WO2021193375A1

WO2021193375A1 - Surface-emitting laser

Info

Publication number: WO2021193375A1
Application number: PCT/JP2021/011205
Authority: WO
Inventors: 高橋　義彦
Original assignee: ソニーセミコンダクタソリューションズ株式会社
Priority date: 2020-03-26
Filing date: 2021-03-18
Publication date: 2021-09-30
Also published as: JPWO2021193375A1

Abstract

An embodiment of the present disclosure relates to a surface-emitting laser comprising a substrate and a mesa portion formed by an epitaxial crystal growth process using the substrate as a crystal growth substrate, the mesa portion including, in this order, a DBR layer of a first conductivity type, an active layer, a DBR layer of a second conductivity type, and a contact layer of the second conductivity type. The surface-emitting laser is further provided with a first electrode layer adjoining the substrate, and a second electrode layer adjoining the contact layer of the second conductivity type. The substrate includes a diffusion region of the first conductivity type having a relatively high concentration of an impurity of the first conductivity type and extending at least from a region opposing an outer edge of the mesa portion to a region at the foot of the mesa portion. The first electrode layer adjoins the diffusion region of the first conductivity type.

Description

Surface emitting laser

This disclosure relates to a surface emitting laser.

Surface emitting lasers that emit light in the normal direction of the substrate are known (for example, Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2005-93634 Japanese Unexamined Patent Publication No. 10-209565 JP-A-2015-41627

By the way, in a surface emitting laser, a contact layer may be provided between the substrate and the substrate side DBR as an energizing path from the electrode to the substrate side DBR (distributed Bragg reflector). In this case, the contact layer is responsible for both reducing the contact resistance between the electrode and the substrate-side DBR and transporting the carrier from the electrode into the substrate-side DBR. Therefore, light absorption due to impurities in the contact layer occurs. Although it is possible to reduce the light absorption by thinning the contact layer, in such a case, the resistance value of the contact layer rises, so that the drive voltage rises. Therefore, it is desirable to provide a surface emitting laser capable of achieving both a high light output and a low drive voltage.

The surface emitting laser according to the embodiment of the present disclosure is formed by a substrate and an epitaxial crystal growth method using the substrate as a crystal growth substrate, and has a first conductive DBR layer, an active layer, a second conductive DBR layer, and a second. A mesa portion including a conductive contact layer in this order is provided. The surface emitting laser further includes a first electrode layer in contact with the substrate and a second electrode layer in contact with the second conductive contact layer. The substrate has a first conductive diffusion region in which the concentration of impurities of the first conductive type is relatively high, at least from a region facing the outer edge of the mesa portion to a region at the base of the mesa portion, and the first electrode layer is a first electrode layer. 1 It is in contact with the conductive diffusion region.

In the surface emitting laser according to the embodiment of the present disclosure, at least from the region facing the outer edge of the mesa portion to the region of the skirt of the mesa portion, the first conductive type diffusion region having a relatively high concentration of the first conductive type impurities is formed. Formed on the substrate, the first electrode layer is in contact with the first conductive diffusion region. As a result, the first conductive diffusion region functions as an energization path from the first electrode layer to the first conductive DBR layer. At this time, by forming the first conductive diffusion region in a region of the surface on the mesa portion side excluding at least the region facing the center of the mesa portion, light absorption by impurities in the first conductive diffusion region is achieved. It can be suppressed. Further, even when the first conductive diffusion region is formed in the region of the surface on the mesa portion side facing the center of the mesa portion, the first conductive diffusion region faces the center of the mesa portion. By making the impurity concentration in the region to be squeezed sufficiently lower than the impurity concentration in the region facing the outer edge of the mesa portion, it is possible to suppress light absorption by impurities in the first conductive diffusion region.

It is a figure which shows the cross-sectional composition example of the surface emitting laser which concerns on 1st Embodiment of this disclosure. It is a figure which shows an example of the manufacturing process of the surface emitting laser of FIG. It is a figure which shows an example of the manufacturing process following FIG. It is a figure which shows an example of the manufacturing process following FIG. It is a figure which shows an example of the manufacturing process following FIG. It is a figure which shows an example of the manufacturing process following FIG. It is a figure which shows an example of the manufacturing process following FIG. It is a figure which shows the cross-sectional composition example of the surface emitting laser array which concerns on 2nd Embodiment of this disclosure. It is a figure which shows the top surface composition example of the surface emitting laser of FIG.

Hereinafter, the mode for carrying out the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following aspects. Further, the present disclosure is not limited to the arrangement, dimensions, dimensional ratio, etc. of each component shown in each figure.

<First Embodiment>
[composition]
The surface emitting laser 1 according to the first embodiment of the present disclosure will be described. FIG. 1 shows an example of cross-sectional configuration of the surface emitting laser 1.

The surface emitting laser 1 includes a vertical resonator on the substrate 10. The vertical resonator is configured to oscillate at an _{oscillation wavelength of λ 0} by two DBR (distributed Bragg reflector) layers (p-type DBR layer 21, n-type DBR layer 25) facing each other in the normal direction of the substrate 10. There is. The p-type DBR layer 21 corresponds to a specific example of the “first conductive DBR layer” of the present disclosure. The n-type DBR layer 25 corresponds to a specific example of the “second conductive DBR layer” of the present disclosure. The p-type DBR layer 21 is formed at a position closer to the substrate 10 than the n-type DBR layer 25. The n-type DBR layer 25 is formed at a position distant from the substrate 10 as compared with the p-type DBR layer 21. The surface emitting laser 1 is configured so that the laser beam L is emitted from the p-type DBR layer 21 side. Therefore, the surface emitting laser 1 is a back surface emitting type laser having a light emitting surface 1S of laser light L on the back surface.

The surface emitting laser 1 includes an epitaxial laminated structure 20 formed on a substrate 10 by an epitaxial crystal growth method using the substrate 10 as a crystal growth substrate. The epitaxial laminated structure 20 includes, for example, a p-type DBR layer 21, a spacer layer 22, an active layer 23, a spacer layer 24, an n-type DBR layer 25, and an n-type contact layer 26 in this order from the substrate 10 side. There is. In the epitaxial laminated structure 20, the p-type DBR layer 21, the spacer layer 22, the active layer 23, the spacer layer 24, the n-type DBR layer 25, and the n-type contact layer 26 are columnar mesas extending in the normal direction of the substrate 10. It constitutes a part 20A.

The surface emitting laser 1 includes an electrode layer 32 in contact with the top of the mesa portion 20A (that is, the n-type contact layer 26), and the electrode layer 31 in contact with the p-type diffusion region 11 (described later) extending to the skirt of the mesa portion 20A. It has. The n-type contact layer 26 is a layer for ohmic contacting the n-type DBR layer 25 and the electrode layer 32 with each other. The p-type diffusion region 11 is formed on the surface of the substrate 10. The p-type diffusion region 11 is formed in the substrate 10 from at least a region facing the outer edge of the mesa portion 20A to a region at the base of the mesa portion 20A. The p-type diffusion region 11 is formed in a region of the substrate 10 on the mesa portion 20A side, excluding at least a region facing the center of the mesa portion 20A. The electrode layer 31 is in contact with the skirt region of the mesa portion 20A on the surface of the p-type diffusion region 11. The p-type diffusion region 11 is an energization path between the electrode layer 31 and the mesa portion 20A. The electrode layer 32 is formed at least at a position facing the light emitting region of the active layer 23. The electrode layer 32 corresponds to a specific example of the “second electrode layer” of the present disclosure. The electrode layer 31 corresponds to a specific example of the “first electrode layer” of the present disclosure.

The surface emitting laser 1 is formed of, for example, an arsenic semiconductor. The arsenic semiconductor refers to a compound semiconductor containing an arsenic (As) element and at least one of aluminum (Al), gallium (Ga), and indium (In). The substrate 10 is, for example, a semi-insulating semiconductor substrate. Examples of the semi-insulating semiconductor substrate that can be used for the substrate 10 include a GaAs substrate. The substrate 10 may be a low-doped p-type semiconductor substrate. Examples of the low-doped p-type semiconductor substrate that can be used for the substrate 10 include a GaAs substrate having ^{a p-type impurity concentration of 1 × 10 16} cm ^{-3 or less.} When the substrate 10 is a semi-insulating semiconductor substrate or a low-doped p-type semiconductor substrate, the p-type diffusion region 11 is the p-type impurity concentration (p-type impurity concentration in the unformed region of the p-type diffusion region 11) in the substrate 10. For example, the ^{p-type impurity concentration is higher than 1 × 10 16} cm ^-3 or less (for example, 1 × 10 ¹⁸ cm ^-3 or more). The p-type diffusion region 11 is formed, for example, in the substrate 10 from the surface of the substrate 10 to a region having a depth of 300 nm or more.

The p-type DBR layer 21 is formed by alternately laminating low refractive index layers (not shown) and high refractive index layers (not shown). In the p-type DBR layer 21, the low refractive index layer is composed of, for example, p-type Al _x1 Ga _1-x1 As (0 <x1 <1) having an _{optical thickness of λ 0} × 1/4 (λ _{0 is the oscillation wavelength).} The high refractive index layer is composed of, for example, p-type Al _x2 Ga _1-x2 As (0 ≦ x2 <x1) _{having an optical thickness of λ 0 × 1/4.} The spacer layer 22 is made of, for example, p-type Al _x3 Ga _1-x3 As (0 ≦ x3 <1). Examples of the p-type impurities in the p-type DBR layer 21 and the spacer layer 22 include carbon (C).

The active layer 23 includes, for example, _{a well layer (not shown) composed of undoped In x4} Ga _1-x4 As or Al _x4 Ga _1-x4 As (0 ≦ x4 <1) and undoped In _x5 Ga _1-x5 As. Alternatively, it has a multiple quantum well structure in which barrier layers (not shown) composed of Al _x5 Ga _{1-x5 As (0 ≦ x4 <x5) are alternately laminated.} The region of the active layer 23 facing the current injection region 27B (described later) is the light emitting region.

The spacer layer 24 is made of, for example, n-type Al _x6 Ga _1-x6 As (0 ≦ x6 <1). The n-type DBR layer 25 is formed by alternately laminating low refractive index layers (not shown) and high refractive index layers (not shown). In the n-type DBR layer 25, the low refractive index layer is composed of, for example, n-type Al _x7 Ga _1-x7 _{As (0 <x7 <1) having an optical thickness of λ 0} × 1/4, and the high refractive index layer is, for example, optical. It is composed of n-type Al _x8 Ga _1-x8 As (0 ≦ x8 <x7) having a thickness of λ _{0 × 1/4.} The n-type DBR layer 25 is configured to have a large reflectance with respect to _{the oscillation wavelength λ 0} of the vertical resonator in the mesa portion 20A as compared with the p-type DBR layer 21. The n-type DBR layer 25 is formed thicker than, for example, the p-type DBR layer 21. The n-type contact layer 26 is composed of, for example, n-type Al _x9 Ga _1-x9 As (0 ≦ x9 <1). Examples of the n-type impurities in the spacer layer 24, the n-type DBR layer 25 and the n-type contact layer 26 include silicon (Si).

The epitaxial laminated structure 20 has a current constriction layer 27 in the p-type DBR layer 21 or between the p-type DBR layer 21 and the spacer layer 24. The current constriction layer 27 has a current injection region 27B and a current constriction region 27A. The current constriction region 27A is formed in a peripheral region of the current injection region 27B. The current injection region 27B is composed of, for example, p-type Al _x10 Ga _1-x10 As (0 <x10 ≦ 1). The current constriction region 27A is composed of, for example, Al ₂ O ₃ (aluminum oxide), and can be obtained, for example, by oxidizing a high concentration of Al contained in the oxidized layer 27D (described later) from the side surface. .. Therefore, the current constriction layer 27 has a function of constricting the current.

The electrode layer 31 is in contact with the surface of the p-type diffusion region 11 on the mesa portion 20A side. The electrode layer 31 is made of a non-alloy, and is, for example, a laminated body formed by laminating Ti, Pt, and Au in order from the substrate 10 (p-type diffusion region 11) side. The electrode layer 32 is composed of an alloy, and is, for example, a laminated body formed by laminating AuGe, Ni, and Au in order from the n-type contact layer 26 side. An insulating layer 33 is formed around the mesa portion 20A. The insulating layer 33 is a layer for protecting the mesa portion 20A, and is composed of, for example, _{a laminated body in which SiO 2} , Si, and SiO ₂ are laminated in this order.

[Production method]
Next, a method for manufacturing the surface emitting laser 1 according to the present embodiment will be described. 2 to 7 show an example of a manufacturing procedure of the surface emitting laser 1.

_{First, a mask dielectric film such as SiO 2} or SiN was formed on a substrate 10 (for example, a semi-insulating semiconductor substrate or a low-doped p-type semiconductor substrate), and a circular resist layer was formed on the dielectric film for masking. After that, the dielectric film is etched to form the mask layer 110 when the impurities are diffused (FIG. 2). Next, by using the mask layer 110 as a mask and performing impurity diffusion, a p-type diffusion region 11 is formed on the surface of the substrate 10 in a region not covered with the mask layer 110 (FIG. 3). After that, the mask layer 110 is removed.

Next, compound semiconductors are collectively formed on the substrate 10 on which the p-type diffusion region 11 is formed by an epitaxial crystal growth method such as a MOCVD (Metal Organic Chemical Vapor Deposition) method. At this time, as raw materials for the compound semiconductor, for example, methylaluminum (TMAl), trimethylgallium (TMGa), trimethylindium (TMIn) and other methyl-based organometallic gases and arsine (AsH ₃ ) gas are used, and donor impurities are used. As a raw material, for example, disilane (Si ₂ H ₆ ) is used, and as a raw material for acceptor impurities, for example, carbon tetrabromide (CBr ₄ ) is used.

Epitaxy containing a p-type DBR layer 21, a spacer layer 22, an active layer 23, a spacer layer 24, an n-type DBR layer 25, and an n-type contact layer 26 on the surface of the substrate 10 by an epitaxial crystal growth method such as the MOCVD method. The laminated structure 20 is formed (FIG. 4). At this time, another layer such as a buffer layer may be formed between the substrate 10 and the p-type DBR layer 21.

Next, for example, a circular resist layer 120 is formed on the epitaxial laminated structure 20 (FIG. 5). At this time, the resist layer 120 is formed at a size and position on the surface of the substrate 10 so as to cover at least the unformed region of the p-type diffusion region 11 when viewed in a plan view. Subsequently, the epitaxial laminated structure 20 is selectively etched using the resist layer 120 as a mask, and the epitaxial laminated structure 20 is etched to a depth reaching the substrate (p-type diffusion region 11). At this time, for example, it is preferable to use RIE (Reactive Ion Etching) using Cl-based gas. In this way, for example, as shown in FIG. 6, the columnar mesa portion 20A is formed. At this time, the p-type diffusion region 11 is exposed at the skirt of the mesa portion 20A. Further, an oxidized layer 27D made of, for example, AlAs is exposed on the side surface of the mesa portion 20A. After that, the resist layer 120 is removed.

Next, in a water vapor atmosphere, an oxidation treatment is performed at a high temperature to selectively oxidize Al contained in the oxidized layer 27D from the side surface of the mesa portion 20A. Alternatively, Al contained in the oxidized layer 27D is selectively oxidized from the side surface of the mesa portion 20A by a wet oxidation method. As a result, in the mesa portion 20A, the outer edge region of the oxidized layer 27D becomes an insulating layer (aluminum oxide), and the current constriction layer 27 is formed (FIG. 7).

Next, after forming the electrode layer 32 in contact with the upper surface of the mesa portion 20A (for example, the n-type contact layer 26), the insulating layer 33 covering the mesa portion 20A is formed. At this time, an opening is formed at a predetermined position in the skirt of the mesa portion 20A. The p-type diffusion region 11 is exposed on the bottom surface of this opening. Next, an electrode layer 31 in contact with the surface of the p-type diffusion region 11 is formed in this opening. In this way, the surface emitting laser 1 is manufactured.

[motion]
In the surface emitting laser 1 having such a configuration, the electrode layer 31 electrically connected to the p-type DBR layer 21 via the p-type diffusion region 11 and the n-type DBR layer 25 via the n-type contact layer 26. When a predetermined voltage is applied between the electrically connected electrode layer 32 and the electrode layer 32, the current narrowed by the current narrowing layer 27 is injected into the active layer 23, whereby light emission due to recombination of electrons and holes is performed. Occurs. As a result, the vertical resonator in the mesa section 20A causes laser oscillation at _{an oscillation wavelength of λ 0.} Then, the light leaked from the p-type DBR layer 21 becomes a beam-shaped laser beam L and is output to the outside from the light emitting surface 1S.

[effect]
Next, the effect of the surface emitting laser 1 according to the present embodiment will be described.

In a surface emitting laser, a contact layer may be provided between the substrate and the substrate-side DBR as an energization path from the electrode to the substrate-side DBR. In this case, the contact layer is responsible for both reducing the contact resistance between the electrode and the substrate-side DBR and transporting the carrier from the electrode into the substrate-side DBR. Therefore, light absorption due to impurities in the contact layer occurs. Although it is possible to reduce light absorption by thinning the contact layer, in such a case, the resistance value of the contact layer rises, so that the drive voltage rises.

On the other hand, in the present embodiment, a p-type diffusion region 11 having a relatively high p-type impurity concentration is formed on the substrate 10 from at least the region facing the outer edge of the mesa portion 20A to the region of the skirt of the mesa portion 20A, and the electrode. The layer 31 is in contact with the p-type diffusion region 11. As a result, the p-type diffusion region 11 functions as an energization path from the electrode layer 31 to the mesa portion 20A (p-type DBR layer 21). At this time, by forming the p-type diffusion region 11 in a region of the surface on the mesa portion 20A side excluding at least the region facing the center of the mesa portion 20A, light absorption by impurities in the p-type diffusion region 11 is absorbed. It can be suppressed. Therefore, both high optical output and low drive voltage can be achieved at the same time.

In the present embodiment, the electrode layer 31 is in contact with the skirt region of the mesa portion 20A on the surface of the p-type diffusion region 11. As a result, the electrode layers 31 and 33 can be provided in the region opposite to the light emitting surface 1S in the positional relationship with the substrate 10, so that, for example, the surface emitting laser 1 and the surface emitting laser 1 are driven. By sticking the circuit boards including the circuit to each other, it is possible to make electrical contact between the surface emitting laser 1 and the circuit for driving the surface emitting laser 1.

In the present embodiment, when the substrate 10 is a semi-insulating semiconductor substrate or a low-doped p-type semiconductor substrate, the substrate 10 suppresses light absorption, and the substrate 10 causes the mesa portion 20A and the electrode layer 31. Can be supported.

<Second Embodiment>
[composition]
Next, the surface emitting laser array 2 according to the second embodiment of the present disclosure will be described. FIG. 8 shows an example of cross-sectional configuration of the surface emitting laser array 2. FIG. 9 shows an example of the upper surface configuration of the surface emitting laser array 2.

The surface emitting laser array 2 includes a plurality of surface emitting lasers 1 arranged two-dimensionally. The surface emitting laser array 2 includes a plurality of mesa portions 20A two-dimensionally arranged on the substrate 10, and further includes a pedestal portion 20B having a layer structure (epitaxial laminated structure 20) common to the mesa portion 20A. There is. The surface of the pedestal portion 20B is covered with the insulating layer 33, and the surface of the pedestal portion 20B is provided with a lead-out wiring 34 in contact with the electrode layer 31. In the surface emitting laser array 2, the laser light L generated by each mesa portion 20A is emitted from the back surface of the substrate 10.

In the present embodiment, the p-type diffusion region 11 of each surface emitting laser 1 is shared, and the electrode layer 31 of each surface emitting laser 1 is shared. As a result, it is possible to reduce the occurrence of voltage drop due to the electrode layer 31 and the p-type diffusion region 11 according to the distance from the pedestal portion 20B. For example, the p-type diffusion region 11 is formed on the surface of the substrate 10 on the mesa portion 20A side from a region facing the outer edge of each mesa portion 20A to a region of the entire skirt of each mesa portion 20A. Further, for example, the electrode layer 31 is in contact with the entire skirt of each mesa portion 20A and the pedestal portion 20B on the surface of the p-type diffusion region 11. The pedestal portion 20B functions as an electrode pad when energized.

Although the present disclosure has been described above with reference to the embodiments and examples thereof, the present disclosure is not limited to the above-described embodiments and the like, and various modifications are possible.

For example, in each of the above embodiments, the p-type diffusion region 11 is formed in a region of the surface on the mesa portion 20A side, excluding at least a region facing the center of the mesa portion 20A. However, for example, in each of the above embodiments, the p-type diffusion region 11 may be formed in at least a region of the surface on the mesa portion 20A side facing the center of the mesa portion 20A. However, in this case, in the p-type diffusion region 11, the p-type impurity concentration in the region facing the center of the mesa portion 20A is sufficiently lower than the p-type impurity concentration in the region facing the outer edge of the mesa portion 20A. As a result, light absorption due to impurities in the p-type diffusion region 11 can be reduced.

Further, for example, in each of the above embodiments, the case where the surface emitting laser 1 is formed of an arsenic semiconductor has been exemplified. However, in each of the above embodiments and modifications thereof, the surface emitting laser 1 is formed of a group III-V semiconductor containing, for example, nitrogen (N), boron (B), antimony (Sb), and phosphorus (P). May be.

Further, for example, in each of the above-described embodiments and modifications thereof, the surface emitting laser 1 is of the back surface emitting type, but it may be of the top surface emitting type. In this case, the electrode layer 32 has a ring shape having an opening at least in a region facing the current constriction region 27A, and even if the bottom surface of the opening provided in the electrode layer 32 is a light emitting surface. good.

The effects described in this specification are merely examples. The effects of the present disclosure are not limited to the effects described herein. The present disclosure may have effects other than those described herein.

Further, for example, the present disclosure may have the following structure.
(1)
With the board
A mesa portion formed by an epitaxial crystal growth method using the substrate as a crystal growth substrate, and containing a first conductive DBR (distributed Bragg reflector) layer, an active layer, a second conductive DBR layer, and a second conductive contact layer in this order. When,
The first electrode layer in contact with the substrate and
A second electrode layer in contact with the second conductive contact layer is provided.
The substrate has a first conductive diffusion region in which the concentration of impurities of the first conductive type is relatively high, at least from a region facing the outer edge of the mesa portion to a region at the base of the mesa portion.
The first electrode is a surface emitting laser in contact with the first conductive diffusion region.
(2)
The surface emitting laser according to (1), wherein the first conductive diffusion region is formed in a region of the surface on the mesa portion side, excluding at least a region facing the center of the mesa portion.
(3)
The surface emitting laser according to (1) or (2), wherein the first electrode layer is in contact with a region of the skirt of the mesa portion on the surface of the first conductive diffusion region.
(4)
The substrate is described in any one of (1) to (3), which is a semi-insulating semiconductor substrate or a low-doped semiconductor substrate having a first conductive type impurity concentration lower than that of the first conductive type diffusion region. Surface emitting laser.

In the surface emitting laser according to the embodiment of the present disclosure, at least from the region facing the outer edge of the mesa portion to the region of the skirt of the mesa portion, the first conductive type diffusion region having a relatively high concentration of the first conductive type impurities is formed. It is formed on a substrate and the first electrode is in contact with the first conductive diffusion region. As a result, the first conductive diffusion region functions as an energization path from the first electrode to the first conductive DBR layer. At this time, by forming the first conductive diffusion region in a region of the surface on the mesa portion side excluding at least the region facing the center of the mesa portion, light absorption by impurities in the first conductive diffusion region is achieved. It can be suppressed. Further, even when the first conductive diffusion region is formed in the region of the surface on the mesa portion side facing the center of the mesa portion, the first conductive diffusion region faces the center of the mesa portion. By making the impurity concentration in the region facing the outer edge of the mesa portion sufficiently lower than the impurity concentration in the region facing the outer edge of the mesa portion, it is possible to reduce the light absorption due to the impurities in the first conductive diffusion region. Therefore, both high optical output and low drive voltage can be achieved at the same time.

This application claims priority on the basis of Japanese Patent Application No. 2020-056047 filed at the Japan Patent Office on March 26, 2020, and the entire contents of this application are referred to in this application. Incorporate for application.

One of ordinary skill in the art can conceive of various modifications, combinations, sub-combinations, and changes, depending on design requirements and other factors, which are included in the appended claims and their equivalents. It is understood that it is something to be done.

Claims

With the board
A mesa portion formed by an epitaxial crystal growth method using the substrate as a crystal growth substrate, and containing a first conductive DBR (distributed Bragg reflector) layer, an active layer, a second conductive DBR layer, and a second conductive contact layer in this order. When,
The first electrode layer in contact with the substrate and
A second electrode layer in contact with the second conductive contact layer is provided.
The substrate has a first conductive diffusion region in which the concentration of impurities of the first conductive type is relatively high, at least from a region facing the outer edge of the mesa portion to a region at the base of the mesa portion.
The first electrode is a surface emitting laser in contact with the first conductive diffusion region.
The surface emitting laser according to claim 1, wherein the first conductive diffusion region is formed in a region of the surface on the mesa portion side, excluding at least a region facing the center of the mesa portion.
The surface emitting laser according to claim 2, wherein the first electrode layer is in contact with a region of the skirt of the mesa portion on the surface of the first conductive diffusion region.
The surface emitting laser according to claim 1, wherein the substrate is a semi-insulating semiconductor substrate or a low-doped semiconductor substrate having a first conductive type impurity concentration lower than that of the first conductive type diffusion region.