JPH09139543A - Semiconductor laser element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a semiconductor laser having a light emitting active layer region composed of GaInN/AlGaN, at a low threshold value. SOLUTION: A GaN buffer layer 2 and an N-type GaN optical waveguide layer 3 are grown on a substrate 1, and an insulating mask 14 is formed. Again the N-type GaN optical waveguide layer 3, an N-type AlGaN optical waveguide layer 4, a strain compensation multiquantum well active layer 5, a P-type AlGaN optical waveduide layer 6, a P-type GaN optical waveguide layer 7 and a P-type GaInN contact layer 8 are selectively grown. The strain compensation multiquantum well active layer 5 is formed by joining a quantum barrier layer of undoped Al0.10 Ga0.90 N to a quantum well layer of undoped Ga0.20 In0.80 N. By constituting a light emitting active layer as the strain compensation structure by the quantum well layer of GaInN and a quantum barrier layer of AlGaN, an energy barrir of In composition of the quantum well layer and the AlGaN quantum barrier layer is increased. Thereby a laser element is obtained wherein electron and positive hole carriers are sufficiently confined in the quantum well layer, generation efficiency of optical gain is high, and operation at a low threshold value is possible up to a high temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device suitable for optical information processing or optical application measurement.

[0002]

2. Description of the Related Art As a conventional manufacturing technique, for example, regarding a blue light emitting diode element, the element structure constituting the element is applied physics letter magazine, 1994, 64.
Volume, 1687-1689 (Appl. Phys. Lett., 64, 1687-1689 (19
94).) And a light emitting active layer using a GaInN / GaN / AlGaN material is shown.

[0003]

In the prior art disclosed by the above-mentioned journals, reference is made to the structure of a light emitting active layer suitable for a blue light emitting diode made of a nitrogen-based material. However, it does not show a specific measure for the light emitting active layer for improving the light emitting efficiency of the light emitting device, and does not describe the details of the active layer structure that produces a larger optical gain at a low injection current. Moreover, no clear measure for carrier confinement for lasing at a low threshold value is described.

An object of the present invention is to provide an element structure suitable for improving the light emission efficiency of the light emitting element having the structure disclosed in the above journals, for example.

[0005]

SUMMARY OF THE INVENTION The above-mentioned object of the present invention is as follows.
The crystal layer forming the light emitting active layer has a multiple quantum well structure with good crystallinity and good steepness of the hetero interface, and by forming the strain compensation type active layer region, a threshold value lower than that of the conventional one (that is, GaInN / AlGaN by lowering the injection current to the device)
This is achieved by oscillating a device made of a material system. Therefore, in the present invention, the light emitting active layer of the light emitting device is formed of GaIn.
A periodic heterostructure (structure in which different layers are double-bonded) composed of an N compressive strain quantum well layer and an AlGaN tensile strain quantum barrier layer, and the light emitting active layer is configured as a strain compensating multiple quantum well structure active layer To do. Further, the details of the light emitting active layer are specified to improve the effect of introduced strain and the effect of confining carriers on the generation efficiency of optical gain. This achieves a laser device that operates with low threshold and high efficiency.

To achieve the above object, the present invention configures a semiconductor laser device as described below.

In the present invention, the active layer is constituted by a multi-quantum well structure in which a quantum well layer and a quantum barrier layer are formed of a ternary or more mixed crystal semiconductor composed of at least three or more elements,
Moreover, the lattice strains to be introduced into the quantum well layer and the quantum barrier layer are set with opposite signs (that is, both layers are laminated so that the positive and negative lattice strain values of the adjacent quantum well layer and quantum barrier layer are opposite to each other). hand)
A strain-compensated multiple quantum well structure is used. The difference between positive and negative lattice strain values is, for example, compressive strain is applied to one layer,
It is realized by laminating both layers so as to apply tensile strain to the other layer. Further, the optical isolation confinement layer provided adjacent to the multiple quantum well structure is also composed of a crystal layer in which lattice strain is introduced, and a strain compensation type is provided in the entire active layer region including the multiple quantum well structure and the optical isolation confinement layer. And The light separation / confinement layer may be bonded to the quantum well layer on one surface and to the p-type or n-type optical waveguide layer on the other surface. By adopting the strain compensation type, a larger lattice strain is introduced into the quantum well layer, and especially for a nitrogen-based material having a carrier with a heavy effective mass, the band structure of the valence band is deformed to improve the effective mass. It becomes possible to use a light hole carrier.

In a semiconductor laser device having a light emitting active layer made of a III-V group compound, if the quantum well layer contains In, the light emitting efficiency is improved. This also applies to a nitride material type semiconductor laser device (comprising a III-V group compound containing nitrogen as a V group element). Further, in order to form the light emitting active layer of the nitride-based semiconductor laser device with good crystallinity (defect-free), it is desirable to grow the light emitting active layer on the substrate or film made of GaN (for reference, the substrate or film). If contains Al, defects are likely to occur in the light emitting active layer). When a quantum well layer made of GaInN crystal and a quantum barrier layer made of AlGaN crystal are grown on a GaN substrate or film, compressive strain is introduced into the former and tensile strain is introduced into the latter.
When the former film containing an element (In) with a larger atomic radius than Ga grows on the surface of the GaN crystal, the crystal lattice of this film extends in the growth direction, so it must be lattice-matched with the GaN crystal even if it contains In. You can In other words, the former film is formed as a crystal having a shape compressed from the direction perpendicular to the growth direction (that is, the side surface of the film). At this time, compressive strain is applied to the former film, that is, the GaInN crystal. The latter membrane, namely G
The film containing an element (Al) having a smaller atomic radius than a is the opposite of the former. This is clear considering the latter film grown on the surface of the GaN crystal. The latter film grows while being lattice-matched with the GaN crystal by shrinking its crystal lattice in the growth direction. Therefore, the latter film is formed as a crystal having a shape that is pulled in a direction perpendicular to the growth direction, and tensile strain is applied to this film, that is, the AlGaN crystal. It goes without saying that when the former film and the latter film are directly bonded, compressive strain is applied to the former film and tensile strain is applied to the latter film.

Up to this point, for the sake of understanding, the quantum well layer is Ga
Although the quantum barrier layer is formed of an InGaN crystal and the quantum barrier layer is formed of an AlGaN crystal, the quantum well layer of the present invention has an atom whose atomic radius is larger than that of other layers (in other words, an atom whose mass is large). The quantum barrier layer is characterized in that it contains many atoms having a small atomic radius (in other words, atoms having a small mass) with respect to the quantum well layer. It can be said that the quantum well layer is larger than the quantum barrier layer in terms of the average mass of atoms constituting a unit cell of a crystal. When growing both layers (crystal films), it is important to keep the film thickness below the critical film thickness (the maximum film thickness value at which crystal defects due to strain do not occur).

In the semiconductor laser device of the present invention, the multi-quantum well structure, which is the light emitting active layer, is composed of a ternary or more mixed crystal semiconductor without using a binary compound semiconductor, so that the lattice strain in the light emitting active layer is reduced. Increase mitigation. By compensating for strain in the entire light emitting active layer region, for example, GaInN
It becomes possible to introduce a larger In composition in the compressive strain quantum well layer. That is, a large optical gain can be realized by the two effects that a larger strain effect can be utilized and the potential well of the quantum well layer can be increased. Moreover, since an AlGaN layer having a large forbidden band width and a large conduction band offset can be used for the quantum barrier layer, it is possible to set the energy barrier to the quantum well layer sufficiently high. Therefore, the effect of carrier confinement in the multiple quantum well structure can be further improved. Further, in the strain compensation type active layer region, the crystallinity can be remarkably improved as compared with the case of the conventional single active layer. The strain-compensated multi-quantum well structure is effective in that the lattice strain of the quantum well layer can be introduced and utilized more, and strain can be compensated in the entire active layer region to maintain good crystallinity. . By forming a quantum well layer and a quantum barrier layer with a ternary or more mixed crystal semiconductor composed of at least three or more elements, flexibility of lattice strain relaxation is provided. Specifically, in the nitride material system, a GaInN crystal layer having a compressive strain introduced into the quantum well layer is used, and an AlGaN crystal layer having a tensile strain introduced into the quantum barrier layer. By compensating for the strain in the entire light emitting active layer region, the In composition of the quantum well layer is largely introduced to increase the depth of the potential well, and the energy barrier can be set higher by the Al composition of the quantum barrier layer. It is possible to achieve a laser device having a high gain generation efficiency in which the carriers in the well layer are sufficiently confined and the optical gain is not saturated even at the time of high injection. As a result, stable laser oscillation can be obtained up to a high temperature above room temperature. Further, in the strain-compensated multiple quantum well structure of the nitride semiconductor according to the present invention, the GaInN quantum well layer requiring low temperature growth is repeatedly covered with the AlGaN quantum barrier layer which is stable at high temperature. It is possible to prevent the GaInN crystal layer from re-separating during the growth. This is because GaInN grows when an AlGaN quantum barrier layer is grown in the fabrication of a semiconductor laser device.
This is based on the requirement of film forming conditions that the substrate temperature is made higher than that at the time of growing the quantum well layer (deterioration of crystallinity at low temperature growth). In Group III atoms, In, Ga, and Al are evaporated in the order of heating, and the GaInN layer in the AlGaN layer grows.
Although the desorption of In was a problem, in the structure according to the present invention, since the already formed GaInN quantum well layer has a shape covered with the AlGaN quantum barrier layer, the desorption of In can be suppressed. That is, with the strain-compensated multiple quantum well structure of the present invention, the crystallinity of the quantum well layer and the abruptness of the hetero interface or composition could be favorably maintained in the order of one atom. Furthermore, strain compensation is performed including the light separation / confinement layer (it is configured as a light separation strain layer), and good crystallinity can be secured in the entire light emitting active layer region.

In the active layer having the multiple quantum well structure, the carrier injection efficiency must be taken into consideration. Particularly, in a nitride semiconductor having carriers with a large effective mass, it is necessary to sufficiently improve carrier transport and carrier trapping in each quantum well layer. Therefore, in the present invention, not only the quantum well layer and the quantum barrier layer shown in FIG. 1 are repeated, but also the structure having the quantum barrier layer in at least two stages shown in FIGS. It was devised to improve carrier capture in the layer. According to this, a lower threshold operation of the device is possible than in the case of FIG. 1, and the threshold current can be reduced from 2/3 to 1/2.

As described above, the strain-compensated multiplex resonator having good crystallinity, good steepness of the hetero interface in the order of atomic layer, good carrier confinement at higher temperatures, less saturation of optical gain, and improved gain generation efficiency. Ga as a quantum well structure
We have obtained a laser device that realizes laser oscillation of the InN / AlGaN material system at a low threshold and operates up to room temperature or higher.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 An embodiment of the present invention will be described with reference to FIG. First (0001) C
A GaN buffer layer 2 is grown on a sapphire (α-Al ₂ O ₃ ) substrate 1 having a surface at a temperature of 450 to 550 ° C. by a metal organic chemical vapor deposition method, and n-type Ga is grown at a growth temperature of 1000 to 1100 ° C.
N optical waveguide layer 3, n-type Al _α Ga _1-α N (α = 0.25) optical waveguide layer 4,
Undoped Al _α Ga _1-α N (α = 0.10) Optical isolation confinement layer and undoped Al _α Ga _1-α N (α = 0.10) Tensile strain quantum barrier layer and undoped Ga _1-β In _β N (β = 0.20) A strain compensation multi-quantum well active layer 5, which is a compressive strain quantum well layer, a p-type AlGaN optical waveguide layer 6, a p-type GaN optical waveguide layer 7, and a p-type GaInN contact layer 8 are provided. At this time, the strain compensation multiple quantum well active layer 5 is
The structure shown in was used. In the formation of the strain-compensated multi-quantum well active layer 5, especially when the undoped Al _α Ga _1-α N layer is formed on the undoped Ga _1-β In _β N layer, the desorption of In is performed if it is performed in an ammonia atmosphere. Can be suppressed. Further, the p-type optical waveguide layer 6, the p-type optical waveguide layer 7 and the p-type contact layer 8 are doped with a p-type impurity Mg, and the p-type optical waveguide layer 6 and the p-type optical waveguide layer 7 are Set within the range of 5 × 10 ^{17 to} 2 × 10 ¹⁸ / cm ³ , p
For the mold contact layer 8, it was set in the range of 5 × 10 ¹⁸ to 2 × 10 ¹⁹ / cm ³ . Next, as shown in FIG. 4, a part of the crystal layer is removed by photolithography and etching until the layer 3 is reached. After that, the insulating film 9 is provided and the stripe direction is formed in the direction parallel to the (11-20) A plane of the substrate 1. Further, the p-side electrode 10 and the n-side electrode 11 are vapor-deposited by lithography. Finally, the substrate is cleaved in the direction perpendicular to the optical waveguide stripe to obtain the element cross section shown in FIG.

According to this embodiment, since the lattice strain is compensated in the active layer structure, it is possible to introduce the In composition of the GaInN quantum well layer to a greater extent than in the case where the strain is not compensated, and the depth of the potential well is increased. You can take big. Furthermore, since the AlGaN crystal layer, which has a large forbidden band width and a large conduction band offset, is used as the quantum barrier layer, the energy barrier can be set higher. As a result, a laser device was obtained that operates well up to room temperature or higher at a low threshold value, in which carriers in the quantum well layer, particularly electron carriers are sufficiently confined, and the efficiency of generating optical gain is high. Further, in the strain-compensated multi-quantum well structure, the GaInN quantum well layer, which needs to be grown at low temperature, will be covered by the AlGaN quantum barrier layer which is stable at high temperature. The crystallinity of the compressive strained quantum well layer and the abruptness of the composition hetero interface can be maintained well. Further, since the strain compensation type multiple quantum well structure is provided, the crystallinity can be set well in the entire light emitting active layer region. In this example, a gain waveguide structure for guiding a transverse mode by providing a gain difference in the lateral direction of the active layer is provided, and an element that oscillates a laser in an oscillation wavelength range of 410 to 430 nm was obtained.

Embodiment 2 Another embodiment of the present invention will be described with reference to FIG. A device is manufactured in the same manner as in Example 1, but after the layer 7 is provided, the layer 7 is removed by photolithography and etching until the layer 6 is reached to form a ridge stripe. Next, the n-type GaN current confinement layer 12 is selectively grown using the insulating film mask. After removing the insulating film mask, the p-type GaN buried layer 13 and the p-type GaInN contact layer 8 are crystal-grown. Next, both sides of the ridge stripe structure are removed to the layer 3 by photolithography and etching as shown in FIG. After that, an element is manufactured in the same manner as in Example 1, and the element cross section shown in FIG. 5 is obtained.

According to the present embodiment, a ridge stripe structure having a refractive index guiding structure for stably guiding the fundamental transverse mode can be manufactured by providing an actual refractive index difference in the lateral direction of the active layer. Working at a lower threshold than Example 1, Example 1
Compared with, the threshold current was reduced to 1/3 to 1/5. The oscillation wavelength was in the blue-violet wavelength range of 410 to 430 nm.

Embodiment 3 Another embodiment of the present invention will be described with reference to FIG. First, the layers up to layer 3 are provided in the same manner as in Examples 1 and 2. Next, the selective growth insulating film mask 14 is formed by photolithography and etching. Then, n-type GaN optical waveguide layer 3, n-type A
lGaN optical waveguide layer 4, undoped Al _α Ga _1-α N (α = 0.10) Tensile strain optical isolation confinement layer and undoped Al _α Ga _1-α N (α = 0.10)
Tensile strain quantum barrier layer and undoped Ga _1-β In _β N (β = 0.20)
Strain-compensated multiple quantum well active layer composed of compressive strained quantum well layer 5, p-type AlGaN optical waveguide layer 6, p-type GaN optical waveguide layer 7, p-type Ga
The InN contact layer 8 is selectively grown. Then, the insulating film 9
And p-side electrode 10 and n are formed by lithography.
The pattern of the side electrode 11 is formed by vapor deposition. Further, by cleaving the substrate in a direction perpendicular to the waveguide, the device cross section shown in FIG. 6 is obtained.

According to this embodiment, since a large difference in actual refractive index can be provided in the lateral direction of the active layer, guided light can be stably propagated, and a fundamental transverse mode having a small aspect ratio and a circular shape can be guided. B having a refractive index guiding structure
An H stripe structure could be produced. This device is capable of lower threshold operation than the first and second embodiments, and has a threshold current of the second embodiment.
We obtained an element that is reduced from 1/2 to 1/3 compared to. The oscillation wavelength was in the blue-violet wavelength range of 410 to 430 nm. A BH stripe structure that stably guides the fundamental transverse mode by the difference in real refractive index was produced. In this device, the difference in the refractive index in the lateral direction of the active layer can be made larger than that of the device of Example 1, so that the guided light can be stably propagated. Furthermore, since the current constriction effect is large, low threshold operation was possible. The threshold current could be further reduced from 1/2 to 1/3 as compared with Example 2. The oscillation wavelength is 410 to 430n in the blue-violet wavelength range.
m.

Embodiment 4 Another embodiment of the present invention will be described. In this embodiment, the first embodiment
2 to 3 are produced in the same manner, but the structure of FIG. 2 or FIG. 3 in which the quantum barrier layer is provided in at least two stages with respect to the strain compensation multiple quantum well active layer 5 is introduced. Others
The device structures of Examples 1 to 3 were manufactured in the same manner, and respective device cross sections were obtained.

According to the present embodiment, a device structure similar to those of the embodiments 1, 2 and 3 was produced, and the light emitting active layer was changed from the structure of FIG. 1 to the structure of FIG. The threshold current can be reduced from 2/3 to 1/2 as compared with the respective examples. The oscillation wavelength was in the blue-violet wavelength range of 410 to 430 nm.

Embodiment 5 Another embodiment of the present invention will be described. In this example, instead of the sapphire (α-Al ₂ O ₃ ) substrate, the substrate 1 was a hexagonal Wurtzi system.
As an n-type silicon carbide (α-SiC) having a te structure and a substrate plane orientation of (0001) C plane, an n-type GaN buffer layer is provided thereon, and then the element structures of Examples 1 to 3 are formed. It produced similarly and obtained each element cross section. According to the present embodiment, since the substrate is n-type conductive, the n-side electrode is vapor-deposited on the rear surface of the substrate, and the n-side electrode on the lower surface of the substrate is transferred from the p-side electrode on the upper surface of the substrate through the nitride semiconductor. It was possible to pass a current through. As a result, when the chip element is assembled, it is possible to mount the joint part downward, so that the heat dissipation can be significantly improved. In this example, a laser element that operates at a higher temperature than the above examples was obtained.

[0022]

According to the present invention, particularly in a III-V nitride semiconductor AlGaInN material, a GaInN compressive strain quantum well layer and an Al
By introducing a strain-compensated multi-quantum well structure formed by repeating GaN tensile strain quantum barrier layers into the active layer, the depth of the potential well can be increased and the energy barrier can be set higher. We have achieved a laser device with high gain generation efficiency, in which the optical gain is not saturated even during high injection. Further, in the strain-compensated multi-quantum well structure according to the present invention, the GaInN quantum well layer that requires low-temperature growth is repeatedly covered with the AlGaN quantum barrier layer that is stable at high temperature. It was possible to prevent re-desorption of the GaInN crystal layer and maintain the crystallinity of the quantum well layer and the abruptness of the hetero-interface and composition on the order of one atom. Furthermore, strain compensation is performed including the light separation and confinement layer, and good crystallinity can be secured in the entire light emitting active layer region. As a result, a laser device which operates at a low threshold and oscillates up to a high temperature above room temperature was obtained. In this embodiment, in the lateral direction of the active layer, a gain guiding structure for providing a gain difference and guiding a lateral mode and a refractive index guiding structure for providing a real refractive index difference and stably guiding a fundamental lateral mode are provided. Was produced. The device with a refractive index guided structure operates at a lower threshold than the gain guided structure, and the threshold current is reduced from 1/3 to 1/5. Furthermore, the strain-compensated multiple quantum well structure is shown in FIG.
The threshold current is further reduced from 2/3 to 1/2 by introducing the structure of FIG. The oscillation wavelength of this device was in the range of 410 to 430 nm.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the conduction band and valence band band structures of a strain-compensated multiple quantum well structure active layer region.

FIG. 2 is a schematic diagram showing the conduction band and valence band band structures of a strain compensation type multiple quantum well structure active layer region.

FIG. 3 is a schematic diagram showing the conduction band and valence band band structures of a strain-compensated multiple quantum well structure active layer region.

FIG. 4 is a sectional view of an element structure showing an embodiment of the present invention.

FIG. 5 is a cross-sectional view of an element structure showing another embodiment of the present invention.

FIG. 6 is a sectional view of an element structure showing another embodiment of the present invention.

[Explanation of symbols]

1 ... (0001) C-plane sapphire single crystal substrate, 2 ... GaN buffer layer, 3 ... n-type GaN optical waveguide layer, 4 ... n-type AlGaN optical waveguide layer, 5
... undoped GaInN / AlGaN strain compensation multiple quantum well structure active layer, 6 ... p-type AlGaN optical waveguide layer, 7 ... p-type GaN optical waveguide layer, 8
... p-type GaInN contact layer, 9 ... insulating film mask, 10 ...
p-side electrode, 11 ... N-side electrode, 12 ... N-type GaN current confinement layer, 13 ... P-type GaN buried layer, 14 ... Insulating film mask for selective growth.

Claims (15)

[Claims] 1. A light emitting device provided on a single crystal substrate, comprising:
A heterojunction double-junction structure having an optical waveguide layer having a large forbidden band width and an emission active layer having a small forbidden band sandwiched between them is provided, and the crystal layer provided on the substrate is a III-V group mixed crystal. And a compound semiconductor material, and at least the light emitting active layer is entirely formed of a ternary or more mixed crystal semiconductor containing two or more Group III elements or two or more Group V elements, A semiconductor laser device characterized by comprising a strained multiple quantum well structure in which a quantum well layer or a quantum barrier layer is repeatedly formed by a ternary or more mixed crystal semiconductor having lattice strain introduced. 2. The strain quantum well layer and the strain quantum barrier layer constituting the strained multiple quantum well structure light emitting active layer are introduced with lattice strains of at least opposite signs, and the lattice strain is compensated in the entire light emitting active layer. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is manufactured. 3. A lattice strain is introduced also into the light splitting / confining layers provided on both sides of the strained multiple quantum well structure light emitting active layer, and the strained multiple quantum well structure light emitting active layer and the light splitting and confining layer are included as a whole. 2. The semiconductor laser device according to claim 1, wherein the semiconductor laser device has a strain compensation type light emitting active region capable of compensating for lattice strain. 4. The strained quantum barrier layer in the strained multiple quantum well active layer has either compressive strain or tensile strain,
4. The semiconductor laser device according to claim 1, wherein the semiconductor laser device comprises a two-stage crystal layer in which compressive strain and compressive strain, tensile strain and tensile strain, or compressive strain and tensile strain are introduced. . 5. The III-V group semiconductor material forming the strained multiple quantum well active layer and the optical waveguide layer is made of a nitride-based mixed crystal or compound semiconductor, and is made of an AlGaInN material. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is a semiconductor laser device. 6. The semiconductor laser device according to claim 5, wherein the strained multiple quantum well active layer is formed by repeating a GaInN compressive strained quantum well layer and an AlGaN tensile strained quantum barrier layer. 7. The strained multiple quantum well active layer comprises a GaInN compressive strained quantum well layer and an AlGaN tensile strained quantum barrier layer having at least two stages in which the Al composition is changed stepwise, thereby providing the quantum well layer and the quantum well layer. 6. The semiconductor laser device according to claim 4, wherein the quantum barrier layers are alternately and repeatedly formed. 8. The strained multiple quantum well active layer comprises a GaInN compressive strained quantum well layer, a GaInN compressive strained quantum barrier layer having an In composition smaller than that of the quantum well layer, and an AlGaN tensile strained quantum barrier layer in at least two stages. 6. The semiconductor laser device according to claim 4, wherein the semiconductor laser device is formed of a quantum barrier layer provided in the above, and the quantum well layers and the quantum barrier layers are alternately and repeatedly formed. 9. The semiconductor laser device according to claim 5, wherein the optical isolation confinement layer is formed by using an AlGaN tensile strain crystal layer. 10. The single crystal substrate is a single crystal substrate having a hexagonal Wurtzite structure.
10. The semiconductor laser device according to any one of items 9 to 9. 11. The single crystal substrate has a Wurtzite structure.
11. The semiconductor laser device according to claim 10, which is a sapphire (α-Al ₂ O ₃ ) substrate having a (0001) C plane or silicon carbide (α-SiC) having a (0001) C face. . 12. When the optical waveguide structure is provided on the hexagonal Wurtzite structure substrate, the direction in which the waveguide is formed is parallel to or perpendicular to the (11-20) A plane of the substrate. The semiconductor laser device according to claim 5, wherein the semiconductor laser device is set in a direction. 13. The semiconductor laser device according to claim 5, wherein a p-type GaInN crystal layer is set in the p-type contact layer in contact with the p-side electrode. 14. The p-type GaInN contact layer in contact with the p-side electrode is provided with an activated carrier concentration of at least 5 × 10 ¹⁸ / cm ³ or more, and 5 × 10 ^{18 to} 5 × 10 ¹⁹ / cm
14. The semiconductor laser device according to claim 13, wherein the semiconductor laser device can be arbitrarily set within the range of ³ . 15. The semiconductor laser device according to claim 5, wherein the p-type impurity generating the activated hole carrier concentration is doped with Mg.