JP7453588B2 - Vertical cavity surface emitting laser device - Google Patents

Description

The present disclosure relates to a vertical cavity surface emitting laser device.

Research has been progressing on laser devices that function as vertical cavity surface emitting lasers using nitride semiconductors, and for example, a structure has been proposed in which current confinement is achieved by forming steps in a semiconductor stack. (See Patent Document 1, etc.).
As a current confinement structure for the p-type semiconductor layer of a surface-emitting laser element having a GaN-based semiconductor stack, for example, an insulating film having an opening is formed on the surface of the p-type semiconductor layer, and the p-type An example is a structure in which a transparent electrode such as ITO is formed on the surface of a semiconductor layer. The portion where the p-type semiconductor layer and the transparent electrode are in contact with each other in the opening of the insulating film is the current injection region of the surface emitting laser element. A light reflecting layer made of a dielectric multilayer film is provided on the surface of the transparent electrode opposite to the semiconductor layer, extending from the inside to the outside of the opening of the insulating film. That is, the dielectric multilayer film is provided in an area with a step difference.

Japanese Patent Application Publication No. 2015-035541

However, in such a surface emitting laser device, the concave part of the step is the current injection region, so the more layers of the dielectric multilayer film are stacked, the more the step region affected by the step becomes the center of the current injection region. Get closer. The reflectance of the dielectric multilayer film differs between flat areas and stepped areas. Therefore, such a surface emitting laser element has a problem in that it is difficult to control the shape of the oscillated laser light.
The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a vertical cavity surface emitting laser element that can stabilize the shape of oscillated laser light.

In the vertical cavity surface emitting laser device according to one aspect of the present disclosure, n
A nitride semiconductor stacked body in which a side semiconductor layer, an active layer, and a p-side semiconductor layer having a convex portion are stacked in this order;
a translucent p-electrode that contacts the upper surface of the protrusion and extends to the surrounding surface of the protrusion;
a second light-reflecting film extending from above to the side of the convex portion, disposed on the p-electrode, and including a dielectric laminated film;
An insulating film is provided that is spaced apart from the upper surface of the convex portion and covers at least a part of the surface of the p-side semiconductor layer around the convex portion.

According to the vertical cavity surface emitting laser device of the above embodiment, the shape of the oscillated laser light can be stabilized.

FIG. 1 is a schematic plan view of main parts for explaining the structure of a vertical cavity surface emitting laser device according to an embodiment of the present invention. 1A is a schematic cross-sectional view taken along line IB-IB in FIG. 1A. FIG. FIG. 1B is a schematic cross-sectional view of essential parts showing a laminated structure in the current confinement structure of the vertical cavity surface emitting laser device of FIG. 1A. 1A is a schematic cross-sectional view of a main part showing a modification of the vertical cavity surface emitting laser device of FIG. 1A. FIG. 1A is a schematic plan view for explaining a method of manufacturing the vertical cavity surface emitting laser device of FIG. 1A. FIG. FIG. 3B is a schematic cross-sectional view taken along line IIIB-IIIB in FIG. 3A. 1A is a schematic plan view for explaining a method of manufacturing the vertical cavity surface emitting laser device of FIG. 1A. FIG. FIG. 4B is a schematic cross-sectional view taken along line IVB-IVB in FIG. 4A. 1A is a schematic plan view for explaining a method of manufacturing the vertical cavity surface emitting laser device of FIG. 1A. FIG. 5A is a schematic cross-sectional view taken along the line VB-VB of FIG. 5A. FIG. 3 is a schematic vertical cross-sectional view for explaining a method of manufacturing the vertical cavity surface emitting laser device of FIG. 2. FIG. 3 is a schematic vertical cross-sectional view for explaining a method of manufacturing the vertical cavity surface emitting laser device of FIG. 2. FIG. 1A is a photograph showing a near-field image from above of the vertical cavity surface emitting laser device of FIG. 1A. FIG. 7 is a schematic cross-sectional view showing a main part of a vertical cavity surface emitting laser device according to a modified example.

Embodiments of the present disclosure will be described below with appropriate reference to the drawings. However, the embodiments described below are for embodying the technical idea of the present disclosure, and unless there is a specific description, the present disclosure is not limited to the following. Furthermore, the content described in one embodiment or example is also applicable to other embodiments or examples. The sizes, thicknesses, positional relationships, etc. of members shown in each drawing may be exaggerated for clarity of explanation.

A vertical cavity surface emitting laser device according to an embodiment of the present invention, as shown in FIGS. 1A and 1B,
It includes a first light-reflecting film 1 , a nitride semiconductor stack 5 , a transparent p-electrode 6 , a second light-reflecting film 8 , and an insulating film 7 . The stacked body 5 is disposed on the upper surface of the first light reflective film 1, and includes an n-side semiconductor layer 2, an active layer 3, and a p-side semiconductor layer 4 having a convex portion 4a, which are stacked in this order. The p-electrode 6 contacts the upper surface of the convex portion 4a and extends to the surface around the convex portion 4a. The second light reflective film 8 is
It extends from above to the side of the convex portion 4a, is placed on the p-electrode 6, and includes a dielectric laminated film. The insulating film 7 is spaced apart from the upper surface of the protrusion 4 a and covers at least a part of the surface of the p-side semiconductor layer 4 around the protrusion 4 a. That is, the insulating film 7 is not provided on the upper surface of the convex portion 4a.
By using a vertical cavity surface emitting laser device having such a configuration, the upper surface of the convex portion of the p-side semiconductor layer is used as a current injection region, and the portion of the second light reflection film 8 located directly above the current injection region can be made flat. Thereby, it is possible to reduce the loss of light due to scattering by the second light reflection film 8 directly above the current injection region. As a result, the shape of the laser beam oscillated from the vertical cavity surface laser element can be stabilized. Furthermore, it is possible to reduce the threshold current of the vertical cavity surface emitting laser element. Note that in this specification, the direction from the n-side semiconductor layer 2 to the p-side semiconductor layer 4 is referred to as upward. Even if the top and bottom are reversed in the figure, the direction from the n-side semiconductor layer 2 to the p-side semiconductor layer 4 will be described as being upward.

(Nitride semiconductor laminate)
The nitride semiconductor stack 5 includes, for example, an n-side semiconductor layer 2 made of a GaN-based semiconductor, a GaN
The active layer 3 made of a GaN-based semiconductor and the p-side semiconductor layer 4 made of a GaN-based semiconductor form the first light reflecting film 1.
They are stacked on top in this order. Examples of GaN-based semiconductors include AlGaN
, GaN, and InGaN.
The n-side semiconductor layer 2 is a single layer or a multilayer, and is an n-type semiconductor layer doped with an n-type impurity such as Si.
It has one or more mold layers. The active layer 3 includes, for example, a quantum well layer made of InGaN and a quantum well layer made of GaN.
This is a laminate in which barrier layers consisting of the following are alternately laminated. The number of laminated layers can be appropriately set depending on desired characteristics. The p-side semiconductor layer 4 can have a p-side optical guide layer and a p-side contact layer disposed thereon. The p-side contact layer is a layer doped with a p-type impurity, such as Mg. The p-side optical guide layer can be a layer doped with p-type impurities at a lower concentration than the p-side contact layer or an undoped layer. In this case, the p-side contact layer is the uppermost layer of the p-side semiconductor layer 4.

The thicknesses of the n-side semiconductor layer 2, the active layer 3, and the p-side semiconductor layer 4 can be set as appropriate. The total film thickness from the upper surface of the first light-reflecting film 1 to the lower surface of the second light-reflecting film 8, which will be described later, is an integral multiple of λ/2n, and is set so that a standing wave is generated therebetween. Then, they are arranged so that the strongest part of the standing wave is located in the active layer 3, and the weakest part of the standing wave is located in the transparent p-electrode 6, which will be described later.

The stacked body 5 of nitride semiconductor layers has a convex portion 4 a on the upper surface of the p-side semiconductor layer 4 . This convex portion 4
The upper surface of a serves as a current injection region. Directly below the current injection region becomes a light emitting section. Convex portion 4a
Examples of the planar shape include circular, elliptical, and polygonal shapes, but a circular shape is preferable in consideration of injecting a more uniform current into the nitride semiconductor stack 5. The size of the upper surface of the convex portion 4a is, for example, a diameter or a side length of 3 μm to 12 μm. The side surface of the convex portion 4a may be perpendicular to the upper surface of the convex portion 4a, or may be inclined. for example,
The convex portion 4a may have a frustum shape. The height of the convex portion 4a is, for example, from several tens of nanometers to several hundred nanometers.
m, and can range from 50 nm to 200 nm.
In this manner, by forming the convex portion 4a on the upper surface of the p-side semiconductor layer 4, a light emitting portion can be defined. Further, by forming the convex portion 4a, a difference in refractive index can be provided between the resonator portion and its peripheral portion, thereby making it possible to confine light in the lateral direction.

The convex portion 4a projects upward. The upper surface of the convex portion 4a is preferably formed of a p-side contact layer doped with the highest concentration of p-type impurities among the p-side semiconductor layers. The entire convex portion 4a may be formed only by the p-side contact layer, but it is preferable that the highly doped p-side contact layer be formed as a relatively thin film, while stably forming the convex portion 4a. For this purpose, it is preferable that the height of the convex portion 4a is high to some extent. For this reason, the convex portion 4
Preferably, a has a layer doped with a p-type impurity at a lower concentration than the p-side contact layer or an undoped layer. It is preferable that such a lightly doped or undoped layer is disposed on the surface of the p-side semiconductor layer 4 located around the convex portion 4a. In this case, the lightly doped or undoped layer is also arranged below the convex portion 4a. Such a lightly doped or undoped layer is, for example, a p-side light guide layer. In other words, the p-type impurity concentration of the layer constituting the upper surface of the convex portion 4a is preferably higher than the p-type impurity concentration of the layer constituting the surface around the convex portion 4a. This allows the upper surface of the convex portion 4a to make contact with the transparent p-electrode 6. Furthermore, even if the surface around the convex portion 4a is in contact with the p-electrode 6,
Current can be substantially not injected into that portion. Therefore, current can be efficiently injected substantially only from the upper surface of the convex portion 4a. The p-type impurity concentration of the layer constituting the surface around the convex portion 4a can be, for example, 1×10 ¹⁷ cm ⁻³ to 1×10 ¹⁹ cm ⁻³ , and the p-type impurity concentration of the layer constituting the upper surface of the convex portion 4 a The p-type impurity concentration is, for example, 1×10 ²⁰ cm ^-3
~5×10 ²⁰ cm ^-3 . The layer constituting the surface around the convex portion 4a is, for example, a p-side light guide layer. The layer forming the upper surface of the convex portion 4a is a p-side contact layer. In order to form a second light reflecting film 8, which will be described later, flat, the upper surface of the convex portion 4a is preferably a flat surface.

In the stacked body 5 of nitride semiconductor layers, the p-side semiconductor layer 4 and the active layer 3 are removed in the thickness direction on the outer peripheral portion of the above-mentioned convex portion 4a, that is, on the upper surface side of the convex portion 4a, and the n-side semiconductor layer is removed. 2 is preferably partially exposed. This allows the p-electrode and n-electrode to supply current to the laser element to
The electrodes can be placed on the same side of the stack.

A stacked body 5 of nitride semiconductor layers is arranged on the first light reflective film 1. The first light reflective film 1 is configured to include, for example, a semiconductor multilayer film and a dielectric multilayer film. A light reflecting film can be obtained by alternately stacking two or more films having different refractive indexes. As a semiconductor multilayer film,
A nitride semiconductor layer, for example, an AlGaInN compound semiconductor can be mentioned. Specifically, Ga
Examples include N, AlGaN, GaInN, and AlGaInN. Among these, a combination of GaN and AlInN, which is lattice matched to GaN, is preferred. Examples of dielectric laminated films include:
Examples include oxides, nitrides, and fluorides of Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, and Ti.
In the first light reflecting film 1, the material constituting each layer, the film thickness, the number of layers, etc. can be appropriately selected in order to obtain the intended reflectance. For example, the thickness of each layer constituting the laminated film is λ/4n (where λ is the oscillation wavelength of the laser, and n is the refractive index of the medium constituting each layer), and the oscillation wavelength λ
, can be appropriately set depending on the refractive index n of the material used at the oscillation wavelength λ. Specifically, it is preferable to set it to an odd multiple of λ/4n. For example, in a light emitting device with an oscillation wavelength λ of 410 nm, when the first light reflecting film is made of GaN/AlInN, the thickness of each layer is 40 nm.
Examples include nm to 70 nm. The number of laminated films can be appropriately set depending on the intended characteristics. The number of laminated layers in the laminated film may be two or more layers, for example, 5 to 100 layers. The total thickness of the first light reflecting film 1 can be, for example, 0.08 μm to 7 μm.
The size and shape of the first light reflecting film 1 can be designed as appropriate as long as it covers the light emitting part of the laser element.

The first light reflective film 1 and the nitride semiconductor layer stack 5 can be formed, for example, on the substrate 11 for semiconductor growth, and can be formed by a method known in the art. Convex portion 4
The formation of a and the partial exposure of the n-side semiconductor layer 2 may be performed using methods such as photolithography and etching after forming the stacked body 5 of nitride semiconductor layers.

(p electrode 6)
The p-electrode 6 is an electrode for injecting current from the convex portion 4a of the p-side semiconductor layer 4, and is an electrode that is in contact with at least the upper surface of the convex portion 4a. The p-electrode 6 may extend to the side surface of the convex portion 4a, or may extend to the upper surface of the p-side semiconductor layer 4 around the convex portion 4a. For example, the p-electrode 6 is disposed from the top surface of the convex portion 4a, passing through the side surface of the convex portion 4a, and extending onto the p-side semiconductor layer 4 around the convex portion 4a. As described above, when the upper surface of the convex portion 4a is formed of the p-side contact layer doped with p-type impurities at a high concentration, at least the convex portion 4a
Current can be injected from the p-electrode 6 on the top surface of the . Further, as described above, the convex portion 4a
When the surface of the p-side semiconductor layer 4 located around the p-side semiconductor layer 4 is formed of a layer lightly doped with p-type impurities, the p-electrode 6 forms a Schottky contact at this portion. Therefore, current is injected only from the p-side contact layer, and current confinement is possible without providing an insulating film between the p-electrode 6 and the p-side semiconductor layer 4.

The size of the planar area of the p-electrode 6 is not particularly limited as long as it is in contact only with the p-side semiconductor layer 4; The size may be such that the outer edge is located inside the outer edge of the outer edge.
The p-electrode 6 is a conductive member made of a material that is transparent to the wavelength range of laser oscillation. Translucent materials include indium-tin oxide (ITO, Sn-doped In ₂ O ₃ , including crystalline and amorphous), indium-zinc oxide (IZO), IFO (F-doped In ₂ O ₃ ), tin oxide (SnO ₂ ), ATO (Sb-doped SnO ₂ ), FTO (F-doped SnO ₂ ), zinc oxide (including ZnO, Al-doped ZnO, and B-doped ZnO), gallium oxide, titanium Examples include transparent conductive materials having base materials such as oxide, niobium oxide, and nickel oxide. A specific example is ITO. The thinner the film thickness is, the more light absorption by the p-electrode 6 can be reduced, while the resistance increases, so it can be adjusted as appropriate by considering the balance between these. The thickness of the p-electrode 6 is, for example, 5 nm to 100 nm.

(Second light reflective film 8)
The second light reflecting film 8 is disposed on the p-electrode 6, and is disposed from the upper surface of the convex portion 4a to at least a portion of the surface around the convex portion 4a. With this arrangement, the second light reflecting film 8 can be formed flat directly above the current injection region. At least a part of the surface around the protrusion 4a is, for example, a region surrounding the protrusion 4a, which is approximately 10% to 50% larger than the diameter or side length of the protrusion 4a. An example is the area of sa. Although it is preferable that the area of the upper surface of the convex portion 4a be small in order to perform current confinement, it is easier to form the second light reflecting film 8 if the planar area is large to some extent. For this reason, it is preferable that the second light reflection film 8 is provided not only on the upper surface of the convex portion 4a but also in a region including at least a part of the surface around the convex portion 4a.
The second light reflecting film can be configured to include a dielectric multilayer film. The second light-reflecting film can have the same structure as the dielectric multilayer film exemplified in the first light-reflecting film 1 described above. for example,
_Examples include _SiO2 / _Nb2O5 , _SiO2 / _Ta2O5 , _{and SiO2 / Al2O3} . The thickness of each layer is λ/4n (here, λ is the oscillation wavelength of the laser, and n is the refractive index of the medium constituting each layer)
It is. The number of laminated layers can be appropriately set depending on the intended characteristics. Specifically, when the second light reflecting film 8 is made of SiO ₂ /Nb ₂ O ₃ or the like, each layer has a thickness of 40 nm to 70 nm. The number of layers in the laminated film may be two or more layers, for example, 5 to 20 layers. The overall thickness of the second light reflecting film 8 is, for example, 0.08 μm to 2.0 μm, and 0.08 μm to 2.0 μm, for example.
．． It can be 6 μm to 1.7 μm.
It is preferable that the second light reflecting film 8 is placed apart from the insulating film 7, which will be described later.

(Insulating film 7)
The insulating film 7 is arranged apart from the upper surface of the convex portion 4a. The insulating film 7 covers at least a part of the surface around the protrusion 4 a of the p-side semiconductor layer 4 . The formation position and thickness of the insulating film 7 are set so that the second light reflecting film 8 is flat directly above the upper surface of the convex portion 4a. The insulating film 7 is the second
It is preferable that the light reflecting film 8 be spaced apart from the light reflecting film 8 . Thereby, the second light reflecting film 8 can be more reliably arranged flatly just above the upper surface of the convex portion 4a. Further, as shown in FIG. 8, the thickness of the insulating film 7 is set to such an extent that it does not reach the upper surface of the convex part 4a, and the insulating film 7 is in contact with the side surface of the convex part 4a, but only on a part of the side surface of the convex part 4a, for example. It may be arranged so as to cover less than half of the area. With such an arrangement, the second light reflecting film 8 can be made flat just above the upper surface of the convex part 4a, and the insulating film 7 can more reliably protect the p-side semiconductor layer 4 around the convex part 4a. It is possible to prevent current injection into. Further, the insulating film 7 may cover not only the p-side semiconductor layer 4 but also the side surface of the active layer 3 and a part of the exposed upper surface of the n-side semiconductor layer 2, and may further cover the stacked body 5.
The sides may be covered.
The insulating _{film 7} is made _{of a} SiO _{x type} material including SiO _{2 ,} a _{SiN Y} type material such as SiN, _{a SiO} It can be formed from an inorganic material or the like. It is preferable that the material constituting the insulating film has a lower refractive index than the material constituting the laminate 5.

(Other parts)
(Pad electrode 9p, n electrode 9n)
The vertical cavity surface emitting laser device 10A further includes a p pad electrode 9p electrically connected to a transparent p electrode 6 formed on the p side semiconductor layer 4, and an exposed n side semiconductor layer 2. It is preferable that an n-electrode 9n electrically connected to the n-electrode 9n be disposed.
These p-pad electrode 9p and n-electrode 9n may be formed of any conductive material commonly used as electrodes in the field. For example, Ti/Pt/Au, Ti/Rh/
Examples include Au. The pad electrode 9p is preferably arranged in a shape surrounding the outer periphery of the convex portion 4a. Thereby, current can be more uniformly injected into the p-side semiconductor layer 4 from the pad electrode 9p via the p-electrode 6. Moreover, it is preferable that the pad electrode 9p be arranged apart from the second light reflection film 8. In this way, by not disposing the p pad electrode 9p directly under the second light reflective film 8, the flatness of the second light reflective film 8 directly above the current injection region can be more reliably ensured.
The n-electrode 9n and the pad electrode 9p may be formed of the same or different materials and have a single layer structure, may be formed of the same material and have the same laminated structure, or may be formed of different materials and have different laminated structures. may be formed. When the n-electrode 9n and the pad electrode 9p are formed of the same material and have the same laminated structure, the n-electrode 9n and the pad electrode 9p can be formed in the same process.

(Substrate 11)
Since the nitride semiconductor stack 5 is usually stacked on a substrate for semiconductor growth, the vertical cavity surface emitting laser device may have a substrate 11 for semiconductor growth. When the first light reflective film 1 is formed from a nitride semiconductor, the first light reflective film 1 is first formed on the substrate 11,
A laminate 5 is formed thereon. Further, after forming the laminate 5, the semiconductor growth substrate may be removed from the laminate 5, and the first light reflective film 1 may be formed on the surface of the laminate 5 exposed by the removal. Examples of the substrate 11 for semiconductor growth include substrates made of nitride semiconductors (such as GaN), sapphire, silicon carbide, and silicon.

(Heat dissipation board 12)
The above-described vertical cavity surface emitting laser element may be bonded to a heat dissipation substrate 12, as shown in FIG. Examples of the heat dissipation substrate 12 include a semiconductor substrate made of ceramics such as AlN, a semiconductor such as silicon carbide, a single metal substrate, a metal substrate made of a composite of two or more metals, and the like. For example, an insulating AlN ceramic is used as the base material, and a plurality of metal films 15 are formed on the surface of the base material.
A substrate on which is formed can be used as the heat dissipation substrate 12. The metal film 15 is
It is electrically connected to the p pad electrode 9p and the n electrode 9n. In cases where a p-electrode and an n-electrode are arranged with the laminate 5 in between, or when the first light reflective film 1 side is bonded to the heat dissipation substrate 12, the p-electrode
When it is not necessary to electrically connect both the electrode and the n-electrode to the heat dissipation board 12, the heat dissipation board 12
A conductive substrate such as a metal substrate may be used as the substrate. The film thickness of the heat dissipation substrate 12 is, for example, 5.
Examples include about 0 μm to 500 μm.
As a method for forming the heat dissipation substrate 12, a method commonly used in the field can be used.

(Anti-reflection film 14)
The above-described vertical cavity surface-emitting laser element emits laser light from the first light-reflecting film 1 side, and has the above-described substrate 11 on the surface of the first light-reflecting film 1 opposite to the laminate 5. In some cases, an antireflection film 14 may be disposed on the surface of the substrate 11 opposite to the laminate 5. As the antireflection film 14, the same material as the dielectric multilayer film exemplified for the first light reflection film 1 described above can be used. By making the number of laminated layers and the thickness of each layer different from that of the light reflecting film, a film having an antireflection function can be formed. For example, SiO ₂ /Nb ₂ O ₅ , SiO ₂ /Ta ₂ O ₅ , S
Examples include iO ₂ /Al ₂ O ₃ . The thickness is, for example, 0.4 μm.

[Method for manufacturing vertical cavity surface emitting laser device]
The vertical cavity surface emitting laser device described above can be manufactured, for example, by the following method.
First, as shown in FIGS. 3A and 3B, a substrate 11 for semiconductor growth is prepared, a first light reflecting film 1 is formed, and an n-side semiconductor layer 2 is formed on the upper surface of the first light reflecting film 1. Active layer 3 and convex portion 4
A nitride semiconductor stack 5 is formed by stacking p-side semiconductor layers 4 having a nitride semiconductor layer 4 in this order. After forming the stacked body 5 of nitride semiconductor layers, the surface of the n-side semiconductor layer 2 is exposed by removing part of the p-side semiconductor layer 4 and the active layer 3 before and after forming the convex portion 4a. be able to.
Thereafter, as shown in FIGS. 3A and 3B, a transparent p-electrode 6 is formed that contacts the upper surface of the convex portion 4a and extends to the surface around the convex portion 4a.
Subsequently, as shown in FIGS. 4A and 4B, an insulating film 7 is formed to cover the sides of the protrusion 4a of the p-side semiconductor layer 4. Although the insulating film 7 may be formed so as not to contact the p-electrode 6, it is preferable to form the insulating film 7 so as to cover the outer periphery of the p-electrode 6, with a portion of the insulating film 7 covering the p-electrode 6.
Optionally, as shown in FIGS. 5A and 5B, after forming the insulating film 7, a p pad electrode 9p and an n electrode 9n are formed. In particular, by forming the p pad electrode 9p in a ring shape that is larger than the convex portion 4a and surrounds the upper surface of the convex portion 4a and its surroundings, the p pad electrode 9p
Current can be more uniformly injected into the p-side semiconductor layer 4 through the p-electrode 6 .
Next, as shown in FIGS. 1A and 1B, a second light reflecting film 8 including a dielectric laminated film is formed.
The second light reflecting film 8 is formed on the p-electrode 6, from the upper surface of the convex portion 4a to at least a portion of the surface around the convex portion 4a. It is preferable that the second light reflecting film 8 is placed apart from the insulating film 7 and not in contact with it. By forming the second light reflecting film 8 in this way, FIG.
As shown in C, on the upper surface of the convex portion 4a, that is, directly above the current injection region X, the second light reflection film 8 can be more reliably arranged flat to the end of the region X. This results in
Carriers can be effectively injected into the light emitting part. As a result, laser light can be obtained in the light emitting section. Note that the second light reflecting film 8 only needs to be flatly arranged up to the end of the current injection region X, and may be in contact with the insulating film 7 as long as it is flat.

When the vertical cavity surface emitting laser device thus obtained is bonded to a heat dissipating substrate, for example, as shown in FIG. to form a thinned substrate 11a. At this time, the substrate for semiconductor growth may be completely removed. Thinning or removal can be performed using polishing methods, etching methods, etc. known in the art.
Further, as shown in FIG. 6B, an antireflection film 1 is provided on the surface of the substrate 11a opposite to the first light reflection film 1.
4 may be formed. When completely removing the substrate 11, the antireflection film 14 is the first light reflection film 1.
may be formed on the surface of
Furthermore, as shown in FIG. 2, the obtained laminate 5 is bonded to a heat dissipation substrate 12. For the bonding layer 13 used for bonding, for example, in addition to the same material as the above-mentioned p pad electrode 9p and n electrode 9n, solder or the like can be used. The bonding layer 13 can be arranged so as to be bonded to the p-pad electrode 9p and the n-electrode 9n, respectively, and to the metal film 15 of the heat dissipation substrate 12, respectively. In this case, the bonding layer 13 is conductive, and the p pad electrode 9p is connected via the bonding layer 13.
and one metal film 15 are electrically connected, and the n-electrode 9n and another metal film 15 are electrically connected. Further, the area between the heat dissipation substrate 12 and the obtained laminate 5, that is, the area other than the area where the bonding layer 13 in the laminate 5 is arranged, may remain hollow, or may be made of an insulating heat dissipation member, etc. You can also embed it by
For example, after arranging the bonding layer 13 as shown in FIG. 2, the bonding layer 13 is bonded by heating.
This can be done by softening.
Note that the bonding of the laminate 5 to the heat dissipation substrate 12 may be performed before thinning the substrate 11 and/or forming the antireflection film 14.

Test example 1
As shown in FIGS. 1A and 1B, the vertical cavity surface emitting laser device 10A includes a GaN substrate 11, a nitride semiconductor stack 5, a transparent p-electrode 6 (30 nm thick) made of ITO, and a dielectric Second light reflecting film 8 including laminated film (SiO ₂ /Nb ₂ O ₃ , λ/4 thickness, 15.5 pairs)
Then, a laser element having an insulating film 7 (SiO ₂ , 100 nm thick) was formed. The laminate 5 is
First light reflective film 1 (GaN/Al _0.8 In _0.2 N = 46.6 nm/51.2 nm thick), n-side semiconductor layer 2 (Si-doped GaN), active layer 3 (GaN/InGaN), p-side semiconductor layer 4 (M
g-doped GaN and undoped AlGaN) are stacked in this order. p-side semiconductor layer 4
has a convex portion 4a (height: 70 nm, diameter: 5 μm, top view shape: circular). The p-electrode 6 contacts the upper surface of the convex portion 4a and extends to the surface around the convex portion 4a. The second light reflecting film 8 extends to the side of the convex portion 4a and is disposed on the p-electrode 6. The insulating film 7 is spaced apart from the second light reflecting film 8 and covers at least a portion of the surface around the protrusion 4 a of the p-side semiconductor layer 4 . In a part of the stacked body 5, the p-side semiconductor layer 4 and the active layer 3 are removed to expose the n-side semiconductor layer 2, and an n-electrode 9n and a p-pad electrode 9p are formed on the surface and the p-electrode 6. (Ti/Pt/A
u, 1.5 nm/200 nm/500 nm) were formed.

When the vertical cavity surface emitting laser device 10A having such a configuration was operated continuously at room temperature by injecting a current (1 mA), laser light was emitted upward in FIG. 1B. When the near-field image (NFP) of the vertical cavity surface emitting laser device 10A was observed from above, it was confirmed that oscillation occurred in the center of the current injection region (dotted line), as shown in FIG. In FIG. 7, the shape of the NFP of the laser beam is approximately circular, and it can be said that the emission intensity at the center thereof is maximum. Note that FIG. 7 shows that the closer the color is to white, the higher the emission intensity is.
In this way, the vertical cavity surface emitting laser device 10A of this embodiment can stabilize the shape of the oscillated laser beam.

1 First light-reflecting film 2 N-side semiconductor layer 3 Active layer 4 P-side semiconductor layer 4a Convex portion 5 Nitride semiconductor stack 6 P-electrode 7 Insulating film 8 Second light-reflecting film 9p, 9n Pad electrode 10A Vertical resonator Surface emitting laser element 11 Substrate for semiconductor growth 12 Heat dissipation substrate 13 Bonding layer 14 Antireflection film 15 Metal film

Claims (9)

a first light reflective film;
a nitride semiconductor stack in which an n-side semiconductor layer, an active layer, and a p-side semiconductor layer having a current injection region are stacked in this order on the upper surface of the first light-reflecting film;
a translucent p-electrode that contacts the upper surface of the current injection region and extends to the surrounding surface of the current injection region;
a second light reflecting film including a dielectric laminated film, which is disposed on the p-electrode and is disposed from the upper surface of the current injection region to at least a portion of the surface around the current injection region;
an insulating film that is spaced apart from the top surface of the current injection region and covers at least a portion of the side surface of the stacked body;
Equipped with
A vertical cavity surface emitting laser device in which a portion of the insulating film is disposed on the p-electrode . a first light reflective film;
a nitride semiconductor stack in which an n-side semiconductor layer, an active layer, and a p-side semiconductor layer having a current injection region are stacked in this order on the upper surface of the first light-reflecting film;
a translucent p-electrode that contacts the upper surface of the current injection region and extends to the surrounding surface of the current injection region;
a second light reflecting film including a dielectric laminated film, which is disposed on the p-electrode and is disposed from the upper surface of the current injection region to at least a portion of the surface around the current injection region;
an insulating film that is spaced apart from the top surface of the current injection region and covers at least a portion of the side surface of the stacked body;
Equipped with
The p-side semiconductor layer has a p-side optical guide layer and a p-side contact layer disposed on the p-side optical guide layer,
The current injection region has the p-side contact layer on its upper surface, and the surface around the current injection region is the surface of the p-side optical guide layer. 3. The vertical cavity surface emitting laser device according to claim 1 , wherein the insulating film covers a part of the surface of the p-side semiconductor layer around the current injection region. 4. The vertical cavity surface emitting laser device according to claim 3 , wherein the insulating film is spaced apart from the second light reflecting film. 5. The vertical cavity surface emitting laser device according to claim 1, further comprising a p pad electrode connected to the p electrode on a side of the current injection region and disposed on the insulating film. 6. The vertical cavity surface emitting laser device according to claim 5 , wherein the p pad electrode is spaced apart from the second light reflecting film. The vertical cavity surface emitting laser device according to claim 1 , wherein the first light reflecting film includes a semiconductor multilayer film. The vertical cavity surface emitting laser device according to claim 1, further comprising a heat dissipation substrate above the second light reflection film. 9. A portion of the n-side semiconductor layer is exposed on the upper surface side of the p-side semiconductor layer, and an n-electrode is connected to the n-side semiconductor layer. Vertical cavity surface emitting laser device.