JP2002344088A - Nitride semiconductor laser element and optical device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved nitride semiconductor laser element, having low threshold current density. SOLUTION: The nitride semiconductor laser element comprises a processing substrate 101, having grooves and hills formed on one main surface of a nitride semiconductor substrate, a nitride semiconductor substrate layer covering the grooves and the hills of the substrate, and a nitride semiconductor multilayer light-emitting structure having a quantum well layer or a light-emitting layer 106, having the quantum well layer and a barrier layer brought into contact with the well layer between n-type layers 103 to 105 and between p-type layers 107 to 110 on the substrate layer. A current constriction part of the multilayer light-emitting structure is formed in the laser element above a region, within the width of the hill separately by 1 μm or more from a center of the hill in a widthwise direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a nitride semiconductor laser device having an improved low threshold current density and an optical device including the same.

[0002]

2. Description of the Related Art In order to improve the light emission characteristics of a nitride semiconductor laser device, an uneven portion is formed on a GaN layer laminated on a sapphire substrate, and the uneven portion is covered with a GaN underlayer to be flat. Forming a gallium nitride based semiconductor laser device on a GaN coating layer is disclosed in
No. 4500. The publication also states that a sapphire substrate may be replaced with a GaN substrate.

[0003]

However, even in the nitride semiconductor laser device in which the sapphire substrate is replaced by a GaN substrate as in the above-mentioned prior art, there is a problem that the laser oscillation threshold current density is not sufficiently low. In. Accordingly, one of the main objects of the present invention is to provide a nitride semiconductor laser device having an improved low threshold current density.

[0004]

According to the present invention, a nitride semiconductor laser device includes a processed substrate including a groove and a hill formed on one main surface of a nitride semiconductor substrate; A nitride semiconductor underlayer covering a hill, and a nitride including a light emitting layer including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between the n-type layer and the p-type layer on the nitride semiconductor underlayer. A semiconductor multilayer light emitting structure, wherein a current confinement portion of the multilayer light emitting structure is formed at least 1 μm from the center in the width direction of the hill and above a region within the width of the hill.

The width of the hill is preferably in the range of 4 to 30 μm, and the width of the groove is preferably in the range of 2 to 30 μm.

The longitudinal direction of the groove or the hill is preferably substantially parallel to the <1-100> direction or the <11-20> direction of the crystal of the substrate.

The width of the hill is preferably wider than the width of the groove,
The depth of the groove is preferably in the range of 0.25 to 10 μm.

[0008] The nitride semiconductor underlayer is made of Si, O, Cl,
1 × 10 ^{17 to} 8 × 10 ¹⁸ / c with at least one of S, C, Ge, Zn, Cd, Mg and Be as an impurity
It is preferable that the content is within the range of m ³ .

The nitride semiconductor underlayer is made of Al _x Ga ₁ -xN
(0.01 ≦ x ≦ 0.15), and it is preferable that the impurities be contained in the range of ³ × 10 ^{17 to} 8 × 10 ¹⁸ / cm ³ .

The nitride semiconductor underlayer is made of In _x Ga ₁ -xN.
(0.01 ≦ x ≦ 0.18), and it is preferable that the impurities be contained in the range of 1 × 10 ¹⁷ to 5 × 10 ¹⁸ / cm ³ .

It is preferable that the quantum well layer contains at least one of As, P, and Sb.

The nitride semiconductor laser device as described above is
It can be preferably used in various optical devices.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of various embodiments according to the present invention, the meanings of some terms will be clarified in advance.

First, the "groove" means a stripe-shaped recess formed on one main surface of the nitride semiconductor substrate.
Means a stripe-shaped projection (see, for example, FIG. 2). Note that the cross-sectional shapes of the grooves and hills are not necessarily those shown in FIG.
The shape need not be rectangular as shown in (a) but may be, for example, a V-shape. In the drawings of the present application,
Lengths, widths, thicknesses, depths, and the like are appropriately changed for simplification and clarity of the drawings, and do not represent actual dimensional relationships.

[0015] The term "nitride semiconductor substrate", Al _x Ga _y I
_nz N (0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z ≦ 1; x + y
+ Z = 1). However, about 10% or less of the nitrogen element contained in the nitride semiconductor substrate is As,
It may be substituted with at least one of P and Sb (provided that the hexagonal system of the substrate is maintained). The nitride semiconductor substrate is made of Si, O, Cl,
At least one of S, C, Ge, Zn, Cd, Mg, and Be may be added.

The term "worked substrate" means a substrate having a groove and a hill formed on one principal surface of a nitride semiconductor substrate. The width of the groove and the width of the hill may have a fixed period or may have various widths. Also, regarding the depth of the grooves, all the grooves may have a certain depth,
It may have different depths.

[0017] The term "nitride semiconductor underlayer" means a nitride semiconductor film covering the processed _{substrate, Al x Ga y In z N} (0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z
≦ 1; x + y + z = 1). However, as in the case of the nitride semiconductor substrate, about 1% of the nitrogen element contained in this nitride semiconductor underlayer is
0% or less may be substituted with at least one of As, P, and Sb, and Si, O, Cl, S, C,
At least one of Ge, Zn, Cd, Mg, and Be may be added.

The term "light-emitting layer" means a layer including one or more quantum well layers or a plurality of barrier layers alternately stacked thereon and capable of producing a light-emitting effect. However, the light emitting layer having a single quantum well structure is composed of only one well layer,
Alternatively, it is composed of a laminate of a barrier layer / well layer / barrier layer.
Of course, the light emitting layer of the multiple quantum well structure includes a plurality of alternately stacked well layers and a plurality of barrier layers.

The “multilayer light emitting structure” means, in addition to the light emitting layer,
It means a structure further including an n-type layer and a p-type layer sandwiching it. The term “coated substrate” means an improved substrate including a processed substrate and a nitride semiconductor underlayer that covers the processed substrate (see FIG. 3).

The "current confinement portion" means a portion where a current is substantially injected into the light emitting layer via the p-type layer or the n-type layer, and the "current confinement width" means the width of the portion. For example, in the case of a semiconductor laser device having a ridge stripe portion as shown in FIG. 4A, the current confinement portion corresponds to the ridge stripe portion, and the current confinement width corresponds to the stripe width. Similarly, in the case of a semiconductor laser device having a current confinement layer as shown in FIG. 4B, the current confinement portion corresponds to a portion sandwiched between two current blocking layers,
The current confinement width corresponds to the current blocking interlayer width.

[Embodiment 1]

According to the nitride semiconductor laser device of the present invention,
A processed substrate including a groove and a hill formed on one main surface of the nitride semiconductor substrate is included. The current confinement portion of the nitride semiconductor multilayer light emitting structure included in this laser device is formed at an optimum position which is at least 1 μm away from the center in the width direction of the hill of the processing substrate and above a region within the width of the hill, Thereby, the threshold current density of the laser device can be reduced.

This optimum position where the current confinement portion is formed is effective only when a processed substrate made of a nitride semiconductor is used. This is because the nitride semiconductor underlayer grown on a processed substrate made of a substrate other than a nitride semiconductor (hereinafter, referred to as a heterogeneous substrate) has a larger thickness than that grown on a processed substrate of a nitride semiconductor. This is because they are subjected to strong stress strain. That is, the crystal distortion in the nitride semiconductor base layer covered with the processed heterogeneous substrate is not reduced as in the case of using the processed substrate of the nitride semiconductor. This is because the difference in thermal expansion coefficient between the processed heterogeneous substrate and the nitride semiconductor underlayer is much larger than that between the nitride semiconductor substrate and the nitride semiconductor underlayer. Therefore, when the nitride semiconductor substrate is replaced with a heterogeneous substrate, even if the current confinement portion is formed at a position corresponding to the optimum position according to the present invention, the crystal strain in the multilayer light emitting structure is the same as in the present invention. Is not relaxed.

Further, since the difference in thermal expansion coefficient between the processed heterogeneous substrate and the nitride semiconductor underlayer is much larger than that between the nitride semiconductor substrate and the nitride semiconductor underlayer, the nitride semiconductor underlayer is After formation, the heterogeneous substrate itself often warps. Then, if the dissimilar substrate itself warps, it becomes difficult to form the current confinement portion of the laser element at the target position with good reproducibility.

(About the formation position of the current confinement portion)

As a result of detailed studies by the present inventors, the threshold current density of the nitride semiconductor laser device depends on the position of the current confined portion formed on the coated substrate. It was found to change.

In FIG. 5, the horizontal axis of the graph represents the distance (μm) from the hill center c of the coated substrate to the ridge stripe end a in the width direction, and the vertical axis represents the reduction rate (%) of the laser oscillation threshold current density. ). Here, hill center c
The distance from the ridge center a to the ridge stripe end a (hereinafter, referred to as ca distance) is indicated by a positive value in the width direction from the hill center c and a negative value in the left direction. The reduction rate of the laser oscillation threshold current density is defined as the reduction rate of the oscillation threshold current density of a laser device manufactured using a coated substrate compared to a laser device manufactured using a normal nitride semiconductor substrate. Represents. That is, the range where the reduction rate is positive indicates that the threshold current density is reduced and improved, and the range where the reduction rate is negative indicates that the threshold current density is increased and deteriorated.

The structure and manufacturing method of the nitride semiconductor laser device measured in FIG. 5 were the same as those of the second embodiment described later. The ridge stripe width is 2 μm and the hill width L
Was 18 μm, the groove width G was 10 μm, and the groove depth H was 2.5 μm.

As can be seen from FIG. 5, the reduction rate of the threshold current density of the nitride semiconductor laser device in which the ridge stripe portion is formed above the hill is larger than that in the case where the ridge stripe portion is formed above the groove. Showed a tendency. A closer examination showed that c, even within the area above the hill,
If the ridge stripe portion is formed in a region where the -a distance is larger than -3 µm and smaller than 1 µm, the rate of reduction of the threshold current density is dramatically reduced, that is, the threshold current density is conversely increased. all right. Here, taking into account that the width of the ridge stripe portion is 2 μm,
If 3 μm is converted into the distance from the hill center c to the ridge stripe end b (hereinafter referred to as cb distance), the cb distance becomes −1 μm. That is, when at least a part of the ridge stripe portion of the nitride semiconductor laser element is formed so as to be included within a range of less than 1 μm in the width direction from the groove center c to the left and right, the reduction rate of the threshold current density is dramatically reduced. I do.

In a region where the reduction rate of the threshold current density is dramatically reduced (for example, 1 μm in the width direction from the center c of the groove).
m is referred to as a region I. That is,
The ridge stripe portion of the nitride semiconductor laser device is preferably formed so as to include the entire area (ab width) in a range above the region within the hill width and excluding the region I. In addition, as the region I, the left and right 2
It is more preferable to set the distance in a range of less than
More preferably, it is set to a range of less than μm. Here, an area above the hill width range and excluding the area I is referred to as an area II.

The above results are summarized in the schematic diagram of FIG. 6, and the above-mentioned regions I and II are shown in the coated substrate in the present invention. That is, in the coated substrate according to the present invention, the ridge stripe portion of the nitride semiconductor laser device is preferably formed above the region II.

It is not always clear why the effect of reducing the laser oscillation threshold current density changes depending on the formation position above the coated substrate. However, even when the width of the ridge stripe portion is other than 2 μm, the same tendency as the relationship shown in FIG. 5 is obtained.

The relationship between the formation position of the ridge stripe portion and the reduction rate of the threshold current density is shown in FIG.
The present invention is not limited to a nitride semiconductor laser device structure having a ridge stripe structure as shown in the schematic sectional view of FIG. For example, in the case of a nitride semiconductor laser device having a current blocking structure as shown in the schematic sectional view of FIG. 4B, the above-mentioned ridge stripe portion corresponds to a portion sandwiched between two current blocking layers. The width of the ridge stripe corresponds to the width of the current blocking layer. Using a more general expression, if the current confinement portion (the light emitting layer portion where the current is substantially injected) of the nitride semiconductor laser device exists above the region II shown in FIG. The effect of the present invention can be sufficiently obtained.

However, in the case of the nitride semiconductor laser device having the current blocking structure, the reduction rate of the threshold current density was lower than that of the device having the ridge stripe structure. Further, the nitride semiconductor laser device having the current blocking structure has a large decrease in the yield due to the occurrence of cracks as compared with the device having the ridge stripe structure. Although these causes are not necessarily clear, it is thought that there is a problem in the step of crystal-growing the nitride semiconductor layer again on the current blocking layer in which the current constriction is formed. That is, in the process, in order to form a current confinement portion in the current blocking layer, during the formation of the multilayer light emitting structure, the substrate is once taken out of the crystal growth apparatus into a room temperature atmosphere, and then loaded again into the crystal growth apparatus and The remaining part of the light emitting structure is about 10
A crystal is grown at a temperature of 00 ° C. By giving a thermal history with a sharp temperature difference during the formation of the multilayer light emitting structure,
It is considered that crystal strain increases in the multilayer light emitting structure and cracks occur.

(About hill width)

The width of the hill formed on the processed substrate is preferably 4 μm or more and 30 μm or less, and more preferably 13 μm or more and 25 μm or less. The lower and upper limits of such hill width were estimated as follows. When the current confinement portion of the nitride semiconductor laser device is formed above the hill width, the lower limit of the hill width depends on the width of the current confinement portion (current confinement width). From the viewpoint of the reduction rate of the laser oscillation threshold current density described above, the current constriction portion is formed in the region II.
(See FIG. 6). Therefore, the lower limit of the hill width needs to be at least wider than the current constriction width. Since the current confinement width can be formed in the range of about 1 to 3.5 μm, the lower limit of the hill width is the width 2 of the region I.
It is estimated that it must be at least 4 μm, which is the sum of μm and the stripe width (1 μm) × 2. A more preferable lower limit of the hill width is 13 which is obtained by adding the enlarged width 6 μm of the region I and the stripe width (3.5 μm) × 2.
It is estimated that it is not less than μm.

On the other hand, there is no particular limitation on the upper limit of the hill width. However, the larger the hill width, the smaller the proportion of the region occupied by the grooves formed in the processed substrate, so that the effect of alleviating crystal strain is reduced and the crack generation rate is increased. Therefore, the upper limit of the hill width is preferably 30 μm or less, and more preferably 25 μm or less.

The hill width is preferably wider than the width of the groove formed in the processing substrate. This is because the most preferable region II where the current confined portion can be formed is widened, and many nitride semiconductor laser devices can be formed there.

(About groove width)

The lower limit and the upper limit of the groove width are 3 μm or more at 2 μm or more.
0 μm or less, preferably 5 μm or more and 25 μm
m is more preferable. That is, when the groove width is 2
If it is smaller than μm, the effect of reducing the threshold current density did not appear even if the current constriction was formed above the region II.
On the other hand, when the groove width became 5 μm or more, the reduction effect began to become remarkable. The upper limit of the groove width is not particularly limited, but the groove width is preferably 30 μm or less, and 25 μm or less in order to completely cover the groove formed on the processed substrate with the nitride semiconductor base layer. More preferably, there is.

(About groove depth)

FIG. 7 shows the relationship between the groove depth H (μm) and the reduction rate (%) of the laser oscillation threshold current density. The structure and manufacturing method of the nitride semiconductor laser device measured in FIG. 7 were the same as those of the second embodiment described later, and the hill width, groove width, and ridge stripe width were 18 μm, 10 μm, and 2 μm, respectively. In addition, the ridge stripe portion is c from the hill center c.
The -a distance was formed at a position of 4 μm (see FIG. 5).

As can be seen from FIG. 7, the groove depth H is about 0.
When it is within the range of 25 μm or more and 10 μm or less, the effect of reducing the laser oscillation threshold current density can be obtained. When the groove depth H is 0.75 μm or more and 5 μm or less, the effect of reducing the threshold current density becomes more apparent, and when the groove depth H is 1.5 μm or more, 4 μm.
If it is below, the reduction effect becomes more remarkable.

Incidentally, the relationship between the groove depth and the reduction rate of the laser oscillation threshold current density can show the same tendency as in FIG. 7 as long as the current confinement portion is formed above the region II.

(About the longitudinal direction of the groove)

The longitudinal direction of a groove formed in a nitride semiconductor substrate having a {0001} C plane as a main surface is <1-10
0> direction is most preferable, and <11-2.
It was then preferred to be parallel to the 0> direction. Even if the longitudinal direction of the groove in these specific directions had an opening angle of about ± 5 degrees in the {0001} C plane, there was no substantial effect.

The advantage of forming a groove along the <1-100> direction of the nitride semiconductor substrate is that the effect of suppressing crystal distortion and crack generation is very high. When a nitride semiconductor base layer is grown in a groove formed along this direction, the {11-20} is mainly formed on the side wall surface of the groove.
As the surface grows, the grooves are covered with a nitride semiconductor underlayer. Since the {11-20} side wall surfaces are perpendicular to the main surface of the substrate, the grooves are covered with the nitride semiconductor underlayer while having a substantially rectangular cross section. That is,
It is difficult for the nitride semiconductor underlayer to grow on the bottom surface of the groove, and the groove is covered from the side wall of the groove. Since the nitride semiconductor underlayer grows sufficiently in a direction parallel to the main surface of the substrate (hereinafter, referred to as lateral growth), it is considered that the effect of suppressing crystal distortion and crack generation becomes extremely high.

On the other hand, the nitride semiconductor substrate <11-20>
The advantage of forming the groove along the direction is that when the groove is filled with the nitride semiconductor base layer, the surface morphology of the base layer is good. When the nitride semiconductor underlayer grows in the groove formed along this direction, the {1-101} plane mainly grows on the side wall surface of the groove, and the groove is covered with the nitride semiconductor underlayer. Is done. This 1-10
1｝ The side wall surface is very flat, and the edge where the side wall surface contacts the hill top surface is also very steep. Therefore, <11
The groove formed along the -20> direction is covered with the nitride semiconductor underlayer almost without meandering as seen from above as shown in FIG. 2B. The surface morphology of the nitride semiconductor underlayer coated in this way can be very good. If the surface morphology of the nitride semiconductor underlayer is good, it is preferable because the device failure of the nitride semiconductor laser device having the current constriction formed above the region II of the underlayer is reduced.

Although the above-mentioned hills or grooves are all striped, it is preferable that the hills or grooves be striped in the following points. That is, the current confinement portion of the nitride semiconductor laser device is mainly in a stripe shape, and if the above-described preferable current confinement portion forming region (region II) is also in a stripe shape, the current confinement portion is formed in the preferable region II. It becomes easy to insert.

(Regarding Nitride Semiconductor Underlayer)

As the nitride semiconductor underlayer for covering the processing substrate, for example, a GaN film, an AlGaN film, an InGaN
A film or the like can be used. Further, Si, O, Cl, S, C, Ge, Zn, C
At least one of d, Mg and Be can be added.

If the nitride semiconductor underlayer is a GaN film,
It is preferable in the following points. That is, since the GaN film is a binary mixed crystal, the controllability of crystal growth is good. Further, since the surface migration length of the GaN film is longer than that of the AlGaN film and shorter than that of the InGaN film, appropriate lateral growth can be obtained so as to completely and flatly cover the grooves and hills. The impurity concentration added to the GaN film used as the nitride semiconductor underlayer is 1 × 10 ^{17 to} 8 × 1
It is preferably within the range of 0 ¹⁸ / cm ³ . By adding impurities in such a concentration range, the surface morphology of the nitride semiconductor underlayer is improved, the thickness of the light emitting layer is made uniform, and the laser device characteristics can be improved.

If the nitride semiconductor underlayer is an AlGaN film, it is preferable in the following points. Since the AlGaN film contains Al, the surface migration length is shorter than that of the GaN film or the InGaN film. The fact that the surface migration length is short means that the nitride semiconductor film is not easily deposited on the bottom of the groove while the inside of the groove is laterally covered with the nitride semiconductor film. That is, AlGa
In the N film, the crystal growth is promoted from the side wall of the groove, and the lateral growth becomes remarkable, so that the crystal distortion can be further alleviated. Al _x
The Al composition ratio x of the Ga _1-x N film is 0.01 or more and 0.1
5 or less, preferably 0.01 or more and 0.07 or less.
It is more preferred that: When the composition ratio x of Al is 0.
If it is smaller than 01, the above-mentioned surface migration length may be increased. On the other hand, if the composition ratio x of Al is larger than 0.15, the surface migration length becomes too short, and the groove may not be buried flat. The effect similar to that of the AlGaN film is obtained as long as the nitride semiconductor underlayer contains Al. AlG used as a nitride semiconductor underlayer
The impurity concentration added to the aN film is 3 × 10 ^{17 to} 8 × 10
It is preferably in the range of ¹⁸ / cm ³ . By the addition of the impurities in such a concentration range, the surface migration length of the nitride semiconductor underlayer is shortened, and the crystal distortion can be further reduced.

If the nitride semiconductor underlayer is an InGaN film, it is preferable in the following points. Since the InGaN film contains In, it is more elastic than the GaN film or the AlGaN film. Therefore, the InGaN film is buried in the groove of the processed substrate and diffuses crystal strain from the substrate throughout the nitride semiconductor film, thereby reducing local crystal strain and suppressing cracks. The In composition ratio x of the In _x Ga ₁ -xN film is preferably 0.01 or more and 0.18 or less, and more preferably 0.01 or more and 0.1 or less. If the composition ratio x of In is smaller than 0.01, the effect of the elastic force due to the inclusion of In may not be easily obtained. The composition ratio x of In is 0.18.
If it is larger than that, the crystallinity of the InGaN film may be reduced. Note that the same effects as those of the InGaN film can be obtained as long as the nitride semiconductor underlayer contains In. The impurity concentration added to the InGaN film used as the nitride semiconductor underlayer is 1 × 10 ¹⁷
It is preferably in the range of ５5 × 10 ¹⁸ / cm ³ .
The addition of the impurity in such a concentration range is preferable because the surface morphology of the nitride semiconductor underlayer can be improved and the elasticity can be maintained.

(About the thickness of the nitride semiconductor underlayer)

In order for the processed substrate to be completely covered with the nitride semiconductor underlayer, the underlayer must be sufficiently thick. On the other hand, in order that the processed substrate is not completely covered with the nitride semiconductor underlayer, the underlayer must be thin. In order to solve the problem of the present invention, the processed substrate does not have to be completely covered with the nitride semiconductor underlayer. However, from the viewpoint of the yield of the laser element chip, it is preferable to completely cover the processed substrate with the nitride semiconductor underlayer. Therefore, it is preferable that the thickness of the nitride semiconductor underlayer is approximately 2 μm or more and 20 μm or less. If the coating film thickness is less than 2 μm, it may be difficult to completely and flatly bury the groove with the nitride semiconductor film, depending on the groove width and groove depth formed in the processed substrate. On the other hand, if the coating thickness is greater than 20 μm,
The growth in the vertical direction (perpendicular to the main surface of the substrate) becomes more and more remarkable than the lateral growth on the processed substrate, and the effect of alleviating crystal distortion and the effect of suppressing cracks are not sufficiently exhibited.

[Embodiment 2]

As a second embodiment, a method of manufacturing a coated substrate according to the present invention will be described with reference to FIG. Note that items not specifically mentioned in the present embodiment are the same as those in the first embodiment.

(Production method of coated substrate)

FIG. 3 is a schematic cross-sectional view showing a coated substrate in which a nitride semiconductor base layer is coated on a processed substrate. The processed substrate can be manufactured as follows. First, a stripe-shaped mask pattern was formed on the surface of an n-type GaN substrate having a (0001) principal plane orientation by using a lithography technique. A groove was formed in the n-type GaN substrate along the mask pattern by a dry etching method. The grooves and hills formed in this way are n-type GaN
Along the <1-100> direction of the substrate, hill width 15μ
m, a groove depth of 2.2 μm, and a groove width of 12 μm.

The processed substrate thus produced is sufficiently organically cleaned and then carried into an MOCVD (metal organic chemical vapor deposition) apparatus, where an underlayer made of an Al _0.05 Ga _0.95 N film having a coating thickness of 6 μm is laminated. Was. In the formation of the Al _0.05 Ga _0.95 N underlayer, NH ₃ (ammonia), which is a raw material for group V elements, and II are used on a processing substrate set in a MOCVD apparatus.
TMGa (trimethylgallium) and TMAl (trimethylaluminum) as raw materials for group I elements are supplied, and
At a crystal growth temperature of 050 ° C.,
H ₄ (Si impurity concentration 1 × 10 ¹⁸ / cm ³ ) was added.

In this embodiment, the groove forming method by the dry etching method is described as an example, but it goes without saying that other groove forming methods may be used. For example, wet etching, scribing, wire sawing,
Electric discharge machining, sputtering, laser machining, sandblasting, focus ion beam machining, and the like can be used.

In the present embodiment, the n-type GaN substrate <1-
A groove was formed along the <100> direction.
A groove may be formed along the direction.

In the present embodiment, (0001)
Although a GaN substrate having a plane is used, other plane orientations and other nitride semiconductor substrates may be used. Regarding the plane orientation of the nitride semiconductor substrate, the C plane {0001},
A plane {11-20}, R plane {1-102}, M plane {1-
The {100} and {1-101} planes can be preferably used. In addition, a substrate having a main surface having an off angle of 2 degrees or less from these plane orientations has good surface morphology.

(Crystal Growth)

FIG. 1 shows a nitride semiconductor laser device formed using a coated substrate. The nitride semiconductor laser device shown in FIG. 1 has a coated substrate 100 composed of a processed substrate (n-type GaN substrate) 101 and an n-type Al _0.05 Ga _0.95 N underlayer 102, an n-type In _0.07 Ga _0.93 N crack prevention layer. 103, n-type Al _0.1 Ga _0.9 N clad layer 1
04, n-type GaN light guide layer 105, light emitting layer 106, p
Type Al _0.2 Ga _0.8 N carrier block layer 107, p-type G
aN optical guide layer 108, p-type Al _0.1 Ga _0.9 N cladding layer 109, p-type GaN contact layer 110, n-electrode 11
1, including a p-electrode 112 and a SiO ₂ dielectric film 113.

On the coated substrate 100, in a MOCVD apparatus, NH _{3 as a} group V element material and TMGa or TEGa (triethyl gallium) as a group III element material are added to a group III element material TMIn (trimethyl indium). ) And SiH ₄ as an impurity,
At a crystal growth temperature of 0 ° C., an n-type In _0.07 Ga _0.93 N crack preventing layer 103 was grown to a thickness of 40 nm. next,
The substrate temperature is raised to 1050 ° C and the raw material for group III element TMAl or TEAl (triethylaluminum)
Is used, and a 1.2 μm thick n-type Al _0.1 Ga _0.9 N
Cladding layer 104 (Si impurity concentration 1 × 10 ¹⁸ / c
m ³ ) is grown, followed by the n-type GaN light guide layer 1
05 (Si impurity concentration 1 × 10 ¹⁸ / cm ³ ) has a thickness of 0.
It was grown to 1 μm.

Thereafter, the substrate temperature is lowered to 800 ° C.
A light emitting layer (multiple quantum well structure) 106 in which an In _0.01 Ga _0.99 N barrier layer having a thickness of 8 nm and an In _0.15 Ga _0.85 N well layer having a thickness of 4 nm were alternately laminated was formed. In this embodiment, the light emitting layer 106 has a multiple quantum well structure starting at the barrier layer and ending at the barrier layer, and includes three (three periods) quantum well layers. In addition, S is added to both the barrier layer and the well layer.
i impurity was added at a concentration of 1 × 10 ¹⁸ / cm ³ . Note that a crystal growth interruption period of 1 second or more and 180 seconds or less may be inserted between the barrier layer and the well layer or between the well layer and the barrier layer. This is preferable because the flatness of each layer is improved and the half width of the emission spectrum is reduced.

When As is added to the light emitting layer 106, AsH ₃ or TBAs (tert-butylarsine) is used.
And when P is added, PH ₃ (phosphine)
Or using TBP (tertiary butyl phosphine)
When Sb is added, TMSb (trimethylantimony) or TESb (triethylantimony)
May be used. Further, when the light emitting layer is formed, dimethylhydrazine may be used as the N raw material in addition to NH ₃ .

Next, the temperature of the substrate is raised again to 1050 ° C., and a p-type Al _0.2 Ga _0.8 N carrier block layer 107 having a thickness of 20 nm, a p-type GaN optical guide layer 108 having a thickness of 0.1 μm, and a A 0.5 μm p-type Al _0.1 Ga _0.9 N cladding layer 109 and a 0.1 μm thick p-type GaN contact layer 110 were sequentially grown. As the p-type impurity, Mg (EtCP ₂ Mg: bisethylcyclopentadienyl magnesium) is 5 × 10 ¹⁹ / cm ³ to 2 × 1.
It was added at a concentration of 0 ²⁰ / cm ³ . It is preferable that the p-type impurity concentration of p-type GaN contact layer 110 be increased as approaching the interface with p-electrode 112. By doing so, the contact resistance at the interface with the p-electrode is reduced. Further, a small amount of oxygen may be mixed during the growth of the p-type layer in order to remove residual hydrogen in the p-type layer which is preventing activation of Mg which is a p-type impurity.

After the p-type GaN contact layer 110 is thus grown, all the gases in the reactor of the MOCVD apparatus are changed to nitrogen carrier gas and NH ₃ ,
The substrate temperature was cooled at a cooling rate of 0 ° C./min. When the substrate temperature was cooled to 800 ° C., the supply of NH ₃ was stopped, the substrate temperature was maintained for 5 minutes, and then cooled to room temperature. The holding temperature of this substrate is from 650 ° C. to 900
° C, and the holding time is 3 minutes or more and 1 hour.
Preferably, it was less than 0 minutes. Further, the cooling rate to room temperature is preferably 30 ° C./min or more. The crystal growth film thus formed was evaluated by Raman measurement. As a result, even if the conventional p-type annealing was not performed, the growth film had already exhibited p-type characteristics (that is, Mg was activated). Had been turned). Also, the p electrode 112
The contact resistance at the time of forming was also reduced. In addition to this, if conventional p-type annealing is combined, Mg
The activation rate was further improved, which was favorable.

In the crystal growth step according to the present embodiment, the crystal may be continuously grown from the processed substrate to the nitride semiconductor laser layer, or the growth step from the processed substrate to the coated substrate may be performed in advance. Regrowth for growing the nitride semiconductor laser layer may be performed later.

In the embodiment, the In _0.07 Ga _0.93 N crack preventing layer 103 may have an In composition ratio other than 0.07, or the InGaN crack preventing layer may be omitted. However, when lattice mismatch between the cladding layer and the GaN substrate becomes large, it is preferable to insert an InGaN crack prevention layer.

Although the light emitting layer 106 of this embodiment starts with a barrier layer and ends with a barrier layer, the light emitting layer 106 may start with a well layer and end with a well layer. Further, the number of well layers in the light emitting layer is not limited to the above-mentioned three layers, and if the number of well layers is ten or less, the threshold current density becomes low, and continuous oscillation at room temperature was possible. In particular, when the number of well layers is 2 or more and 6 or less, the threshold current density is lowered, which is preferable.

In the light emitting layer 106 of this embodiment, Si is added to both the well layer and the barrier layer at a concentration of 1 × 10 ¹⁸ / cm ³ , but Si may not be added. However, the emission intensity was higher when Si was added to the light emitting layer. The impurity added to the light emitting layer is not limited to Si, and at least one of O, C, Ge, Zn, and Mg may be added. The total amount of impurities added was preferably about 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ . Further, the layer to which the impurity is added is not limited to both the well layer and the barrier layer, and the impurity may be added to only one of these layers.

The p-type Al _0.2 Ga _0.8 N carrier block layer 107 of the present embodiment may have an Al composition ratio other than 0.2 or may omit this carrier block layer. However, the threshold current density was lower when the carrier block layer was provided. This is because the carrier block layer 107 has a function of confining carriers in the light emitting layer 106. It is preferable to increase the Al composition ratio of the carrier block layer because this increases the confinement of carriers. Conversely, it is preferable to reduce the Al composition ratio within a range in which the confinement of carriers is maintained, because the carrier mobility in the carrier block layer increases and the electric resistance decreases.

In this embodiment, the p-type cladding layer 109 and
Al as the n-type cladding layer 104 _0.1Ga_0.9N crystal
Although it was used, even if its Al composition ratio was other than 0.1
Good. If the mixed crystal ratio of Al increases,
The energy gap difference and the refractive index difference increase,
And light are efficiently confined in the light emitting layer, and the laser oscillation threshold
Value current density can be reduced. Conversely, carriers and light
Reduce the Al composition ratio within the range where confinement is maintained
If the carrier mobility in the cladding layer increases,
The operating voltage of the child can be reduced.

The thickness of the AlGaN cladding layer is 0.7 μm
It is preferably within a range of about 1.5 μm, which makes the vertical and transverse modes unimodal and increases the optical confinement efficiency, thereby improving the optical characteristics of the laser and reducing the laser threshold current density.

The cladding layer is not limited to a ternary mixed crystal of AlGaN, but may be a quaternary mixed crystal of AlInGaN, AlGaNP, AlGaNAs or the like. Further, the p-type cladding layer has a p-type AlGaN layer and a p-type
It may have a superlattice structure including a p-type GaN layer or a superlattice structure including a p-type AlGaN layer and a p-type InGaN layer.

In this embodiment, the crystal growth method using the MOCVD apparatus has been described as an example, but the molecular beam epitaxy method (MB
E), hydride vapor phase epitaxy (HVPE) or the like may be used.

(Chip-forming step)

The epi-wafer formed by the above-described crystal growth is taken out of the MOCVD apparatus and processed into a laser device. Here, the surface of the epiwafer on which the nitride semiconductor laser layer was formed was flat, and the grooves and hills formed on the processed substrate were completely buried in the nitride semiconductor base layer and the light emitting element structure layer.

Since the coated substrate 100 is an n-type conductive nitride semiconductor, an n-electrode 111 is formed on the back surface side in the order of Hf / Al (see FIG. 1). As the n-electrode, a stack of Ti / Al, Ti / Mo, or Hf / Au may be used. It is preferable to use Hf for the n-electrode because the contact resistance is reduced.

The p-electrode portion was etched in a stripe shape along the groove direction of the processing substrate 101, thereby forming a ridge stripe portion (see FIG. 1). The ridge stripe part is formed at a position 4 μm away from the center of the hill,
It had a width of 1.6 μm. Thereafter, a SiO ₂ dielectric film 113 is deposited, the upper surface of the p-type GaN contact layer 110 is exposed from the dielectric film, and the p-electrode 1 is formed thereon.
12 was deposited and formed as a Pd / Mo / Au stack. Pd / Pt / Au, Pd / A
u, or a stack of Ni / Au or the like may be used.

Finally, the epi-wafer is cleaved in a direction perpendicular to the longitudinal direction of the ridge stripe, and a resonator length of 50
A 0 μm Fabry-Perot resonator was fabricated. The resonator length is generally preferably in the range of 300 μm to 1000 μm. The M-plane {1-100} of the nitride semiconductor crystal is an end face of a mirror end face having a cavity length in which a groove is formed along the <1-100> direction.

The feedback method of the laser resonator is as follows.
Commonly known DFB (distributed feedback), DBR (distributed Bragg reflection) and the like can also be used.

After the mirror end face of the Fabry-Perot resonator is formed, dielectric films of SiO ₂ and TiO ₂ are alternately deposited on the mirror end face to form a dielectric multilayer reflective film having a reflectance of 70%. Been formed. As the dielectric multilayer reflective film, a multilayer film such as SiO ₂ / Al ₂ O ₃ can be used.

Note that the n-electrode 111 is
Formed on the back surface of the n-type Al _0.05 Ga _0.95 N film 102 from the front side of the epi-wafer using a dry etching method.
May be exposed, and an n-electrode may be formed in the exposed region.

(Package mounting)

The obtained semiconductor laser device chip is mounted on a package. When using a high-power nitride semiconductor laser device, attention must be paid to measures for heat radiation. It is preferable that the high-power nitride semiconductor laser device is connected by using an In solder material with the semiconductor junction on the lower side. The high-power nitride semiconductor laser device can be directly attached to the package body or the heat sink.
i, AlN, diamond, Mo, CuW, BN, F
The connection may be made via a submount of e, Cu, SiC, or Au.

As described above, the nitride semiconductor laser device according to the present embodiment is manufactured.

In this embodiment, the GaN processing substrate 1 is used.
Although 01 was used, a processed substrate of another nitride semiconductor may be used. For example, in the case of a nitride semiconductor laser, it is preferable that a layer having a lower refractive index than the cladding layer is in contact with the outside of the cladding layer in order to make the vertical and transverse modes unimodal, and an AlGaN substrate can be preferably used. .

[Embodiment 3]

In the third embodiment, a nitride semiconductor laser device having a current blocking layer instead of the ridge stripe structure (see FIG. 4) was manufactured. Note that items not specifically mentioned in the present embodiment are described in the first embodiment.
And 2 are the same.

Hereinafter, the laser device having the current blocking layer according to the present embodiment will be described in more detail with reference to FIG. The laser device shown in FIG. 8 includes a coated substrate 100, an n-type In _0.07 Ga _0.93 N crack prevention layer 10.
3, n-type Al _0.1 Ga _0.9 N cladding layer 104, n-type Ga
N light guide layer 105, light emitting layer 106, p-type Al _0.2 Ga
_0.8 N carrier block layer 107, p-type GaN light guide layer 108, first p-type Al _0.1 Ga _0.9 N cladding layer 109
a, the current blocking layer 120 includes a 2p-type Al _0.1 Ga _{0 .9} N cladding layer 109b, p-type GaN contact layer 110, n electrode 111, and a p-electrode 112.

The current blocking layer 120 may be a layer capable of narrowing the current so that the current injected from the p-type electrode 112 passes only through the current blocking interlayer width in FIG. For example,
An n-type Al _0.25 Ga _0.75 N layer can be used as the current blocking layer 120, and the composition ratio of Al is not limited to 0.25 and may be another composition ratio.

In the laser device of this embodiment, the hill width is 12 μm, the groove width is 18 μm, and the groove depth is 1.7.
μm, and the current blocking interlayer width was set to 1.8 μm. The width of the current blocking layer was formed at a distance of 3 μm from the center of the hill.

[Embodiment 4]

In the fourth embodiment, the grooves and hills described in the second embodiment are formed on a nitride semiconductor modified substrate including a nitride semiconductor basic substrate and a nitride semiconductor layer laminated thereon. Other than the above, it is the same as the first and second embodiments.

In the method of manufacturing a coated substrate according to this embodiment, first, n-type GaN having a (0001) principal plane orientation is used.
A base substrate was loaded into the MOCVD apparatus. Its n-type G
NH ₃ and TMGa were supplied on the aN base substrate, and a low-temperature GaN buffer layer was formed at a relatively low growth temperature of 550 ° C. Then, the growth temperature is raised to 1050 ° C., and NH ₃ , TMGa,
And SiH ₄ were supplied, and an n-type GaN layer was stacked. The nitride semiconductor repair substrate on which the n-type GaN layer was laminated was taken out of the MOCVD apparatus. A striped mask pattern was formed on the surface of the n-type GaN layer of the modified substrate taken out of the MOCVD apparatus by using lithography technology. Then, a groove was formed along the mask pattern by dry etching, and thus a processed substrate was completed. Here, the grooves and hills formed on the processed substrate were formed along the <1-100> direction of the n-type GaN modified substrate with dimensions of a hill width of 25 μm, a groove depth of 3 μm, and a groove width of 10 μm.

The processed substrate is sufficiently organically cleaned, and
The n-type G having a coating film thickness of 5 μm is transported again into the CVD apparatus.
An aN underlayer was laminated. Thus, the coated substrate according to the fourth embodiment was completed.

The low-temperature GaN buffer layer described in the present embodiment may be a low-temperature Al _x Ga ₁ -xN (0 ≦ x ≦ 1) buffer layer, or the low-temperature buffer layer itself may be omitted. Is also good. However, the currently supplied GaN substrate has a low surface morphology because the surface morphology is not sufficiently favorable.
It is preferable to insert the l _x Ga _1-x N buffer layer because the surface morphology is improved. Note that the low-temperature buffer layer means a buffer layer formed at a relatively low growth temperature of about 450 to 600 ° C. The buffer layer formed in this growth temperature range is polycrystalline or amorphous.

[Embodiment 5]

The fifth embodiment is the same as the above-described embodiment except that the light-emitting layer contains at least one of As, P, and Sb to be replaced with a part of N. . More specifically, As, P, and Sb
Was substituted for at least a part of N of the well layer in the light emitting layer of the nitride semiconductor laser device. At this time, As contained in the well layer,
When the composition ratio of the total of P and / or Sb is x and the composition ratio of N is y, x is smaller than y and x /
(X + y) is 0.3 (30%) or less, and preferably 0.2 (20%) or less. The lower limit of the preferred concentration of the sum of As, P, and / or Sb is 1 ×
It was 10 ¹⁸ / cm ³ or more.

The reason is that the substitution element composition ratio x is 20%
If the composition ratio x becomes higher than 30%, a hexagonal system and a cubic system coexist from the concentration separation when the composition ratio x becomes higher than 30%. This is because the crystal system of the well layer starts to decrease due to the shift to the crystalline separation. On the other hand, if the total concentration of the substitution elements is less than 1 × 10 ¹⁸ / cm ³ , the effect of including the substitution elements in the well layer becomes difficult to obtain.

The effect of the present embodiment is that the effective mass of electrons and holes in the well layer is reduced and the mobility is reduced by including at least one of As, P and Sb in the well layer. growing. In the case of a semiconductor laser device, a small effective mass means that a carrier inversion distribution for laser oscillation can be obtained with a small current injection amount, and a large mobility means that electrons and holes disappear in the light emitting layer due to radiative recombination. This also means that new electrons and holes can be injected at high speed by diffusion. That is,
Compared to an InGaN-based nitride semiconductor laser device in which the light-emitting layer does not contain any of As, P, and Sb, in the present embodiment, the threshold current density is lower and the self-sustained pulsation characteristics are excellent (excellent noise characteristics). Further, a semiconductor laser can be obtained.

[Sixth Embodiment]

In the sixth embodiment, the nitride semiconductor laser device according to the above-described embodiment is applied to an optical device. Blue-violet (350-420n) according to the above-described embodiment
The nitride semiconductor laser element having an oscillation wavelength of m) can be preferably used in various optical devices. For example, when it is used in an optical pickup device, it is preferable in the following points. That is, since such a nitride semiconductor laser device has a low threshold current density and can operate stably with high output even in a high-temperature atmosphere, it is most suitable for a highly reliable optical disk device for high-density recording and reproduction ( The shorter the oscillation wavelength, the higher the density of recording / reproduction is possible).

FIG. 9 is a schematic block diagram showing an optical disk device including an optical pickup such as a DVD device as an example in which the nitride semiconductor laser device according to the above-described embodiment is used in an optical device. .
In this optical information recording / reproducing apparatus, a laser beam 3 emitted from a nitride semiconductor laser element 1 is modulated by an optical modulator 4 according to input information, and is recorded on a disk 7 via a scanning mirror 5 and a lens 6. You. The disk 7 is rotated by a motor 8. At the time of reproduction, the reflected laser light optically modulated by the pit arrangement on the disk 7 is detected by the detector 10 via the beam splitter 9,
As a result, a reproduced signal is obtained. The operation of each of these elements is controlled by the control circuit 11. Laser element 1
Is usually 30 mW during recording and about 5 mW during reproduction.

The laser element according to the present invention can be used not only in the above-mentioned optical disk recording / reproducing apparatus but also in a laser printer, a bar code reader, a projector using three primary colors of light (blue, green, and red) lasers. I can do it.

[0111]

As described above, according to the present invention, the threshold current density can be improved in the nitride semiconductor laser device.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a nitride semiconductor laser device formed above using a coated substrate of the present invention.

FIG. 2A is a schematic cross-sectional view showing one example of a nitride semiconductor processed substrate that can be used in the present invention;
(B) shows the top view.

FIG. 3 is a schematic sectional view showing an example of a coated substrate that can be used in the present invention.

4A is a schematic cross-sectional view illustrating an example of a nitride semiconductor laser device having a ridge stripe structure, and FIG. 4B is a schematic diagram illustrating an example of a nitride semiconductor laser device having a current blocking layer structure. FIG.

FIG. 5 is a diagram showing a relationship between a formation position of a ridge stripe portion of a nitride semiconductor laser device formed on a coated substrate that can be used in the present invention and a laser oscillation threshold current density.

FIG. 6 is a schematic cross-sectional view showing a preferred formation region of a current confinement structure formed on a coated substrate that can be used in the present invention.

FIG. 7 is a graph showing a relationship between a groove depth of a processing substrate and a reduction rate of a laser oscillation threshold current density.

FIG. 8 is a sectional view showing an example of a nitride semiconductor laser device having a current blocking layer according to the present invention.

FIG. 9 is a schematic block diagram showing an example of an optical device including an optical pickup device using a nitride semiconductor laser device according to the present invention.

[Explanation of symbols]

100 coated substrate, 101 processed substrate, 102 n
_-Type Al _0.05 Ga _0.95 N film, 103 n-type In _0.07 Ga
_0.93 N crack preventing layer, 104 n-type Al _0.1 Ga _0.9 N
Clad layer, 105 n-type GaN light guide layer, 106
Light-emitting layer, 107 p-type Al _0.2 Ga _0.8 N carrier block layer, 108 p-type GaN guide layer, 109, 109a,
p-type Al _0.1 Ga _0.9 N cladding layer, 110 p-type Ga
N contact layer, 111 n electrode, 112 p electrode, 1
13 SiO ₂ dielectric film, 120 Current blocking layer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinya Ishida 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Daisuke Hanaoka 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Incorporated (72) Inventor Tsuyoshi Kamikawa Sharp Corporation 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Prefecture (72) Inventor Susumu Omi 22-22 Nagaikecho Naganocho, Abeno-ku, Osaka City, Osaka F Terms (reference) 5D119 AA11 AA22 BA01 EB02 FA05 FA17 5F045 AA04 AB17 AB18 AC08 AC12 AD14 AF09 AF11 BB11 BB16 CA12 DA55 5F073 AA13 AA74 BA05 BA06 CA07 CB02 CB19 CB22 DA05 DA32 EA23

Claims (13)

[Claims] A processing substrate including a groove and a hill formed on one main surface of the nitride semiconductor substrate; a nitride semiconductor underlayer covering the groove and the hill of the processing substrate; And a nitride semiconductor multilayer light emitting structure including a quantum well layer or a quantum well layer and a light emitting layer including a barrier layer in contact with the quantum well layer between the n-type layer and the p-type layer. A nitride semiconductor laser device wherein a current confinement portion of the light emitting structure is formed above a region separated by a distance and within a width of the hill. 2. The nitride semiconductor laser device according to claim 1, wherein the width of the hill is in a range of 4 to 30 μm. 3. The nitride semiconductor laser device according to claim 1, wherein the width of the groove is in a range of 2 to 30 μm. 4. A longitudinal direction of the groove or a longitudinal direction of the hill is a <1-100> direction or <11> direction of a crystal of the substrate.
The nitride semiconductor laser device according to claim 1, wherein the nitride semiconductor laser device is substantially parallel to a −20> direction. 5. The nitride semiconductor laser device according to claim 1, wherein the width of the hill is wider than the width of the groove. 6. The nitride semiconductor laser device according to claim 1, wherein a depth of said groove is in a range of 0.25 to 10 μm. 7. The nitride semiconductor underlayer comprises Si, O,
1 × 10 ¹⁷ -8 × 10 10
^{2. The} composition according to claim 1, wherein the concentration is within the range of ¹⁸ / cm ^3.
7. The nitride semiconductor laser device according to any one of items 6 to 6. 8. The nitride semiconductor underlayer is made of Al _x Ga _{1 -x.}
7. The nitride semiconductor laser device according to claim 1, comprising N (0.01 ≦ x ≦ 0.15). 9. The Al _x Ga ₁ -xN (0.01 ≦ x ≦
0.15) is Si, O, Cl, S, C, Ge, Zn, C
9. The nitride semiconductor laser device according to claim 8, wherein at least one of d, Mg, and Be is contained as an impurity in a range of ³ × 10 ^{17 to} 8 × 10 ¹⁸ / cm ³ . 10. The nitride semiconductor underlayer is made of In _x Ga.
7. The nitride semiconductor laser device according to claim 1, comprising _1-x N (0.01.ltoreq.x.ltoreq.0.18). 11. The In _x Ga ₁ -xN (0.01 ≦ x ≦
0.18) is Si, O, Cl, S, C, Ge, Zn, C
11. The nitride semiconductor laser device according to claim 10, wherein at least one of d, Mg, and Be is contained as an impurity within a range of 1 × 10 ^{17 to} 5 × 10 ¹⁸ / cm ³ . 12. The quantum well layer comprises As, P, and S
The nitride semiconductor laser device according to claim 1, wherein the nitride semiconductor laser device includes at least one of b. 13. An optical device comprising the nitride semiconductor laser device according to claim 1. Description: