JP3218595B2 - Nitride semiconductor laser device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nitride semiconductor (In).
_{X Al Y Ga 1-XY N} , 0 ≦ X, 0 ≦ Y, the laser device and its manufacturing method consisting of X + Y ≦ 1).

[0002]

2. Description of the Related Art A nitride semiconductor is known as a material for a laser device that emits light in the ultraviolet to blue region, and the present applicant has recently used this material to generate a laser oscillation of 410 nm at room temperature under pulse current. Announced (for example, Jpn.J.
Appl. Phys. Vol 35 (1996) pp. L74-76). The disclosed laser device is a so-called electrode stripe type laser device, in which the stripe width of the nitride semiconductor layer including the active layer is set to several tens of μm, and laser oscillation is performed. However, the laser device still only performs pulse oscillation, and has a threshold current of 1 to 2 A. For continuous oscillation, the threshold current needs to be further reduced.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel laser device made of a nitride semiconductor and a method of manufacturing the same, thereby lowering the threshold current of the laser device. The goal is to achieve continuous oscillation.

[0004]

Means for Solving the Problems A nitride semiconductor laser device of the present invention has at least an n-type nitride semiconductor layer on a substrate and a stripe formed by exposing the n-type nitride semiconductor layer by etching. In a double-heterostructure nitride semiconductor laser device having a p-type nitride semiconductor layer and a p-type nitride semiconductor layer in that order, the n-type nitride is located on both sides of the stripe of the active layer more than the uppermost layer of the active layer. A current composed of i-type In _x Al _y Ga _1-xy N (y ≧ 0.4) having a thickness of 0.5 μm or less on the surface of the n-type nitride semiconductor layer exposed by etching in a range close to the semiconductor side. A blocking layer is formed, and a p-type nitride semiconductor layer is formed in contact with both side surfaces of the stripe of the active layer.

Another aspect of the laser device of the present invention is that
A second p-type nitride semiconductor layer having a stripe identical to the stripe of the active layer and having a larger band gap than the active layer is formed between the active nitride layer and the active nitride layer. And

[0006]

Further, a method for manufacturing a laser device according to the present invention
A first step of sequentially growing at least an n-type nitride semiconductor layer and an active layer on the substrate, and after the first step, the active layer is etched in a stripe shape and a surface of the n-type nitride semiconductor layer is formed. And a third step of growing a current blocking layer on the n-type nitride semiconductor layer in a range closer to the n-type nitride semiconductor layer side than the uppermost layer of the active layer after the second step. And a fourth step of, after the third step, growing a p-type nitride semiconductor layer on the current blocking layer so as to be in contact with the stripe side surface of the active layer.

[0008]

FIG. 1 is a schematic sectional view showing the structure of a laser device according to one embodiment of the present invention. The basic structure is such that an n-type contact layer 2, an n-type cladding layer 3, a current blocking layer 20, an active layer 4, a p-type cladding layer 5, and a p-type contact layer 6 are laminated on a substrate 1. And the active layer 4 has a shape having a stripe-shaped waveguide region. 10 is formed on the surface of the n-type contact layer 2 and is a striped n-electrode formed symmetrically with respect to the active layer. 11 is formed on the surface of the p-type contact layer 6 and located at the stripe position of the active layer. It is a striped p-electrode formed correspondingly.

The substrate 1 includes sapphire having a plane orientation such as A-plane, C-plane and R-plane, and spinel (MgAl ₂ O ₄ ) 1
A known substrate made of a single crystal of eleven surfaces, such as SiC, MgO, Si, ZnO, and GaN, is used.

The n-type contact layer 2 is a layer on which an n-electrode 10 is formed and into which a current is injected.
n _X Al _Y Ga _1-XY N (0 ≦ X, 0 ≦ Y, X + Y ≦ 1), and particularly, Al _Y Ga _1-Y N (0 ≦ Y <1)
Is preferred. When GaN is used, an n-type layer having a high carrier concentration is obtained, and particularly preferable ohmic contact with the n-electrode is obtained. AlGaN can act as a cladding layer as a light confinement layer because the refractive index difference with the active layer can be increased. In other words, if the contact layer is made of AlGaN, it acts not only as a layer for injecting current but also as a layer for confining light in the active layer. In the case of GaN, the ohmic characteristics with the n-electrode are very excellent,
Since the difference in the refractive index from the active layer is small, the laser beam tends to spread in the GaN layer, and tends to hinder the lowering of the threshold value.
By using AlGaN, the light emission of the active layer can be hardly spread in the contact layer, so that the threshold value decreases. It is desirable that the thickness of the n-type contact layer 2 is adjusted to 0.1 μm or more and 5 μm or less. If the thickness is less than 0.1 μm, it is disadvantageous because when the electrodes are provided on the same surface side, precise control of the etching rate is required. If the thickness is more than 5 μm, cracks tend to be easily formed in the crystal. Note that an n-type nitride semiconductor has the property of becoming n-type due to nitrogen vacancies formed inside the crystal even when non-doped (in a state where impurities are not doped), but donor impurities such as Si, Ge, and Sn are grown during crystal growth. By doing so, a nitride semiconductor having a high carrier concentration and exhibiting preferable n-type characteristics can be obtained. Further, in order to reduce lattice mismatch between the substrate and the nitride semiconductor, a Ga having a thickness of 10 Å to 0.1 μm or less is provided between the substrate 1 and the n-type contact layer 2.
A buffer layer made of N, AlN, AlGaN, or the like may be formed. In addition, Al, Ti,
Metals or alloys such as W, Cu, Zn, Sn, and In can provide an ohmic.

The n-type cladding layer 3 functions as a light confinement layer of the active layer, and is made of a nitride semiconductor having a larger band gap than the active layer, preferably an n-type nitride semiconductor containing Al. More preferably, a binary or ternary mixed crystal of Al _{Y ′} Ga _{1-Y ′} N (0 <Y ′ ≦ 1) is obtained, whereby a crystal having good crystallinity can be obtained, and refraction with the active layer can be obtained. It is effective for confining the longitudinal mode of the laser beam by increasing the rate difference. This layer is usually preferably grown to a thickness of 0.1 μm to 1 μm. The n-type contact layer 2 is made of AlG
In the case of using aN, the n-type cladding layer 3 can be omitted.

The next current blocking layer 20 is the most characteristic feature of the present invention. On both sides of the stripe of the active layer 4, an area closer to the n-type nitride semiconductor side than the uppermost layer of the active layer 4 is formed. , On the n-type nitride semiconductor layer.
In FIG. 1, the n-type nitride semiconductor corresponds to the n-type cladding layer 3. The current blocking layer 20 functions to constrict the current on the n-layer side and concentrate the current on the active layer 4. More importantly, the range in which the current blocking layer 20 is closer to the n-type cladding layer 3 than the top layer of the active layer 4, that is, the top layer of the current blocking layer 20 is the p-type cladding layer 5 and the active layer 4 Is formed at a film thickness in a range at a position on the n-layer side from the interface with the substrate. By forming with such a film thickness, the p-type cladding layer 5 having a larger band gap than the active layer goes around the stripe side surface of the active layer 4,
Acts as a lateral mode light confinement layer. Therefore, the uppermost layer of the current blocking layer 20 needs to be on the n-layer side from the interface between the active layer 4 and the p-type cladding layer 5, that is, the uppermost layer of the active layer needs to be located at a lower position. The uppermost layer of the current blocking layer 20 is located at a position equal to or less than half the thickness of the active layer, and more preferably, as shown in FIG.
It is desirable that the side surface of the stripe-shaped active layer is buried with the p-type cladding layer 4 on the n-type layer side of the interface between the active layer and the n-type cladding layer 3.

The current blocking layer 20 needs to have a structure capable of growing a nitride semiconductor on the current blocking layer and blocking current. Therefore, it is most preferable that the current blocking layer be formed of an i (insulator) type nitride semiconductor. In addition, the current blocking layer may be a multilayer film of a nitride semiconductor having an inverted np junction. When the current blocking layer is an i-type nitride semiconductor,
The nitride semiconductor has an In _x Al _Y Ga _{1 -XYN} composition and an Al mixed crystal ratio, that is, a Y value of 0.4 or more, and more preferably 0.5 or more. It is easy to be. More preferably, doping during growth with a p-type impurity tends to make it more easily i-type. When growing an i-type nitride semiconductor having a high Al mixed crystal ratio, the film thickness is adjusted to 0.5 μm or less, more preferably 0.1 μm or less. This is because if the thickness is larger than 0.5 μm, cracks are easily formed in the crystal.

The active layer 4 has a multiple quantum well structure in which at least a well layer contains a nitride semiconductor containing In. The multiple quantum well structure is a structure in which a well layer and a barrier layer are stacked. In the case of the present invention, if the well layer is made of a nitride semiconductor containing In, the barrier layer has a band gap greater than that of the well layer. If In is large, it is not particularly necessary to include In. Preferably, a well layer made of In _x Ga ₁ -xN (0 <x ≦ 1);
A structure in which barrier layers made of In _{X ′} Ga _{1−X ′} N (0 ≦ X ′ <1, X ′ <X) are stacked. Since ternary mixed crystal InGaN can be obtained with better crystallinity than quaternary mixed crystal,
Light emission output is improved. Further, the barrier layer has a band gap energy larger than that of the well layer, and the well layer + the barrier layer + the well layer +
.., A barrier and a well layer (or vice versa) are stacked to form a multiple quantum well structure. If the active layer is MQW in which InGaN is stacked as described above, a high-power LD between about 365 nm and 660 nm by quantum level emission is used.
Can be realized. In a particularly preferred embodiment, if both layers are InGaN, InGaN is GaN,
The crystal is softer than the AlGaN crystal. Therefore the first
Since the thickness of AlGaN, which is the p-type layer, can be increased, laser oscillation can be realized.

When the well and the barrier layer are made of InGaN, the following effects are also obtained. GaN and InGaN have different crystal growth temperatures. For example, in the MOVPE method, InGaN
Grows at 600-800 ° C. while GaN grows
Grow at temperatures above 800 ° C. Therefore, InG
In order to grow a barrier layer made of GaN after growing a well layer made of aN, it is necessary to raise the growth temperature. When the growth temperature is increased, the previously grown InG
Since the aN well layer is decomposed, it is difficult to obtain a well layer having good crystallinity. Further, the thickness of the well layer is only several tens of angstroms, and it becomes difficult to manufacture the MQW when the well layer of the thin film is decomposed. In contrast, the barrier layer is made of InG
With aN, the well layer and the barrier layer can be grown at the same temperature. Therefore, since the well layer formed earlier does not decompose, an MQW with good crystallinity can be formed. This shows the most preferred embodiment of MQW.

The thickness of the active layer 4 is desirably 100 Å or more, preferably 500 Å or more, and more preferably 700 Å or more. By growing the active layer of MQW thickly, the vicinity of the outermost layer of the active layer acts as a light guide layer. Although the upper limit of the thickness of the active layer is not particularly limited, it is usually desirable to adjust the thickness to 0.5 μm or less.

Further, the thickness of the well layer is preferably adjusted to 70 angstrom or less, more preferably 50 angstrom or less. It is also desirable that the thickness of the barrier layer be adjusted to 150 angstrom or less, more preferably 100 angstrom or less. If the well layer is thicker than 70 Å or the barrier layer is thicker than 150 Å, the output of the laser device tends to decrease.

The p-type cladding layer 5 is formed on the surface of the current blocking layer 20 and the surface of the stripe-shaped active layer 4 and is in contact with the stripe side surface of the active layer 4. When the p-type cladding layer is configured in this manner, the p-type cladding layer functions as an optical confinement layer for the longitudinal mode and the transverse mode of the active layer 4, and a refractive index guided laser device is realized. Can be reduced. This is an effect peculiar to the current blocking layer and the p-type cladding layer in the laser device of the present invention. The p-type cladding layer is made of a nitride semiconductor having a larger band gap than the active layer, preferably a p-type nitride semiconductor containing Al. More preferably, a binary or ternary mixed crystal of Al _{Y ′} Ga _{1-Y ′} N (0 <Y ′ ≦ 1) is obtained, whereby a crystal having good crystallinity can be obtained, and refraction with the active layer can be obtained. It is effective for confining the laser light by increasing the rate difference, and it is usually desirable to grow the layer with a thickness of 0.1 μm to 1 μm. The p-type nitride semiconductor is Mg,
It is obtained by doping during the crystal growth with an acceptor impurity composed of a group II element such as Zn, Cd, Be, etc., and annealing at 400 ° C. or more in an inert gas after the crystal growth makes it possible to further reduce the preferable resistance. The mold is obtained.

The p-type contact layer 6 is made of p-type In _x Al _Y Ga
_1-XYN (0 ≦ X, 0 ≦ Y, X + Y ≦ 1). In particular, when p-type GaN doped with Mg is used, a p-type layer having a high carrier concentration is obtained, and 11, a good ohmic contact is obtained, and the threshold current can be reduced. Ni, Pd, I
A metal or alloy having a relatively high work function, such as r, Rh, Pt, Ag, or Au, can easily obtain an ohmic. Incidentally, In _X Ga _1-X N shown in the present invention, Al _Y Ga _1-Y N, etc.,
It merely shows a general formula, and even if different layers are expressed by the same general formula, their values X and Y values never indicate the same value.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for obtaining a laser device according to the present invention will be described below with reference to the drawings. FIGS. 2 to 5 and FIGS. 7 to 8 are schematic cross-sectional views showing the structure of a main part of a wafer having a laser device according to an embodiment of the present invention. FIG. 1 shows a diagram obtained in one step. Further, these figures all show the structure when the element is cut in a direction perpendicular to the stripe of the active layer. The laser device of the present invention merely shows a basic structure, and is not limited to this structure. For example, a layer made of another nitride semiconductor, such as a buffer layer and a cladding layer, may be inserted as needed.

Example 1 (First Step) A substrate 1 having a main surface of sapphire A was prepared, and the substrate 1 was placed in a reaction vessel of a MOVPE apparatus. gallium)
And a buffer layer (not shown) made of GaN on the surface of the sapphire substrate 1 at a temperature of 500 ° C. using ammonia.
It is grown to a thickness of 00 Å.

Subsequently, the temperature was raised to 1050 ° C., and TMG, ammonia, and SiH as donor impurities were added to the source gas.
_{4 An} n-type contact layer 2 made of Si-doped GaN is grown to a thickness of 4 μm using (silane) gas.

Next, the temperature is set to 750 ° C., and TMG, TMI (trimethylindium) and ammonia are used as source gases, silane gas is used as impurity gas, and Si-doped In0.
A crack preventing layer (not shown) made of 1Ga0.9N
It is grown to a thickness of 00 Å. The anti-crack layer is an n-type nitride semiconductor containing In, preferably In
Growing with GaN makes it possible to grow the n-type cladding layer 3 made of a nitride semiconductor containing Al which is to be grown next with a thick film without cracking, which is very preferable. The crack prevention layer is preferably grown to a thickness of 100 Å or more and 0.5 μm or less. If the thickness is less than 100 Å, it is difficult to act as a crack prevention as described above,
If it is thicker, the crystals themselves tend to blacken. In addition,
This crack prevention layer can be omitted depending on the growth method and the growth apparatus. Therefore, although not shown, it is preferable to grow the LD when forming an LD.

Next, an n-type cladding layer 3 made of Si-doped n-type Al0.3 Ga0.7 N is formed to a thickness of 0.5 μm using TMG, TMA (trimethylaluminum) and ammonia as source gases and silane gas as an impurity gas. Grow with.

Next, the active layer 4 is grown using TMG, TMI, and ammonia as the source gas. The active layer 4 has a temperature of 7
While maintaining the temperature at 50 ° C., first, a well layer made of non-doped In0.2Ga0.8N is grown to a thickness of 25 Å. Next, a barrier layer made of non-doped In0.01Ga0.95N was deposited at the same temperature by changing only the molar ratio of TMI.
It is grown to a thickness of 0 Å. This operation 9
This is repeated twice, and finally, a well layer is grown to grow an active layer 4 having a multiple quantum well structure with a total film thickness of 700 Å. Since the thickness of the active layer 4 is adjusted to 500 Å or more, a well layer near the outermost layer,
The barrier layer acts as a light guide layer.

(Second Step) After the active layer 4 is grown, the wafer is taken out of the reaction vessel, and a first protective film 31 made of SiO ₂ having a stripe width of 5 μm is formed on the surface of the active layer 4.
Is formed using a photolithography technique. FIG.
Is a schematic cross-sectional view showing a structure of a main part of the wafer on which the first protective film 31 is formed.

Next, the wafer on which the first protective film 31 has been formed is transferred to RIE (reactive ion etching apparatus), and a portion where the first protective film is not formed is selectively etched. The etching depth is 0.1 μm for the n-type cladding layer 3.
m Adjust to the etched depth. FIG. 3 is a cross-sectional view showing the structure of the main part of the wafer after the completion of the etching. As shown in FIG. 3, a waveguide region having a stripe width of 5 μm is formed in the active layer by this etching.
Next, the surface of n-type clad layer 3 on which the current blocking layer is grown is exposed.

(Third Step) After the completion of the etching, the wafer is transferred into the reaction vessel again, and the current blocking layer 20 is grown on the surface of the n-type clad layer 3 exposed by the etching. The temperature is set to 1050 ° C., and a current blocking layer 2 made of Zn-doped i-type Al 0.5 Ga 0.5 N using TMG, TMA, ammonia and DEZ (diethyl zinc) as an impurity gas.
0 is grown to a thickness of 500 angstroms. FIG. 4 is a sectional view showing the structure of the main part of the wafer after the current blocking layer 20 is grown.

Here, the effects of the case where the current blocking layer is grown thicker than the height of the active layer and the case where the current blocking layer is grown thinner as in the present invention will be compared. 5 and 6 are schematic cross-sectional views showing the periphery of the stripe of the active layer 4 in an enlarged manner. FIG. 5 shows a case where the active layer 4 is grown thin, and FIG. 6 shows a case where the active layer 4 is grown thick for comparison. FIG. First, as shown in FIG. 6, when the current blocking layer 20 'is grown with a thickness exceeding the height of the active layer 4, the surface of the current blocking layer 20' near the stripe of the active layer as shown at 20A 'after growth is formed. Tend to have convex portions. This is because a selective growth is performed by forming a protective film such as SiO ₂ having a property that a nitride semiconductor does not grow on the active layer. That is, since the nitride semiconductor does not grow on the side surface of the protective film, the current blocking layer 20 'grows unevenly. Therefore, when a p-type cladding layer is grown on the current blocking layer 20 'having such irregularities, current flows unevenly due to the irregularities, and a leak, a short circuit, and the like of the laser element tend to occur. On the other hand, as shown in FIG. 5, if the height does not exceed the height of the active layer, the current blocking layer 20 can be uniformly grown, so that such a problem does not occur.

(Fourth Step) After the current blocking layer 20 is grown, the wafer is taken out of the reaction vessel and the first protective film 31 is removed. After that, transfer the wafer again into the reaction vessel,
The p-type cladding layer 5 is grown on the current blocking layer 20 and the active layer 4. The temperature was raised to 1050 ° C, TMG, TMA,
Ammonia, Cp2Mg as acceptor impurity source
(Cyclopentadienylmagnesium), the p-type cladding layer 5 made of Mg-doped Al0.3Ga0.7N was placed at 0.1.
It is grown to a thickness of 5 μm. This p-type cladding layer 5
The raw material gas is also grown on the side surfaces of the stripe of the active layer 4 due to the wraparound of the source gas, and effectively acts as a lateral mode light confinement layer.

Subsequently, TMG, ammonia, Cp2Mg
Is used to grow a p-type contact layer 6 of Mg-doped p-type GaN with a thickness of 0.5 μm. FIG. 7 is a sectional view showing the structure of the main part of the wafer after the growth of the p-type contact layer 6.

The wafer on which the nitride semiconductor is laminated as described above is taken out of the reaction vessel, and as shown in FIG.
A second layer made of SiO2 is formed on the uppermost p-type contact layer.
Is formed, and the portion of the nitride semiconductor where the protective film is not formed is etched by RIE to expose the surface of the n-type contact layer 2 where the n-electrode 10 is to be formed. FIG. 8 is a cross-sectional view showing the structure of the main part of the wafer after the completion of the etching.

Thereafter, a striped n-electrode 10 made of Ti / Au is formed on the surface of the n-type contact layer 2 according to a conventional method.
Stripe-shaped Ni / Au is formed on the surface of the p-type contact layer 6.
And a p-electrode 11 made of the same. Thereafter, the wafer is cleaved to form a resonance surface on a surface perpendicular to the stripe-shaped electrodes, and a dielectric multilayer film is provided on the resonance surface, and then separated into chips to obtain a laser device of the present invention. . When the pulse oscillation of this laser device was performed, the threshold current of the oscillation threshold was 1/5 of that of the conventional electrode stripe type laser device.
Thereafter, the forward voltage was reduced to 1/4 or less, and the oscillation was in a single mode.

Embodiment 2 FIG. 9 is a schematic sectional view showing another structure of the laser device of the present invention. This laser element is different from the laser element of FIG. 1 in that a second p-type nitride semiconductor layer 52 having the same stripe as the active layer 4 on the active layer 4 and having a larger band gap than the active layer is formed. Where you are.

The second p-type nitride semiconductor layer 52 is also made of Al
Containing nitride, preferably Al _Y Ga _1-Y N (0 <
Y <1) is preferable, and the film is preferably grown to a thickness of 50 Å to 1 μm. The band gap of the second p-type nitride semiconductor may be larger than that of the active layer. More preferably, the band gap of the p-type clad layer 5 is increased.
Effectively acts as a vertical light confinement layer. By growing the second p-type nitride semiconductor layer 52 having a larger band gap than the active layer in this manner, the thickness of the p-type layer in the vertical direction is increased and the efficiency of substantial light confinement is improved.

The growth of the second p-type nitride semiconductor layer is extremely simple, and the active layer 4 is formed in the first step of the first embodiment.
After the growth of TMG, TMG, T
Using MA, ammonia, Cp2Mg, Al0.4Ga0.
A layer of 6N is grown for 100 Å.
Next, similarly to the first embodiment, the second p-type nitride semiconductor layer 52 and the active layer 4 are etched in a stripe shape,
The n-type cladding layer 3 is exposed. Thereafter, the laser device shown in FIG. 9 was obtained in the same manner as in Example 1. As a result, the characteristics were almost the same as those in Example 1.

[0037]

As described above, in the laser device of the present invention, by providing the thin current blocking layer on the n-layer side, the p-type cladding layer is in contact with the stripe side surface of the active layer. The laser in the transverse mode can be controlled to lower the oscillation threshold. In addition, since the current blocking layer does not exceed the height of the active layer as shown in FIG. 5, the nitride semiconductor layer grown on the current blocking layer can be grown with a uniform film thickness. Sex is also greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a laser device according to one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a structure of a main part of a wafer obtained in one step of the manufacturing method of the present invention.

FIG. 3 is a schematic cross-sectional view showing a structure of a main part of a wafer obtained in one step of the manufacturing method of the present invention.

FIG. 4 is a schematic sectional view showing a structure of a main part of a wafer obtained in one step of the manufacturing method of the present invention.

FIG. 5 is an enlarged partial cross-sectional view showing the vicinity of a stripe of an active layer in FIG. 4;

FIG. 6 is a partial schematic cross-sectional view showing a periphery of a stripe of an active layer by another manufacturing method in comparison with FIG.

FIG. 7 is a schematic sectional view showing a structure of a main part of a wafer obtained in one step of the manufacturing method of the present invention.

FIG. 8 is a schematic sectional view showing a structure of a main part of a wafer obtained in one step of the manufacturing method of the present invention.

FIG. 9 is a schematic sectional view showing a structure of a laser device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... n-type contact layer 3 ... n-type cladding layer 4 ... Active layer 5 ... p-type cladding layer 6 ... p-type contact layer 20 .... Current blocking layer

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50 H01L 33/00 JICST file (JOIS)

Claims (3)

(57) [Claims] At least an n-type nitride semiconductor layer is exposed on an upper part of a substrate by etching.
In a nitride semiconductor laser device having a double hetero structure having a stripe-shaped active layer formed by exposing and a p-type nitride semiconductor layer in order, an active layer is formed on both sides of the stripe of the active layer. In the range closer to the n-type nitride semiconductor side than the top layer ,
A film thickness on the exposed surface of the n-type nitride semiconductor layer.
I-type In _x Al _y Ga _1-xy N (y ≧ 0.5 μm)
0.4 . A nitride semiconductor laser device comprising: a current blocking layer made of 0.4) ; and a p-type nitride semiconductor layer formed on both sides of the stripe of the active layer. 2. A second p-type nitride semiconductor layer having the same stripe as that of the active layer between the p-type nitride semiconductor layer and the active layer and having a larger band gap than the active layer. The nitride semiconductor laser device according to claim 1, wherein the nitride semiconductor laser device is formed. 3. A first step of sequentially growing at least an n-type nitride semiconductor layer and an active layer on a substrate, and a protective film having a stripe width on the active layer after the first step.
A second step of forming and etching a portion where the protective film is not formed in a stripe shape, and exposing a surface of the n-type nitride semiconductor layer; and, after the second step, an n-type nitride exposed by etching. An i-type In _x A film having a thickness of 0.5 μm or less is formed on the surface of the semiconductor layer.
a third step of growing at l _y Ga _1-xy N range close to the n-type nitride semiconductor layer side of the uppermost (y ≧ 0.4) active layer current blocking layer made of, after the third step A fourth step of growing a p-type nitride semiconductor layer on the current blocking layer so as to be in contact with the stripe side surface of the active layer;
A method for manufacturing a nitride semiconductor laser device, comprising the steps of: