JP3805295B2 - Nitride semiconductor laser - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a nitride semiconductor laser.
[0002]
[Prior art]
In recent years, GaN, InGaN, GaAlN, InGaAlN and other gallium nitride compound semiconductors (In _x Ga _y Al _z N, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) are in the ultraviolet region. Has been attracting attention as a material for short-wavelength semiconductor lasers ranging from the visible light to the green region. In nitride semiconductor lasers using this gallium nitride compound semiconductor, for example, Nichia Nakamura et al., Appl. Phys. Lett. 72 (2). 211 (1998), a ridge waveguide laser is desirable. In a ridge waveguide laser using a nitride semiconductor, the active layer width for horizontal transverse mode control can be as wide as about 2 μm, and the lithography is easy, so that the yield can be increased. For this reason, it is expected as a pickup light source for an optical disk recording / reproducing apparatus.
[0003]
FIG. 2 is a diagram showing a conventional ridge structure nitride semiconductor laser. On the sapphire substrate 200, a buffer layer 210, an SiO ₂ mask 211, an n-type contact layer 212 made of GaN, an n-type superlattice cladding layer 213 made of AlGaN / GaN, an n-side guide layer 214 made of GaN, and InGaN are included. An active layer 215 having a quantum well structure, a p-side guide layer 216 made of GaN, and a p-type superlattice cladding layer 217 made of AlGaN / GaN are sequentially formed. The p-type superlattice clad layer 217 includes a first p-type clad layer 217A and a second p-type clad layer 217B formed in a ridge shape by etching on a part of the first p-type clad layer 217A. And consist of A p-type contact layer 218 made of GaN is formed on the second p-type cladding layer 217B. The upper surface portion excluding the p-type contact layer 218 and a part of the side surface are covered with an insulating film 219. On the p-type contact layer 218, a p-side electrode 221 that is an electrode on one side is formed. The n-side electrode 220 which is the other side electrode is formed on the n-type contact layer 212 exposed by etching.
[0004]
Current is injected into the active layer 215 from the p-side electrode 221 and the n-side electrode 220. Here, the width of the active layer 215 from the left side surface to the right side surface in the drawing is about 200 μm. In contrast, the width of the p-type contact layer 218 is as narrow as about 2 μm. For this reason, the current from the p-side electrode 221 is injected near the center of the active layer 215. As a result, light is emitted from the vicinity of the center of the active layer 215, the light is amplified, and laser light is output from the end face direction perpendicular to the paper surface.
[0005]
[Non-Patent Document 1]
Shuji Nakamura, et al., “Applied Physics Letters”, American Institute of Physics, January 12, 1998, Vol. 72, No. 2, p. 211-213
[0006]
[Problems to be solved by the invention]
The nitride semiconductor laser having the ridge structure described above has a higher threshold current and poor noise characteristics than other material lasers. That is, in the ridge waveguide laser, the current from the p-side electrode 221 tends to spread laterally from directly below the p-type contact layer 218, and the current is injected with high density and high efficiency near the center of the quantum well active layer 215. It is difficult. For this reason, the threshold current tends to increase. In addition, since the nitride semiconductor laser cannot increase the refractive index difference between the waveguide layers 214, 215, and 216 and the cladding layers 213 and 217 as compared with other group III-V compound semiconductor material-based lasers, optical confinement is possible. Is weak. For this reason, light is likely to be transmitted through the waveguide surface composed of the active layer 215 and the guide layers 214 and 216 in the direction perpendicular to the laser emission direction, that is, in the lateral direction in the figure. As a result, spontaneously emitted light leaks from the lateral direction in the figure to the outside of the chip, and noise characteristics tend to deteriorate.
[0007]
In order to solve this problem, it is conceivable to use a method in which the width from the n-type cladding layer 213 including the active layer 215 to the p-type cladding layer 217 is reduced to about several tens of μm. It is not a countermeasure. That is, if the width from the n-type clad layer 213 to the p-type clad layer 217 is reduced to about several tens of μm, it becomes possible to inject a current with high density and high efficiency near the center of the active layer. The current can be lowered. However, if the width from the n-type cladding layer 213 to the p-type cladding layer 217 is narrowed, the thermal resistance increases and the threshold current increases. In addition, light leakage in the lateral direction also increases. Furthermore, if the width from the n-type cladding layer 213 to the p-type cladding layer 217 is reduced, it becomes difficult to form wiring from the p-side electrode 221 to the outside using a wire.
[0008]
As described above, in the conventional nitride semiconductor laser, it is difficult to obtain a structure that efficiently injects high current density carriers necessary for the fundamental transverse mode gain into the active layer 215 while suppressing leakage of spontaneous emission light. is there. For this reason, in a conventional nitride semiconductor laser, spontaneous emission light that does not contribute to oscillation even during laser driving is emitted from other than the resonator and noise appears.
[0009]
As described above, in order to realize a highly reliable nitride semiconductor laser that operates at a low threshold current and a low voltage and continuously oscillates in the fundamental transverse mode, which is practically applied to an optical disk or the like, the carrier to the active layer Although it is important to form a structure that efficiently performs injection and cuts out leaked light, a configuration that satisfies these conditions has not yet been obtained.
[0010]
The present invention has been made in consideration of the above circumstances, and the object of the present invention is not only to easily form a basic transverse mode control structure, but also to reduce leakage light and to inject carriers at high density into the active layer. An object of the present invention is to provide a nitride semiconductor laser having a low threshold current and a low noise characteristic by a current confinement structure that can be performed.
[0011]
[Means for Solving the Problems]
The nitride semiconductor laser according to the present invention includes a first conductive semiconductor layer made of a gallium nitride compound semiconductor, an active layer formed on the first conductive semiconductor layer and made of a gallium nitride compound semiconductor, and the active layer. A first second conductive semiconductor layer made of a gallium nitride compound semiconductor and a mesa structure made of a gallium nitride compound semiconductor provided in a part on the first second conductive semiconductor layer. A second conductive semiconductor layer in the form of a mesa, and on both sides of the second second conductive semiconductor layer having the mesa structure, at least the second conductive semiconductor layer in parallel with the second second conductive semiconductor layer. A pair of grooves are formed so as to penetrate one second conductive type semiconductor layer and the active layer.
[0012]
The nitride semiconductor laser of the present invention includes a substrate, a first conductivity type semiconductor contact layer made of GaN formed on the substrate, and a first conductivity type semiconductor contact layer formed on the first conductivity type semiconductor contact layer. A conductive semiconductor clad layer; an active layer having a multiple quantum well structure formed on the first conductive semiconductor clad layer, containing InGaN, and emitting light of wavelength λ by current injection; and formed on the active layer , A first second-conductivity-type semiconductor clad layer containing AlGaN, and a stripe-shaped mesa structure having a bottom width W1 formed on a part of the first second-conductivity-type semiconductor clad layer. A second conductivity type semiconductor clad layer, and a second conductivity type semiconductor contact layer made of GaN formed on the second stripe conductivity type second clad layer, A first electrode formed in electrical connection with the first conductive type semiconductor contact layer, and a second electrode formed in electrical connection with the second conductive type semiconductor contact layer, The first second conductivity type is disposed on both sides of the second second conductivity type semiconductor clad layer in the form of stripes at a position parallel to the second second conductivity type semiconductor clad layer and separated by W2 (W1 ≦ W2) or more. A groove having a width of λ / 2 (λ is a light emission wavelength from the active layer) and 2 μm or less is formed so as to pass through the semiconductor clad layer and the active layer and reach the middle of the first conductivity type semiconductor clad layer. The first second-conductivity-type semiconductor clad layer, the second second-conductivity-type semiconductor clad layer, and a material having a refractive index lower than that of the first-conductivity-type semiconductor clad layer, and ZrO ₂ , SiO ₂ , TiO ₂ , AlGaN, The groove is filled with a material including at least one.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG. One of the features of this embodiment is that a groove 130 is formed in a nitride semiconductor laser having a ridge structure, as shown in FIG. Thereby, a nitride semiconductor laser having a low threshold current and a low noise characteristic can be provided.
[0014]
FIG. 1 is a cross-sectional view of a nitride semiconductor laser according to an embodiment of the present invention. On the sapphire substrate 100 having a thickness of 150 μm, an n-type (first conductivity type) contact layer having a thickness of 6 μm made of GaN doped with a buffer layer 110, a SiO ₂ mask 111, and 5 × 10 ¹⁸ cm ⁻³ of Si. 112, an n-type superlattice cladding layer 113 having a thickness of 1.5 μm made of undoped Al _0.10 Ga _0.90 N and Si-doped GaN, an n-side guide layer 114 having a thickness of 0.1 μm made of undoped GaN, Three quantum well layers of 3 nm thickness made of undoped In _0.15 Ga _0.85 N, and a barrier layer of 6 nm thickness made of undoped In _0.02 Ga _0.98 N across the quantum well layer An active layer 115 having a multiple quantum well structure, a p-side guide layer 116 made of Mg-doped GaN and having a thickness of 0.1 μm, and an undoped Al _0.10 Ga _0.9. A p-type (second conductivity type) superlattice clad layer 117 made of ₀ N and Mg-doped GaN and having a thickness of 0.8 μm is sequentially formed. The p-type superlattice clad layer 117 includes a first p-type clad layer (first second conductivity type semiconductor layer) 117A and a striped mesa type partly on the first p-type clad layer 117A. And a second p-type cladding layer (second second-conductivity-type semiconductor layer) 117B formed in the structure. The bottom width W1 of the second p-type cladding layer 117B is about 2 μm. On the second p-type cladding layer 117B, a 1-μm-thick p-type contact layer 118 made of GaN doped with 1 × 10 ¹⁸ cm ⁻³ Mg is formed. The upper surface portion excluding the p-type contact layer 118 and a part of the side surface are covered with an insulating film 119 in which ZrO ₂ / SiO ₂ is laminated in multiple layers. A p-side electrode (second electrode) 121 made of Pt / Au is formed on the p-type contact layer 118. The n-side electrode (first electrode) 120 which is the other electrode is made of Ti / Al / Ni / Au and is formed on the n-type contact layer 112 exposed by etching. The lateral width of the active layer 115 remaining after this etching is 200 μm. Although not particularly shown, a high reflection coat in which ZrO ₂ / SiO ₂ is laminated in multiple layers is also applied to the laser light emitting end face. 1, the thickness of the substrate 100 is 150 μm, the thickness of the stacked bodies 111 to 118 is about 10 μm, the width of the active layer 215 is 200 μm, and the bottom width W1 of the second p-type cladding layer 117B is 2 μm. However, for ease of explanation, the scale is changed.
[0015]
In the nitride semiconductor laser of FIG. 1, a current confinement structure 117B formed on the active layer 114 and for injecting carriers into the active layer 113 is formed in a mesa shape. For this reason, the current is injected near the center of the active layer 114 in the figure. Then, light is emitted from the active layer 114 by this current injection, the light is amplified, and laser light is emitted in a direction perpendicular to the paper surface.
[0016]
One of the features of the nitride semiconductor laser of FIG. 1 is that the strip-shaped (striped) second p-type cladding layer 117B is sandwiched on both sides thereof in parallel with the second p-type cladding layer 117B. The groove 130 formed so as to penetrate the p-type cladding layer 117A and the active layer 114 is formed. A distance W2 from the groove 130 to the mesa-type second p-type cladding layer (mesa-type current confinement structure) 117B is 5 μm, and the width of the groove 130 is 1 μm. As shown in FIG. 1, the groove 130 is embedded with an insulating film (embedding material) 119 made of ZrO ₂ / SiO ₂ having a refractive index lower than the effective refractive index of the laser. Here, the depth of the groove 130 is preferably up to the middle of the n-type superlattice cladding layer 113. When the n-type superlattice cladding layer 113 penetrates the n-type contact layer 112 and reaches the n-type contact layer 112, the n-type contact layer 112 is a material transparent to the light from the active layer 115. Light oozes out and high-order mode oscillation is likely to occur. The side surface shape of the groove 130 is preferably not vertical. Further, the relationship between the distance W2 (5 μm) from the inside of the groove 130 to the outside of the second p-type cladding layer 117B and the bottom width W1 (2 μm) of the second p-type cladding layer 117B is W1 ≦ W2 It is preferable that That is, the distance W2 (5 μm) between the inside of the groove 130 and the outside of the mesa current confinement structure 117B is at least separated from the width W1 (2 μm) of the mesa current confinement structure 117B, preferably as far as possible. The horizontal / horizontal mode becomes a stable basic mode, and the horizontal far-field image has a single peak shape without noise.
[0017]
Next, a method for manufacturing the nitride semiconductor laser will be described.
[0018]
(1) First, the buffer layer 110 is formed on the sapphire substrate 100 by metal organic chemical vapor deposition (MOCVD), and then a SiO ₂ film is deposited by thermal CVD or the like. This SiO ₂ film is patterned so as to have a line and space with an opening width of 4 μm and a SiO ₂ width of 10 μm in a direction parallel to a laser resonator to be formed later, thereby forming an SiO ₂ mask 111.
[0019]
(2) Next, by using the MOCVD method again, the stacked bodies 112 to 118 from the n-type contact layer 112 to the p-type contact layer 118 are grown.
[0020]
(3) Next, an etching mask is formed so as to be perpendicular to the SiO ₂ mask 111 and have a resonator length (length in a direction perpendicular to the paper surface) of 500 μm, and vertically etched to the sapphire substrate 100 by a dry etching method. A laser emission end face is formed.
[0021]
(4) Next, on the p-type contact layer 118, a stripe-shaped etching mask width 2 [mu] m, is formed at a position and the SiO ₂ mask 111 center the upper SiO ₂ mask 111 is not applied, the p-type by a dry etching method The superlattice clad layer 117 is etched halfway to form a mesa structure 117B.
[0022]
(5) Next, a groove 130 having a width of 1 μm that penetrates from the p-side guide layer 116 to the n-side guide layer 114 is formed at the position of the outer side W2 (5 μm) of the mesa structure 117B in order to cut the leaked light.
[0023]
(6) Next, in order to form the n-side electrode 120, a partial region of the crystal grown semiconductor layer is etched to the n-type contact layer 112. Next, an insulating film 119 in which ZrO ₂ / SiO ₂ is laminated in four layers is deposited on the entire surface of the wafer. Here, the film thicknesses of ZrO ₂ and SiO ₂ are set to be a quarter of the laser oscillation wavelength λ on the vertical etching surface serving as the emission end face. Next, an n-side electrode 120 made of Ti / Al / Ni / Au is formed on a part of the n-type contact layer 112.
[0024]
(7) Next, the upper part of the p-type contact layer 118 is exposed, and a p-side electrode 121 made of Pt / Au is formed. Next, although not particularly illustrated, the back surface of the sapphire substrate 100 is mirror-polished so that the thickness of the substrate 100 is 150 μm, a Ti / Pt / Au film is deposited on the back surface of the sapphire substrate 100, and chips are formed by a cleavage method or a scribe method. Further, a layer obtained by metalizing Ti / Pt / Au or the like on a heat sink having high thermal conductivity such as Cu, cubic boron nitride, or diamond is thermocompression bonded using AuSn eutectic solder. The wiring for current injection uses Au wire.
[0025]
The laser shown in FIG. 1 formed by the above manufacturing method oscillated continuously at room temperature at an oscillation wavelength of 405 nm and an operating voltage of 4.2 V when the resonator length was 0.5 mm. The outgoing beam oscillated in the TE ₀₀ mode, and the full width at half maximum of the far-field image was vertical direction θ _⊥ = 8 ° and horizontal direction θ _// = 20 °, and an aspect ratio of 2.5 was obtained. The device lifetime at 50 ° C. and 30 mW drive was 5000 hours or more. Furthermore, in the laser of FIG. 1, the threshold current was as extremely low as 20 mA. This is about half of the conventional level. Further, the relative intensity noise from 20 ° C. to 80 ° C. is −140 dB / Hz or less, and the relative intensity noise characteristic is improved by about 10 to 20% compared to the conventional case.
[0026]
In the nitride semiconductor laser of FIG. 1 described above, since the groove 130 is provided, the relative noise intensity can be reduced. One of the reasons is analyzed because it is possible to reduce lateral leakage light. That is, in the nitride semiconductor laser, light is easily transmitted in the lateral direction on the waveguide surface including the active layer 115 and the guide layers 114 and 116 as described above. And light becomes easy to permeate | transmit, when it goes to a low substance from a substance with a high refractive index. Therefore, even in the laser of FIG. 1, the light generated in the active layer 115 passes from the waveguide surface (refractive index of about 2.5) to the insulating film 119 (refractive index = about 1.4 to 2.1) in the groove. Is easy to progress. However, in the laser shown in FIG. 1, light hardly travels from the insulating film 119 (refractive index = about 1.4 to 2.1) in the groove 130 to the outer waveguide surface (refractive index = about 2.5). . That is, light is likely to be reflected outside the groove 130. For this reason, the light transmitted to the outside of the chip from the lateral direction can be reduced, and the leakage light can be reduced. As a result, the base of the light that becomes the noise of the far-field image is reduced, and a single-peak spectrum of only the fundamental mode light is obtained. Therefore, not only the aspect ratio approaches 1, but also the relative noise intensity can be reduced.
[0027]
On the other hand, in the conventional laser (FIG. 2), the light generated in the active layer 215 travels in the order of the waveguide surface (refractive index = about 2.5) and air (refractive index = 1). It was easy to transmit light.
[0028]
However, it is not always possible to reduce noise simply by reducing leakage light. For this reason, it is unexpected for an ordinary engineer that noise can be reduced by forming the groove 130 as shown in FIG. That is, as a method for reducing leakage light, there is a method of forming a highly reflective coating film on the left and right surfaces of the conventional laser (FIG. 2). Alternatively, a method of filling the laser groove 130 of FIG. However, if such a highly reflective coating film is formed, a resonance mode appears in the lateral direction. And noise will generate | occur | produce by this resonance mode. For this reason, reducing leakage light and reducing noise do not necessarily match. However, according to the experiments of the present inventors, the laser of FIG. 1 was able to reduce noise by reducing leakage light. The inventor considers the reason as follows. That is, in the laser of FIG. 1, most of the light emitted in the direction perpendicular to the laser emission direction (lateral direction in the figure) is reflected in the inner direction outside the groove 130. The reflected light is confined in the low refractive index layer of the groove 130 or bent by the groove 130 and confined by the cladding layers 114 and 116. Therefore, the spontaneous emission light incident on the groove 130 does not contribute to the oscillation and does not leak outside the chip.
[0029]
In the nitride semiconductor laser of FIG. 1, current can be injected with high density and high efficiency near the center of the quantum well active layer 215. For this reason, the threshold current can be lowered.
[0030]
In the nitride semiconductor laser shown in FIG. 1, the entire width of the active layer 115 can be set to 200 μm, which is the same as the conventional one. For this reason, thermal resistance hardly increases as compared with the conventional laser.
[0031]
Further, the nitride semiconductor laser of FIG. 1 can directly modulate up to about 10 GHz. This is because the formation of the trench 130 narrows the pn junction area and reduces the junction capacitance. In addition, since the pn junction area is constrained to be narrow, it contributes to prevention of leakage current from the mesa structure in which high carriers are injected during laser oscillation, so that the operating current can be reduced and the life can be extended.
[0032]
Next, the width of the groove 130 will be examined. That is, in the nitride semiconductor laser shown in FIG. 1, the width of the groove 130 is set to 1 μm. However, since the groove 130 can be manufactured with another width, this width will be examined. As described above, when the groove 130 is filled with the highly reflective coating film, a resonance mode appears in a direction perpendicular to the emission direction (lateral direction in the figure), which causes noise, which is not preferable. Therefore, it is preferable that the width of the groove 130 is a thickness that is difficult to reflect, that is, λ / 2 or more that easily absorbs leaked light, where λ is the center wavelength of spontaneously emitted light from the active layer 115. In addition, if the width of the groove 130 is too wide, a high reflection coating film may be formed on the side surface of the groove 130 when the embedding process of the groove 130 and the end face high reflection coating film forming process are performed simultaneously. For this reason, the width of the groove 130 is desirably 2 μm or less. However, when the material covering the groove is a single layer or not a highly reflective coating film, it may be 2 μm or more as long as it is λ / 2 or more.
[0033]
In the nitride semiconductor laser described above, the ZrO ₂ / SiO ₂ insulating film 119 is used as the filling material for the groove 130, and this filling material contains at least one of ZrO ₂ , SiO ₂ , TrO ₂ , and AlGaN. Things can also be used. Further, it is possible to use the groove 130 with air or vacuum without embedding the groove 130.
[0034]
The nitride semiconductor laser described above is not limited to the present embodiment, and the composition and thickness of each semiconductor layer can be changed. For example, the n-type contact layer 112 can be made of AlGaN instead of GaN. In this case, the trench 130 can be formed partway through the n-type contact layer 112. This is because when the n-type contact layer is made of AlGaN, the n-type contact layer 112 becomes a clad layer with respect to the active layer 115, so that it is difficult to form an anti-waveguide structure. This is because even if the groove 130 is formed halfway, the light does not bleed out in the lower part of the figure. However, it goes without saying that the groove 130 should not penetrate the n-type contact layer 112. This is because if the n-type contact layer is penetrated, the n-side electrode 120 and the active layer 115 are electrically disconnected. For example, the n-type superlattice clad layer 113 and the p-type superlattice clad layer are not limited to the superlattice structure, and may be a clad layer containing AlGaN.
[0035]
Further, the nitride semiconductor laser described above may have a structure with reverse conductivity. Further, steps such as the order of etching are not limited to the present embodiment. Further, the substrate is not limited to sapphire, but may be a GaN substrate, or a GaN substrate is more preferable if the GaN substrate can be easily obtained in the future. Further, the laser is not limited to the edge emitting laser, and may be a laser having another structure such as a surface emitting laser. Furthermore, in addition to the light emitting element, it can be applied to an optical device such as a light receiving element.
[0036]
【The invention's effect】
According to the present invention, since a groove penetrating the active layer is provided in the ridge structure nitride semiconductor laser, a laser having a low threshold current and a low noise characteristic can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a nitride semiconductor laser according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a conventional nitride semiconductor laser.
[Explanation of symbols]
100 Sapphire substrate 110 Buffer layer 111 SiO ₂ mask 112 n-type contact layer 113 n-type superlattice cladding layer (first conductivity type semiconductor layer)
114 n-side guide layer 115 active layer 116 p-side guide layer 117 p-type superlattice clad layer 117A first p-type clad layer (first second conductivity type semiconductor layer)
117B Second p-type cladding layer (second second conductivity type semiconductor layer)
118 p-type contact layer 119 ZrO ₂ / SiO ₂ insulating film 120 n-side electrode (first electrode)
121 p-side electrode (second electrode)
130 groove

Claims (6)

A first conductivity type semiconductor layer made of a gallium nitride compound semiconductor;
An active layer formed on the first conductivity type semiconductor layer and made of a gallium nitride compound semiconductor;
A first second-conductivity-type semiconductor layer formed on the active layer and made of a gallium nitride compound semiconductor;
A striped second second conductive semiconductor layer having a mesa structure made of a gallium nitride compound semiconductor and provided in a part on the first second conductive semiconductor layer;
With
On both sides of the second second conductivity type semiconductor layer having the mesa structure, at least the first second conductivity type semiconductor layer and the active layer are penetrated in parallel to the second second conductivity type semiconductor layer. Ri Na pair of grooves are formed on,
The nitride semiconductor laser , wherein the width of the groove is not less than a half of the emission wavelength from the active layer and not more than 2 μm .   2. The nitride semiconductor laser according to claim 1, wherein the active layer is an active layer having a multiple quantum well structure. The relationship between the bottom width W1 of the striped second second-conductivity-type semiconductor layer and the distance W2 from the second second-conductivity-type semiconductor layer to the groove is:
W1 ≦ W2
The nitride semiconductor laser according to claim 1 or 2, wherein   4. The groove according to claim 1, wherein the groove is filled with a material having a refractive index lower than that of the first conductive semiconductor layer and the first second conductive semiconductor layer. The nitride semiconductor laser described in 1. The nitride semiconductor laser according to claim 4, wherein the material having a low refractive index includes at least one of ZrO ₂ , SiO ₂ , TiO ₂ , and AlGaN. A substrate,
A first conductivity type semiconductor contact layer made of GaN formed on the substrate;
A first conductive type semiconductor cladding layer formed on the first conductive type semiconductor contact layer and containing AlGaN;
An active layer of a multiple quantum well structure formed on the first conductivity type semiconductor cladding layer, including InGaN, and emitting light of wavelength λ by current injection;
A first second-conductivity-type semiconductor clad layer formed on the active layer and containing AlGaN;
A second second-conductivity-type semiconductor clad layer formed on a part of the first second-conductivity-type semiconductor clad layer, having a striped mesa structure with a bottom width W1, and including AlGaN;
A second conductivity type semiconductor contact layer made of GaN formed on the striped second second conductivity type semiconductor clad layer;
A first electrode formed in electrical connection with the first conductivity type semiconductor contact layer;
A second electrode formed in electrical connection with the second conductivity type semiconductor contact layer,
On both sides of the striped second second-conductivity-type semiconductor clad layer, the first second-conductivity is disposed at a position parallel to the second second-conductivity-type semiconductor clad layer and separated by W2 (W1 ≦ W2) or more. A groove having a width of λ / 2 (λ is a light emission wavelength from the active layer) and a width of 2 μm or less is formed so as to reach the middle of the first conductive semiconductor clad layer through the active semiconductor layer and the active layer. And
The first second-conductivity-type semiconductor clad layer, the second second-conductivity-type semiconductor clad layer, and a material having a refractive index lower than that of the first-conductivity-type semiconductor clad layer, and ZrO ₂ , SiO ₂ , TiO _2. A nitride semiconductor laser, wherein the groove is filled with a material containing at least one of AlGaN.

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