBR is configured to serve as a contact layer by doping Se with 1.5 × 10 ²⁰ cm ⁻³ .

Subsequently, a photoresist mask pattern is formed on the contact layer by a photolithography process, and dry etching using Cl ₂ gas is performed to form semiconductor pillars. The lower part of the semiconductor pillar is in the lower DBR. Subsequently, the mask pattern is removed.

Next, the AlAs selective oxidation layer is oxidized with H ₂ O vapor at 400 ° C. leaving a 25 μm ² AlAs layer, and a current confinement structure is produced.

  Next, after applying a photosensitive polyimide precursor and removing the polyimide precursor in a region where the edge of the contact layer on the upper surface of the semiconductor pillar is left by photolithography, curing is performed to form a polyimide protective film.

Next, after depositing an AuZn / Au lower electrode on the back of the sample, alloying is performed at 400 ° C. in an N ₂ atmosphere.

Next, a Ti film is deposited on the entire surface of the sample to a thickness of 50 nm, and an Al film is sequentially deposited to a thickness of 200 nm. Thereafter, patterning is performed so that the upper electrode region of the upper portion of the semiconductor pillar other than the light output portion is covered with a resist. Next, the sample is dipped in HF—H ₂ O (1: 7) to form an upper electrode having an opening. Subsequently, heat treatment is performed at 250 ° C. in an N ₂ atmosphere in order to stabilize the bonding between the upper electrode and the contact layer.

  By the above process, a 1.3 μm band surface emitting laser element is obtained. The p-side electrode is positive and the n-side electrode is negative, and a current is passed to obtain light output from the electrode opening.

Since an Al / Ti film is used for the upper electrode, an electrode opening can be obtained with high dimensional accuracy by a simple process without using the lift-off method. Further, since the contact layer is doped at a high concentration, a good non-alloy ohmic contact can be obtained. If the doping amount of the GaAs upper contact layer is less than 1.0 × 10 ²⁰ cm ⁻³ , ohmic characteristics may not be obtained at the junction.

FIG. 13 is a diagram showing a surface emitting laser element according to Example 4. In Example 4, a laminated film having the same configuration as that of Example 3 is formed. However, the uppermost GaAs layer of the upper DBR is doped with Se by 2.5 × 10 ²⁰ cm ^{−3 so} that it also serves as a contact layer. One GaAs layer in the lower DBR is doped with 1.0 × 10 ²⁰ cm ^{−3 of} Zn so that a lower contact layer can be formed later. Next, a semiconductor pillar structure, a current confinement portion, and a polyimide protective film are formed as in the third embodiment. However, the lower part of the semiconductor pillar is located in the lower contact layer. Further, the polyimide protective film pattern is formed so that a part of the bottom surface of the semiconductor pillar formed of one layer in the lower DBR is opened in addition to the upper face of the semiconductor pillar. Note that the opening region at the bottom of the semiconductor pillar includes a region for forming the lower electrode.

Next, a Ti film is deposited on the entire surface of the sample to a thickness of 50 nm, and an Al film is sequentially deposited to a thickness of 200 nm. Thereafter, an upper electrode pattern and a lower electrode pattern of portions other than the light output portion on the upper surface of the semiconductor pillar are formed with a resist. Next, the sample is dipped in HF—H ₂ O (1: 7) to form an upper electrode and a lower electrode having openings. Subsequently, heat treatment is performed at 250 ° C. in an N ₂ atmosphere in order to stabilize the bonding between the two electrodes and the contact layer.

  By the above process, a 1.3 μm band surface emitting laser element is obtained. A current is passed with the p-side electrode being positive and the n-side electrode being negative, and light output is obtained from the upper electrode opening.

In Example 4, since the Al / Ti film is used for the two electrodes, the electrode opening and the electrode pattern can be obtained with high dimensional accuracy by a simple process without using the lift-off method. Further, since the upper and lower contact layers are doped at a high concentration, a good non-alloy ohmic contact can be obtained. If the doping amount of the GaAs upper contact layer is less than 1.0 × 10 ²⁰ cm ⁻³ , ohmic characteristics may not be obtained at the junction.

It is a figure which shows an example of the conventional surface emitting laser element. It is a figure which shows an example of the conventional surface emitting laser element. It is a figure which shows the surface emitting laser element of the structural example 1 of this invention. It is a figure for demonstrating the process of forming the opening part for light output in an upper electrode. It is a figure which shows the surface emitting laser element of the structural example 2 of this invention. It is a figure which shows the surface emitting laser element of the structural example 3 of this invention. It is a figure which shows the surface emitting laser element of the structural example 4 of this invention. It is a figure which shows the structural example of the optical transmission system which used the surface emitting laser element of this invention as a light source. It is a figure which shows the structural example of the optical transmission system which used the surface emitting laser element of this invention as a light source. 1 is a diagram illustrating a surface emitting laser element of Example 1. FIG. 6 is a view showing a surface emitting laser element according to Example 2. FIG. 6 is a view showing a surface emitting laser element according to Example 3. FIG. 6 is a view showing a surface emitting laser element of Example 4. FIG.

Claims (8)

On the semiconductor substrate, a lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked, and either the upper mirror upper surface or the semiconductor layer between the upper mirror upper surface and the active layer In the manufacturing method of the surface emitting laser device, the upper electrode is connected to the upper contact layer made of, and the lower electrode is connected to the lower contact layer made of the semiconductor layer between the semiconductor substrate back surface or the semiconductor substrate back surface and the active layer. A surface characterized in that after forming at least one of the upper electrode and the lower electrode on the corresponding contact layer, a part of the electrode is removed by a wet etching method to form a light output opening. A method for manufacturing a light emitting laser element. 2. The method of manufacturing a surface emitting laser device according to claim 1, wherein at least one of the upper electrode and the lower electrode is formed on the corresponding contact layer, and then the electrode is easily etched and the contact layer is difficult to etch. A method for manufacturing a surface-emitting laser element, wherein a part of the electrode is removed by wet etching using a liquid to form an opening for light output. A lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on the semiconductor substrate, and either the upper mirror upper surface or the upper mirror upper surface to the active layer between the active layers In the surface emitting laser device, the upper electrode is connected to the upper contact layer made of, and the lower electrode is connected to the lower contact layer made of the semiconductor layer on the semiconductor substrate back surface or between the semiconductor substrate back surface and the active layer. Alternatively, an optical output opening is formed in at least one of the lower electrodes, and the electrode further includes Al, Ti, Cr, Si, Cu, Ta, Zr, Zn, Bi, Sb, Sn, Hg, and Fe. A surface emitting laser element comprising: Co, Mg, Be, or an alloy containing them as a main component, and a contact layer to which the electrode is connected is GaAs. A lower mirror, a resonator layer composed of a plurality of semiconductor layers including a semiconductor active layer, and an upper mirror are sequentially stacked on the semiconductor substrate, and either the upper mirror upper surface or the upper mirror upper surface to the active layer between the active layers In the surface emitting laser device, the upper electrode is connected to the upper contact layer made of, and the lower electrode is connected to the lower contact layer made of the semiconductor layer on the semiconductor substrate back surface or between the semiconductor substrate back surface and the active layer. A surface emitting laser comprising: a light output opening provided in any one of the lower electrodes; and a non-alloy ohmic contact formed between the electrode and a contact layer to which the electrode is connected element. 5. The surface emitting laser element according to claim 4, wherein the electrode on which the non-alloy ohmic contact is formed is Al, Ti, Cr, Si, Cu, Ta, Zr, Zn, Bi, Sb, Sn, Hg, Fe, It is made of Co, Mg, Be, or an alloy containing them as a main component, the contact layer to which the electrode is connected is GaAs, and the impurity concentration of the contact layer is 1.0 × 10 ²⁰ cm ⁻³ or more. A surface emitting laser element characterized by the above. 6. The surface emitting laser element according to claim 3, wherein the active layer includes a layer made of a GaInNAs-based material. 7. A surface-emitting laser array, wherein a plurality of the surface-emitting laser elements according to claim 3 are arranged in an array on a semiconductor substrate. An optical transmission system, wherein the surface-emitting laser element according to any one of claims 3 to 6 or the surface-emitting laser array according to claim 7 is used.

Images