JP2001148545A - Nitride semiconductor laser element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable single-peak vertical transverse mode of a nitride semiconductor laser element, lower the laser oscillation threshold current density and a stable single-peak horizontal transverse mode, by light confinement in the horizontal transverse mode. SOLUTION: Selective growth is made with a metallic mask 113, provided on an n-type contact layer 102, thereby lowering the dislocation density. The metallic mask 113 is provided below a stripe-like electrode, to absorb leaking lights and stabilize the single peak vertical transverse mode, a metallic mask is provided in an n-type clad layer 103 or a p-type clad layer 107 to allocate portions, having no metallic mask below the stripe-like electrode and lights from an active layer are absorbed to strengthen light confining in the horizontal transverse mode. A metal film is covered with an insulative film to relax the mask stripe direction dependence of the lateral growth and obtain a current- constricting function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor laser device made of a nitride semiconductor having excellent temperature characteristics at a high temperature and used as a light source for a display device, a display, an optical disk, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, nitride semiconductors have been used or studied as materials for light emitting devices and high power devices. For example, in the case of a light emitting element, it can be used as an element capable of emitting light in a wide range from blue to orange by adjusting the composition of the light emitting element. Utilizing such characteristics, blue light emitting diodes, green light emitting diodes, and the like have been put to practical use in recent years, and blue-violet semiconductor lasers have been developed as nitride semiconductor laser devices.

[0003] Among these, a nitride semiconductor laser device in which the dislocation density in a crystal is reduced by applying a selective growth technique using SiO ₂ is disclosed, for example, in Appl.
Phys. Lett. 72 (1998) p211-p
213. In this report, a selective growth mask made of SiO ₂ is formed on an n-type GaN film, and an n-type GaN film is re-grown thereon to cover the SiO ₂ mask to produce a flat surface. _A laser structure is formed on the coating of the _two masks. By using this method, defects in the laser element are reduced and the laser element characteristics are improved.

Further, in order to reduce the operating current of the semiconductor laser device and stabilize the horizontal and transverse modes (the direction parallel to the active layer), a semiconductor laser device having a structure as shown in FIG. 15 has been conventionally used. . This semiconductor laser device includes a substrate 10, a low-temperature buffer layer 11, an n-type GaN contact layer 12, an n-type AlGaN cladding layer 13, an n-type GaN optical guide layer 14, an active layer 15, an AlGaN carrier block layer 16, a p-type GaN optical layer. Guide layer 17, p-type AlGaN
It comprises a cladding layer 18, a p-type GaN contact layer 19, an insulating film 20, an n-type electrode 21, and a p-type electrode 22. However, the above Appl. Phys. Lett. 7
2 (1998) p211-p213, a SiO ₂ mask is inserted into the n-type contact layer 12 and the n-type A
GaN / AlGaN instead of lGaN cladding layer 13
A cladding layer is formed by a superlattice.

[0005] Such a laser structure is called a ridge stripe structure. According to the ridge stripe structure, the width Wp of the stripe electrode is reduced to about 2 μm,
Drilling the p-type cladding layer 18 close to the p-type light guide layer 17 narrows the current injection into the active layer 15,
The operating current of the laser can be reduced. Also, p
In the region 24 dug down near the shaped light guide layer 17 and the ridge stripe region 23, a difference occurs in the equivalent refractive index of the active layer 15 and the horizontal transverse mode is confined.
A single (single peak) horizontal / lateral mode can be stabilized.

On the other hand, in the vertical transverse mode (the direction perpendicular to the active layer), in order to obtain a stable single (single peak) mode in a general nitride semiconductor laser device including the above-mentioned ridge stripe type laser structure. A method of increasing the average Al composition ratio in the cladding layer or increasing the thickness of the cladding layer to prevent the leakage of vertical and transverse mode light is adopted. In particular, in the latter method, when the layer thickness of the n-type cladding layer is small, the vertical transverse mode light leaks into the n-type contact layer between the substrate and the n-type cladding layer. The leaked vertical transverse mode light is transmitted to the cladding layer (for example, n
A layer (for example, a film thickness of 0.3) having a refractive index larger than the equivalent refractive index of the cladding layer outside the AlGaN cladding layer).
In the case where an In _x Ga _1-x N (0 ≦ x ≦ 1) layer having a thickness of μm or more is provided, in the FFP (far field pattern), a sub-peak appears on the wide-angle side to improve the unimodality of the vertical and transverse modes. Spoil. FIGS. 16 (b) and 17 (b) show NFP (near field pattern) and FFP in a conventional nitride semiconductor laser device. As shown in these figures, sub-peaks are observed.

[0007]

However, increasing the average Al composition ratio in the cladding layer or increasing the thickness of the cladding layer in order to obtain a single-peak and stable vertical / transverse mode causes a lattice failure. Cracks are caused by the matching, crystallinity is reduced due to an increase in crystal defects, and the resistance of the device is increased. As a result, the laser threshold current is increased. From this, A that can be manufactured as a laser element
The growth conditions for the cladding layer containing 1 were limited, and a sufficiently unimodal and stable vertical and transverse mode could not be obtained.

On the other hand, Appl. Phys. Le
tt. 72 (1998) p211-p213, the cladding layer based on the GaN / AlGaN superlattice suppresses the generation of cracks as compared with a case where a normally used AlGaN cladding layer has the same average Al composition ratio. The thickness of the cladding layer can be increased. But,
Since Al generally has a strong gas phase reaction and is a superlattice, the superlattice period fluctuates due to valve switching, and the average A
The 1 composition ratio also changes. Therefore, it is difficult to grow a crystal of a superlattice containing Al, and it is difficult to obtain reproducibility of the cladding layer thickness and the average Al composition ratio in the cladding layer. Also, Ga
Even with a cladding layer made of an N / AlGaN superlattice, an increase in the Al composition ratio and a decrease in crystallinity due to an increase in the thickness of the cladding layer and an increase in the resistance of the element are unavoidable.

On the other hand, the stabilization of the horizontal transverse mode using the ridge stripe structure reduces the refractive index difference exceeding the decrease in the refractive index due to the increase in the density of stenotically injected carriers by digging the cladding layer close to the p-type optical guide layer. Ridge stripe structure. Therefore, the stabilization of the horizontal and transverse modes depends on the thickness of the dug-down cladding layer. However, since such a ridge stripe structure is generally formed by dry etching, it is difficult to control the thickness of the deep clad layer, and the reproducibility of the layer thickness is poor. As a result, the horizontal transverse mode is unstable. Was. In addition, in order to produce a ridge stripe structure using etching,
The exposed end face is deteriorated, and the laser device threshold characteristics are adversely affected, for example, the laser oscillation threshold current density is increased. Further, in order to reduce the laser oscillation threshold current density, stronger light confinement has been required.

The instability of these transverse modes is caused by the problem shown in FIG.
(B) and NFP and FFP as shown in FIG.
This is very problematic for a device such as an optical disk to which a laser is applied because the sub-peak is generated.
For this reason, stable lateral mode controllability has been desired.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and it is an object of the present invention to provide a nitride semiconductor laser device capable of obtaining a single-peak stable vertical and transverse mode and a method of manufacturing the same. Aim. It is still another object of the present invention to provide a nitride semiconductor laser device capable of obtaining a laser oscillation threshold current density by confining light in a horizontal transverse mode and obtaining a single-peak stable horizontal transverse mode, and a method of manufacturing the same.

[0012]

The nitride semiconductor laser device according to the present invention has a semiconductor laminated structure made of a nitride semiconductor on a substrate, and at least an optical signal is provided in a region where guided light reaches in the semiconductor laminated structure. A mask including a metal film having an absorption function is provided, thereby achieving the above object.

In the nitride semiconductor laser device according to the present invention, the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown, and the semiconductor laminated structure is an active layer sandwiched between a pair of clad layers and both clad layers. Having a stripe-shaped electrode on the surface of the semiconductor laminated structure opposite to the substrate, in contact with the lower surface of the clad layer closer to the substrate, having a higher refractive index than the clad layer, and
A contact layer having a refractive index different from that of the substrate, at a position below the stripe-shaped electrode and within a half of the contact layer thickness from the interface between the cladding layer and the contact layer toward the substrate. Whether the metal film is placed,
In contact with the lower surface of the cladding layer closer to the substrate, a contact layer having a higher refractive index than the cladding layer and having substantially the same refractive index as the substrate has a contact layer below the stripe-shaped electrode. The metal film is disposed at a position within half of the total thickness of the contact layer thickness and the substrate thickness from the interface between the cladding layer and the contact layer toward the substrate or close to the substrate. The other cladding layer has a lower refractive index than the substrate, and there is no contact layer between the substrate and the cladding layer, below the stripe-shaped electrode, and the cladding layer and the substrate The metal film is disposed at a position within half of the thickness of the substrate from the interface of the substrate toward the lower surface of the substrate, or on the clad layer below the stripe-shaped electrode and closer to the substrate. Or in its cladding layer Ri, can be from a lower surface of the active layer to 0.5μm or more positions toward the substrate, a structure in which the metal film is arranged.

In the nitride semiconductor laser device according to the present invention, the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown, and the semiconductor laminated structure has an active layer sandwiched between a pair of clad layers and both clad layers. Having a ridge stripe portion above the active layer, in contact with the lower surface of the clad layer closer to the substrate, having a higher refractive index than the clad layer, and having a different refractive index from the substrate. Having a contact layer, the metal film is disposed at a position below the ridge stripe portion and within a half of the contact layer thickness from the interface between the cladding layer and the contact layer toward the substrate, A contact layer having a higher refractive index than the cladding layer and having substantially the same refractive index as the substrate, in contact with the lower surface of the cladding layer closer to the substrate; A lower di stripe portion,
The metal film is arranged at a position within half of the total thickness of the contact layer thickness and the substrate thickness from the interface between the cladding layer and the contact layer toward the substrate, or the cladding closer to the substrate. The layer has a lower refractive index than the substrate, and there is no contact layer between the substrate and the cladding layer, below the ridge stripe portion and from the interface between the cladding layer and the substrate. Whether the metal film is arranged at a position within half of the thickness of the substrate toward the lower surface of the substrate,
Or, below the ridge stripe portion, and
0.5 μm from the lower surface of the active layer toward the substrate, on or within the cladding layer closer to the substrate.
A configuration in which the metal film is arranged at the above positions can be adopted.

In the nitride semiconductor laser device according to the present invention, the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown, and the semiconductor multilayer structure has an active layer. Has a stripe-shaped electrode on the opposite side, the metal film is disposed at a position within 2 μm from the lower surface or the upper surface of the active layer, and a mask including the metal film is provided below the stripe-shaped electrode. A configuration in which a portion not covered with the mask is provided may be employed.

In the nitride semiconductor laser device according to the present invention, the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown, and the semiconductor laminated structure has an active layer sandwiched between a pair of clad layers and both clad layers. Having a ridge stripe portion above the active layer, wherein the metal film is disposed at a position within 2 μm from the lower surface or the upper surface of the active layer, and the mask including the metal film comprises the ridge stripe portion. May be arranged so as to have a portion that is not covered with the mask below the mask.

In the nitride semiconductor laser device of the present invention, it is preferable that the interval between the masks is 1 μm or more and 15 μm or less.

In the nitride semiconductor laser device of the present invention, it is preferable that the thickness of the metal film is 0.01 μm or more, and the thickness of the entire mask including the metal film is 2 μm or less.

In the nitride semiconductor laser device of the present invention, the metal film may be made of W, Ti, Mo, Ni, Al, Pt, P
A metal material containing at least one of d, Au and their alloys, or a composite film composed of a plurality of layers containing at least one of these metals and alloys can be used.

In the nitride semiconductor laser device according to the present invention, the mask may have a structure in which an upper portion of the metal film is covered with an insulating film.

In the nitride semiconductor laser device of the present invention, the insulating film made of SiO ₂ or SiN _x can be used.

In the nitride semiconductor laser device according to the present invention, the metal film may have a thickness <1.1 with respect to the underlying nitride semiconductor layer.
It is preferably provided in a stripe shape in the <00> direction.

In the nitride semiconductor laser device of the present invention, the mask including the metal film may not be covered with the nitride semiconductor layer on the mask, but may have a recess.

A method for manufacturing a nitride semiconductor laser device according to the present invention is a method for manufacturing a nitride semiconductor laser device according to the present invention. The above object is achieved by using 10% or more of a nitrogen carrier gas.

Hereinafter, the operation of the present invention will be described.

According to the present invention, in a semiconductor laminated structure made of a nitride semiconductor, a region where guided light reaches is provided.
By providing a mask including a metal film having at least a light absorption function, a single horizontal / lateral mode or a single vertical / lateral mode is stabilized by absorbing light leakage or light from the active layer, thereby confining light in the horizontal / lateral mode. It is possible to do.

The light absorption effect in the vertical and transverse modes hardly depends on the position where the metal film is formed, but only on the thickness of the metal film. However, single-mode vertical / horizontal mode (single mode)
Since it depends on the position where the metal film is formed, it is preferable to be as close as possible to the active layer.

Therefore, (1) When a contact layer having a refractive index higher than that of the clad layer and having a refractive index different from that of the substrate is provided in contact with the lower surface of the clad layer closer to the substrate, A metal film having a light absorbing function is arranged below the stripe-shaped electrode and at a position within half of the contact layer thickness from the interface between the cladding layer and the contact layer toward the substrate. In this case, the refractive index of the substrate may be higher or lower than that of the cladding layer as long as it is different from that of the contact layer. (2) In the case where a contact layer having a higher refractive index than the clad layer and having substantially the same refractive index as the substrate is provided in contact with the lower surface of the clad layer closer to the substrate, A metal film having a light absorbing function is arranged below the stripe-shaped electrode and at a position within half of the total thickness including the contact layer thickness and the substrate thickness from the interface between the cladding layer and the contact layer toward the substrate. In this case, if the thickness of the substrate is larger than the contact layer, a mask is disposed in the substrate. However, the mask may be disposed when forming the substrate (for example, a GaN thick film). (3) If such a contact layer is not provided and the cladding layer closer to the substrate has a lower refractive index than the substrate, the cladding layer and the substrate are located below the stripe-shaped electrode. A mask including a metal film having a light absorbing function is arranged at a position within half the thickness of the substrate from the interface of the substrate toward the lower surface of the substrate.
In this case as well, a mask is arranged in the substrate, but the mask may be arranged when forming the substrate (for example, a GaN thick film) as described above. This also means that
It is possible to realize a single peak in the vertical and horizontal modes. Further, by using a metal material in which a nitride semiconductor does not directly grow epitaxially as the metal film, dislocation density can be reduced by a mask and laser life characteristics can be improved. In the case of the above (1), the metal film is disposed at a position within half the thickness of the contact layer because it depends on the refractive index of the contact layer in contact with the cladding layer. If the refractive index of the substrate is substantially the same as that of the substrate, the metal film is considered as an integral body.
In the case of (1), the substrate comes into contact with the cladding layer because there is no contact layer, and the substrate becomes the same as the above-mentioned contact layer. That is, although the names of the contact layer and the substrate are different,
Substantially, attention is paid only to the refractive index of the layer referred to by that name.

Here, when the metal film is provided on the clad layer closer to the substrate or in the clad layer, if the metal film is arranged at a position of less than 0.5 μm from the lower surface of the active layer toward the substrate, the metal film Due to the light absorption effect, gain loss in laser oscillation increases, which causes an increase in laser oscillation threshold current density. Therefore, when the metal film is arranged on or in the cladding layer closer to the substrate, the metal film is located at a position of 0.5 μm or more below the stripe-shaped electrode and from the lower surface of the active layer toward the substrate. Deploy.
In this specification, the surface near the substrate is the lower surface,
The surface opposite to the lower surface is called the upper surface.

In the ridge stripe structure, when a contact layer having a refractive index higher than that of the cladding layer and having a refractive index different from that of the substrate is provided in contact with the lower surface of the cladding layer closer to the substrate. A metal film having a light absorbing function is disposed below the ridge stripe portion and at a position within a half of the contact layer thickness from the interface between the cladding layer and the contact layer toward the substrate. In the case where a contact layer having a higher refractive index than the clad layer and having substantially the same refractive index as the substrate is provided in contact with the lower surface of the clad layer closer to the substrate, the ridge stripe portion , A metal film having a light absorbing function is disposed at a position within half of the total thickness of the contact layer thickness and the substrate thickness from the interface between the cladding layer and the contact layer toward the substrate. Also, when such a contact layer is not provided and the cladding layer closer to the substrate has a lower refractive index than the substrate, it is located below the ridge stripe portion and from the interface between the cladding layer and the substrate. A metal film having a light absorbing function is arranged at a position within half the thickness of the substrate toward the lower surface of the substrate. Alternatively, a metal having a light absorbing function is provided at a position of 0.5 μm or more from the lower surface of the active layer toward the substrate, on the cladding layer closer to the substrate, below the ridge stripe portion, and in the cladding layer. Place the membrane. This makes it possible to realize a single peak in the vertical and horizontal modes. Further, by using a metal material in which a nitride semiconductor does not directly epitaxially grow as the metal film,
The mask can reduce the dislocation density and improve the laser life characteristics. Furthermore, the ridge stripe structure stabilizes the horizontal and transverse modes and achieves the oscillation threshold current density.

Further, when a portion not covered with the metal film is provided below the stripe-shaped electrode or the ridge stripe portion, if a metal film having a light absorbing function is arranged at a position more than 2 μm from the lower surface or the upper surface of the active layer, There is almost no difference in transmission refractive index between the place where the mask is provided and the place where the mask is not provided, and the light confinement effect in the horizontal / lateral mode is weakened. Therefore, a metal film having a light absorbing function is arranged at a position within 2 μm from the lower surface or the upper surface of the active layer, and a portion not covered with the metal film is provided below the stripe-shaped electrode or the ridge stripe portion, so that the horizontal and horizontal directions are provided. It is possible to increase the mode optical confinement and reduce the laser oscillation current density.

In this case, according to the experiments by the present inventors,
When the mask interval (interval between metal films) was 1 μm or more and 15 μm or less, the horizontal / lateral mode was stabilized.

When the thickness of the metal film is 0.01 μm or more, it is possible to increase the absorptance of laser light and to stabilize the single-peak vertical and transverse mode. When the thickness of the entire mask including the metal film is 2 μm or less, a flat surface can be obtained when the mask is covered with the nitride semiconductor film.

Generally, the manufacturing temperature of the nitride semiconductor film is 10
Since the temperature is about 00 ° C., it is preferable to use a metal material that can sufficiently withstand this temperature. Examples of such a metal material include W, Ti, Mo, Ni, Al, Pt, Pd,
Au, an alloy thereof, or a composite film including a plurality of layers containing the metal or the alloy can be used.

Further, in a metallic mask made of, for example, tungsten or the like, the effect of suppressing the growth of GaN is very strong, and the dependence of the mask on the stripe direction is also strong. Regarding the dependence on the stripe direction, <11-
When a mask pattern is formed in the <20> direction, almost no lateral growth (growth in a direction parallel to the substrate) occurs,
It is difficult to cover the mask with a GaN film. Therefore, if the metal film is coated with an insulating film to form a metal mask with an insulating film, such a growth suppressing effect and stripe direction dependency can be reduced. In addition, regarding the position of the metal mask with an insulating film, the arrangement of the metal film is important, and it is preferable to arrange the metal film at the above-described position.

As the insulating film, SiO ₂ or SiN _x
The use of is preferable because the shift of the crystal orientation (crystal growth axis) of the nitride semiconductor film coated on the insulating film is suppressed.

Further, if a mask (metal film) is provided in a stripe shape in the <1-100> direction on the underlying nitride semiconductor layer, lateral growth of the nitride semiconductor layer on the mask is accelerated, and Speed increases.

The above-mentioned metallic mask or metallic mask with an insulating film is not flatly covered by the nitride semiconductor layer thereabove and may have a depression. In this case, it is possible to reduce the crystal strain of the regrown nitride semiconductor layer formed thereon by the depression. Therefore, a decrease in crystallinity due to distortion can be prevented, and the laser oscillation life can be further lengthened.

In the method of manufacturing a nitride semiconductor laser device according to the present invention, when covering the mask with a nitride semiconductor layer, a nitrogen carrier gas of 10% or more of the total carrier gas is used. Lateral growth of the nitride semiconductor layer on the mask is accelerated, and the coating speed is increased.

[0040]

Embodiments of the present invention will be described below.

Generally, when growing a nitride semiconductor crystal, sapphire, 6H-SiC, 4H-SiC, 3C
-SiC, GaN, Si, Ge, GaAs, MgAl 2
O ₄ or the like is used as the substrate. The crystal growth is usually performed by a metal organic chemical vapor deposition (hereinafter, referred to as MOCVD), a molecular beam epitaxy (MBE), a hydride vapor phase epitaxy (H-VPE), or the like. Among them, considering the crystallinity and mass productivity of the obtained nitride semiconductor, sapphire or GaN is used as the substrate,
The most common growth method is the MOCVD method.

In the following embodiments, an example of a nitride semiconductor laser device in which a nitride semiconductor is grown on a sapphire substrate or a GaN substrate by MOCVD will be described. In the first, second, and fourth to seventh embodiments, examples using a sapphire substrate have been described. However, it was confirmed that similar effects can be obtained by using the other substrates described above. ing. In particular, when a GaN substrate was used, as described in a thirteenth embodiment to be described later, since the crystals were the same kind of crystal, favorable results were obtained with good lattice matching. In the third embodiment and the tenth to twelfth embodiments, examples using a GaN substrate have been described. However, it has been confirmed that similar effects can be obtained by using the other substrates described above.

(Embodiment 1) In this embodiment, a nitride semiconductor laser device in which the vertical and horizontal modes are stabilized (single peak) by using a metallic mask having a light absorbing function will be described.

FIG. 1 shows a nitride semiconductor laser device according to this embodiment.
This shows the structure of the child. This nitride semiconductor laser device
A low-temperature GaN buffer layer 101 on a fire substrate 100;
n-type GaN contact layer 102, n-type Al_0.1Ga_0.9N
Clad layer 103, n-type GaN light guide layer 104, active
Layer 105 (for example, a 2 nm thick In_0.15Ga
_0.85N layer and 4 nm thick In_0.02Ga_0.98Consists of N layers
Multiple quantum well active layer, 4 nm thick In_0.15G
a_0.85N layer and 10 nm thick In_0.01Ga_0.993 N layers
Periodically formed ones can be used), Al_0.2
Ga_0.8N carrier block layer 106, p-type GaN optical gas
Id layer 107, p-type Al_0.1Ga_0.9N cladding layer 108
And the p-type GaN contact layer 109 are sequentially laminated
I have. The p-type cladding layer 108 is near the p-type light guide layer 107
The p-type contact layer 109 and
The ridge stripe formed by the p-type cladding layer 108 is shaped
Has been established. SiO on top_TwoInsulating film 11 made of
0 is provided and the upper part of the ridge stripe is opened.
You. On the insulating film 110 and the opening of the insulating film 110
Over the ridge stripe exposed from the
The pole 112 is provided, and the portion on the ridge stripe is
It functions as a tripe-shaped electrode. On the other hand, p-type contour
From the contact layer 108 to the n-type contact layer 102.
Partially removed so that the surface of the contact layer 102 is exposed.
And an n-type electrode on the exposed portion of the n-type contact layer 102.
111 are formed.

The n-type contact layer 102 is a lower n-type Ga
A metallic mask (tungsten mask) 113 formed of an N film 102a and a regrown n-type GaN film 102b and provided on the lower film 102a below the ridge stripe portion.
The top is covered with a regrowth film 102b.

FIG. 2 shows the MOC used in this embodiment.
1 shows a schematic configuration of a VD device. In the figure, 201 is (000
1) A sapphire substrate having a surface, which is made of carbon
Is disposed on a susceptor 202 composed of Susceptor
Heater for resistance heating made of carbon is arranged in 202
The substrate temperature can be controlled by a thermocouple.
Wear. Reference numeral 203 denotes a reaction tube made of double quartz, which is water-cooled.
Have been. Ammonia (NH_Three) 2
Using trimethylgallium (T
MG) 207a, trimethyl aluminum (TMA) 2
07b and trimethylindium (TMIn) 207
c with nitrogen gas (N_Two) Or hydrogen gas (H_Two) By bab
Ring used. Mono-type as the n-type doping material
Run (SiH _Four) P-type doping material using 209
As biscyclopentadienyl magnesium (Cp
_TwoMg) 207d was used. Each raw material is mass flow controller
The flow rate is accurately controlled by the roller (MFC) 208
It is introduced into the reaction tube from the raw material inlet 204 and the exhaust gas outlet
It is discharged from 205.

The nitride semiconductor laser device of this embodiment can be manufactured, for example, as follows. First, the sapphire substrate 100 is cleaned and placed in a crystal growth apparatus, and is subjected to a heat treatment at a temperature of about 1100 ° C. for about 10 minutes in a hydrogen atmosphere, and then the temperature is lowered to about 500 ° C. to 600 ° C. After the temperature becomes constant, the carrier gas is changed to nitrogen, nitrogen gas is supplied at a total flow rate of 10 l / min, ammonia is supplied at a rate of 3 l / min, TMG is flowed at about 20 μmol / min, and the low-temperature GaN buffer layer 101 having a thickness of 20 nm is formed. Let it grow.

Next, the supply of TMG was stopped and the temperature was raised to 10 ° C.
The temperature is raised to 50 ° C., and TMG is added again to about 50 μmol / mi.
n and SiH ₄ gas are supplied at about 10 nmol / min,
In the n-type contact layer 102, a lower n-type GaN film 102a having a thickness of 4 μm is grown. After that, the substrate is once taken out of the crystal growing apparatus, and EB (electron beam) is used.
A tungsten film having a thickness of 0.1 μm is formed by an evaporation method. As a method for forming the tungsten film, a sputtering method may be used instead of the EB evaporation method. This tungsten film is etched into a stripe shape with a mask width (M) of 3 μm using a normal photolithography technique,
The lower n-type GaN film 102a is exposed. At this time, the tungsten mask 113 sets the stripe direction to <1-10
0> direction, and arranged below a ridge stripe portion to be formed in a later step. Next, the substrate was placed again in the crystal growth apparatus, and the atmosphere was replaced with nitrogen gas.
The temperature was raised to 1050 ° C. while flowing at 1 / min, and TMG was added at 50 μmol / min and S
iH ₄ gas is supplied at 10 nmol / min and the thickness is 4 μm
The n-type GaN film 102b is regrown. As the growth progressed, GaN started to grow again from the portion not covered with the tungsten mask 113, and lateral growth occurred to cover the tungsten mask 113. The laterally grown GaN film 102b was completely bonded, and the contact layer 102 having a flat surface was obtained.

Subsequently, TMA was supplied at 10 μmol / min.
0.5 μm thick n-type Al_{0. 1}Ga_0.9N clad
A layer 103 is grown. This layer corresponds to the contact layer 102
After the lateral growth, the supply of TMA is started to continuously grow.
I let you. After that, the supply of TMA was stopped and TMG was
mol / min and SiH_Four10 nmol / min gas
N-type GaN optical guide layer 10 having a thickness of about 0.1 μm
Grow 4. After the growth of the light guide layer 104, once TM
G and SiH_FourSupply is stopped and the temperature is increased from 700 ° C to 800 ° C.
℃, supply TMI and TMG, thickness 2nm
In_0.15Ga _0.85N layer and 4 nm thick In_0.02Ga
_0.98Multiple quantum well active layer 10 composed of a plurality of N layers
5 is formed. At this time, SiH_FourMay be supplied,
It is not necessary to supply. Next, supply of TMG and TMI was restarted.
And the temperature is raised again to 1050 ° C.
Supplying TMA to 20nm thick Al_0.15Ga_0.85N
A carrier block layer 106 is grown. this
When Cp_TwoMg may or may not be supplied
No. Note that this carrier block layer 106 is not formed.
There is no particular problem if it is not. Subsequently, the supply of TMA was stopped.
Stop and adjust the supply of TMG to 50 μmol / min,
Cp_TwoMg is supplied at about 50 nmol / min to achieve a thickness of 0.1 mm.
A 1 μm p-type GaN optical guide layer 107 is grown. So
After that, TMA was supplied at 10 μmol / min to achieve a thickness of 0.1 μm.
5 μm p-type Al_0.15Ga_0.85The N cladding layer 108 is formed.
Lengthen. Finally, the supply of TMA was stopped, and the thickness was reduced to 0.1 mm.
A 1 μm p-type GaN contact layer 109 is grown,
Is cooled to room temperature, and the substrate is taken out of the crystal growing apparatus.

Thereafter, the dry etching apparatus is used to
N-type GaN contact layer by reactive ion etching
102 is exposed, and the Al film and the Ti film are
To form an n-type electrode 111. At this time,
Exposing n-type contact layer 102 using on-etching
What makes the sapphire substrate 100 which is an insulating substrate
This is because it was used. Therefore, GaN substrates and SiC substrates
When a substrate having such conductivity is used, an n-type
It is not necessary to expose the tact layer 102, and
An n-type electrode may be formed on the surface. On the other hand, the p-type electrode part
Is a p-type cladding up to the p-type GaN optical guide layer 107.
Layer 108 is etched to form a p-type cladding layer 108 and
And a p-type contact layer 109 formed in a ridge stripe shape
And SiO _Two200 nm thick insulating film 110 made of
Is deposited. Thereafter, the insulating film 110 is partially removed to remove p.
Mold contact layer 109 is exposed, and an exposed portion (Wp = 2
Ni film and Au film are deposited to cover
Thus, a p-type electrode 112 is formed. Finally, the cleavage or de
An end face to be a mirror is formed by light etching. Less than
Above, a blue-violet emission wavelength using nitride semiconductor
The nitride semiconductor laser device of this embodiment
You.

N obtained by such a selective growth step
The surface of the p-type GaN contact layer 102 is flat and free of cracks, and when observed by a transmission electron microscope, dislocations (crystal defects) generated from the interface between the substrate 100 and the low-temperature GaN buffer layer 101 are generated by a tansten mask. Almost no GaN film 102b was observed in the GaN film 102b coated on the substrate 113. In addition, due to the presence of the tansguten mask 113, the dislocation density was reduced by two digits or more in each film constituting the laser structure after regrowth on the mask. Further, the life characteristic of the semiconductor laser device itself is about 1
2000 hours.

When the FFP in the vertical (vertical direction with respect to the active layer) transverse mode was observed for this nitride semiconductor laser device, the laser oscillated in a single-peak single mode as shown in FIG. Thus, in the conventional semiconductor laser device, the subpeak as shown in FIG. 17B observed by the FFP in the vertical / lateral mode was not observed. Further, the nitride semiconductor laser device of the present embodiment was subjected to a life test of 10,000 hours, and the vertical transverse mode was observed again. As a result, a stable single vertical transverse mode similar to the above was observed.

The following are conceivable reasons for this. In the conventional semiconductor laser device, a subpeak is generated in the vertical and transverse modes and cannot be unified because the laser light emitted from the active layer leaks without being sufficiently confined in the vertical direction by the n-type AlGaN cladding layer. That's why. Then, the n-type AlGaN cladding layer 10
N-type GaN having a thickness equal to or greater than 0.3 μm and having an equivalent refractive index greater than that of the n-type AlGaN cladding layer 103 outside
Since the contact layer 102 is provided, the optical n-type Ga
A sub-peak of the vertical / lateral mode light was generated in the N contact layer 102 as shown in FIG. 16B, which hindered the formation of a single peak in the vertical / lateral mode.

On the other hand, the metallic mask having the growth suppressing effect used in the present embodiment is made of tungsten, and the substrate 100 and the n-type AlGaN cladding layer 1 are formed.
The vertical transverse mode light generated (leaked) between the light emitting device and the light emitting device 03 is absorbed by the tungsten mask 113. Thus, in the nitride semiconductor laser device of the present embodiment, FIG.
As shown in FIG. 6A and FIG. 17A, it is considered that the vertical and horizontal modes can be stabilized. Hereinafter, this effect is referred to as a light absorption effect. In addition, it is considered that a single vertical transverse mode that was stable was observed even after a life test of 10,000 hours, in addition to the effect of reducing the dislocation density due to the selective growth.

In order to obtain a single vertical transverse mode of the semiconductor laser device by the light absorption effect of the metallic mask (tungsten mask), the metallic mask is formed in the vertical and horizontal directions with respect to the substrate. Each of them is preferably formed at the following position.

First, in the direction perpendicular to the substrate, (1) a contact in contact with the lower surface of the clad layer closer to the substrate and having a refractive index higher than that of the clad layer and different from that of the substrate; In the case of having a layer, a metallic mask is arranged at a position within half of the thickness of the contact layer from the interface between the cladding layer and the contact layer toward the substrate. For example, when an AlGaN cladding layer and a GaN contact layer are provided on a sapphire substrate, a metallic mask is formed at a position within half the thickness of the GaN contact layer from the interface between them. In this embodiment, n-type AlGaN
A tungsten mask 1 having a thickness of 0.1 μm is placed at a position of 4 μm from the interface between the cladding layer 103 and the n-type GaN contact layer 102 (the lower surface of the n-type cladding layer 103) toward the substrate.
13 are formed.

(2) In the case where a contact layer having a higher refractive index than the clad layer and having substantially the same refractive index as the substrate is provided in contact with the lower surface of the clad layer closer to the substrate, A metallic mask is arranged at a position within half of the total thickness of the thickness of the contact layer and the thickness of the substrate from the interface between the metal mask and the contact layer. For example,
When the AlGaN cladding layer and the GaN contact layer are provided on the GaN substrate, the metallic mask is arranged at a position within half of the total thickness of the GaN contact layer and the GaN substrate from the interface between them.

(3) When such a contact layer is not provided and the cladding layer closer to the substrate has a lower refractive index than the substrate, the interface between the cladding layer and the substrate is directed toward the lower surface of the substrate. A metal mask is arranged at a position within half the thickness of the substrate. For example, AlG on a GaN thick film (substrate)
In the case of having an aN cladding layer, Ga
A metal mask is arranged at a position within half the thickness of the N thick film.

The reason for this is that if the metal mask is not formed within the above range, the area where the leaked light remains is wider than the area where the leaked light is absorbed by the metal mask, and the area is vertical This is because the single mode of the transverse mode is prevented. According to the findings of the present inventors, the shorter the distance from the interface to the metallic mask, the easier it was to obtain a single vertical transverse mode. This is because the AlGaN cladding layer and the GaN
When the distance from the interface with the contact layer to the metallic mask is increased, the vertical transverse mode light leaked into the GaN contact layer is reduced below the metallic mask, but the distance from the interface to the metallic mask is reduced. This is because the leakage light is not sufficiently reduced, so that a sub-peak due to the vertical / lateral mode light is observed, and the single vertical / lateral mode is not formed. Further, a metallic mask may be formed on or in the n-type AlGaN cladding layer 103. However, the active layer 105 and the n-type Ga
When formed at a position of less than 0.5 μm from the interface with the N light guide layer 104 (the lower surface of the active layer 105) toward the substrate 100, gain loss in laser oscillation increases due to the light absorption effect of the metallic mask, This causes an increase in the laser oscillation threshold current density. Therefore, the metallic mask is changed to n
Type AlGaN cladding layer 103 and its cladding layer 10
3, at least the active layer 105 and n
It is preferably formed at a position of 0.5 μm or more from the interface with the type GaN light guide layer 104 toward the substrate 100.

Further, as will be described later in detail in a ninth embodiment, when a metallic mask is provided on a nitride semiconductor film containing Al, a metal mask is provided on a GaN film not containing Al. Thus, the lateral growth rate in the selective growth is high, and the defect density is low. Further, a metallic mask may be formed so as to extend over an interface between the AlGaN cladding layer and the GaN contact layer or an interface between the AlGaN cladding layer and the GaN substrate. Further, when a semiconductor laser device is manufactured using a GaN substrate, since light leaking from the AlGaN cladding layer particularly hinders the formation of a single peak in the vertical / transverse mode, it is preferable to provide a metallic mask as described above. , A very high effect can be obtained.

On the other hand, regarding the direction parallel to the substrate,
Striped p-type electrode 112 (ridge stripe portion)
Is formed so that the metal mask is located below the metal mask. Further, it is preferable that the width (M) of the metallic mask is equal to or wider than the p-type electrode width Wp. The reason for this is to sufficiently absorb the leaked vertical mode light (FFP).

Further, the stripe direction of the metallic mask is aligned with the underlying nitride semiconductor layer (the lower layer G in this embodiment).
It is preferable to set the orientation in the <1-100> direction with respect to the aN film 102a) because lateral growth of the nitride semiconductor layer on the mask becomes faster and the coating speed becomes faster, and a flat coating film can be obtained.

In the present embodiment, tungsten (W) is used as a metallic mask having a light absorbing function in addition to the growth suppressing effect.
Metals such as Mo, Ni, Al, Pd, and Au, alloys thereof, and a composite film including a plurality of layers including them can be used. The nitride semiconductor does not greatly depend on the material as long as it is a metal that has a growth suppressing effect without direct epitaxial growth and has a light absorbing effect of absorbing laser light leaked from the cladding layer.

Further, in consideration of the light absorption effect, the thickness of the metallic mask is preferably about 0.01 μm or more, as will be described later in detail in Embodiment 8. Although depending on the shape of the mask, the thickness of the metallic mask is preferably 2 μm or less in consideration of the thickness of the nitride semiconductor film to be regrown and the flatness of the coating film.

With respect to the nitrogen carrier gas used for the selective growth, the partial pressure of the nitrogen carrier gas (N ₂ / (H ₂ +
N ₂ )) is preferably set to 0.1 (10% or more).
However, when the partial pressure of the nitrogen carrier gas exceeds 0.9, the half value width by X-ray diffraction exceeds 6 minutes, as will be described in detail in a ninth embodiment to be described later. The orientation of the compound deteriorates.

In this embodiment, the semiconductor laser device having the ridge stripe structure is described, but a stripe structure as described in Embodiments 3 to 7 described later may be used.

Further, in this embodiment, an example in which a GaN film is used as the low-temperature buffer layer 101 has been described.
Al _x Ga _1-x N (0 ≦ x ≦ 1) as low temperature buffer layer
There is no problem with using. In this embodiment, the crystal is grown in the order of the n-type layer, the active layer, and the p-type layer from the substrate side. However, the crystal may be grown in the order of the p-type layer, the active layer, and the n-type layer. This is the same in the following embodiments.

(Embodiment 2) In this embodiment, a nitride semiconductor laser device having the same configuration as that of Embodiment 1 except that an insulating film is provided on the metallic mask of Embodiment 1 will be described.

FIG. 3 shows the structure of the nitride semiconductor laser device of this embodiment. This nitride semiconductor laser device has a low-temperature GaN buffer layer 301 on a sapphire substrate 300,
n-type GaN contact layer 302, n-type Al _0.1 Ga _0.9 N
The clad layer 303, the n-type GaN light guide layer 304, and the active layer 305 (for example, three periods of In _0.18 Ga _0.82 N layer and I
n _0.05 Ga _0.95 N multiple quantum well active layer), A
l _0.2 Ga _0.8 N carrier block layer 306, p-type GaN
Light guide layer 307, p-type Al _0.1 Ga _0.9 N clad layer 3
08 and a p-type GaN contact layer 309 are sequentially stacked. The p-type cladding layer 308 is the p-type light guide layer 30
7, a ridge stripe portion composed of a p-type contact layer 309 and a p-type cladding layer 308 is formed. An insulating film 310 made of SiO ₂ is provided thereon, and the upper part of the ridge stripe is opened. A p-type electrode 312 is provided over the insulating film 310 and over the ridge stripe portion exposed from the opening of the insulating film 310, and the portion on the ridge stripe functions as a stripe electrode. On the other hand, portions from the p-type contact layer 308 to the n-type contact layer 302 are partially removed so that the surface of the n-type contact layer 302 is exposed, and an n-type electrode 311 is formed on the exposed portion of the n-type contact layer 302. ing.

The n-type contact layer 302 is a lower n-type Ga
The regrown film 302b covers the metal mask 315 with an insulating film, which is composed of the N film 302a and the regrown n-type GaN film 302b and is provided on the lower film 302a below the ridge stripe portion. The mask 315 includes a tungsten film 313 and an insulating film 314 made of SiO ₂ provided thereon.

The nitride semiconductor laser device of this embodiment can be manufactured, for example, as follows. First, as in the first embodiment, the sapphire substrate 3
Then, a low-temperature GaN buffer layer 301 is grown on
A μm lower n-type GaN film 302a is grown.

Next, the substrate was once taken out of the crystal growing apparatus, and the thickness was reduced to 0. 0 by an EB evaporation method or a sputtering method.
1 μm tungsten film and 0.05 μm thick SiO ₂
A film is formed on the n-type GaN film 302a. The tungsten film and the SiO ₂ film are formed on the lower nitride semiconductor film (GaN film 102) using a normal photolithography technique.
a) is formed in a stripe shape in the <1-100> direction with respect to a), and has a mask width (M) of 4 μm and a mask thickness of 0.15 μm
Thus, a stripe-shaped mask 315 composed of a tungsten film 313 and a SiO ₂ film 314 was arranged below a ridge stripe portion to be formed in a later step. Next, the substrate is placed in the crystal growth apparatus again, and an n-type GaN film 302b having a thickness of 1.5 μm is re-grown under the same conditions as in the first embodiment to obtain an n-type GaN contact layer 302.

Subsequently, under the same growth conditions as in the first embodiment,
n-type Al _0.1 Ga _0.9 N clad layer 303, n-type GaN light guide layer 304, active layer 305, Al _0.15 Ga _0.85 N carrier block layer 306, p-type GaN light guide layer 30
7, p-type Al _0.15 Ga _0.85 N cladding layer 308 and p
A type GaN contact layer 309 is grown. After that, the substrate is taken out of the crystal growth apparatus, and the semiconductor laser device having the ridge stripe structure shown in FIG. 3 is manufactured through the same semiconductor laser device manufacturing process as in the first embodiment.

N obtained by such a selective growth process
The surface of the type GaN contact layer 302 was flat and had no cracks. In the present embodiment, n
Insulating film (Si) provided in the p-type GaN contact layer 302
The presence of the tansguten mask 315 with an O ₂ film reduced the dislocation density by more than two orders of magnitude in each film constituting the laser structure after regrowth on the mask.
Further, the life characteristic of the semiconductor laser device itself is about 1200
It was 0 hours.

When the FFP in the vertical / lateral mode was observed for this nitride semiconductor laser device, it was found that the laser oscillated in a single-peak single mode. Further, the nitride semiconductor laser device of the present embodiment was subjected to a life test of 10,000 hours, and the vertical transverse mode was observed again. As a result, a stable single vertical transverse mode similar to the above was observed.

The reason is that, as in the first embodiment, the substrate 3
This is because the vertical transverse mode light leaked between 00 and the n-type AlGaN cladding layer 303 was absorbed by the tungsten mask 313 of the tungsten mask 315 with the insulating film. As a result, in the nitride semiconductor laser device of the present embodiment, as shown in FIG. 16A and FIG.
In addition, it is considered that a single vertical transverse mode that was stable was observed even after a life test of 10,000 hours, in addition to the effect of reducing the dislocation density due to the selective growth.

The difference between the second embodiment and the first embodiment is that the SiO ₂ film 314 is provided on the tungsten mask 313 so that the mask can be selectively grown on the GaN film as will be described later in a ninth embodiment. That is, the direction dependency of the pattern was reduced, and a sufficient lateral growth rate could be obtained. Generally, in the selective growth of a GaN film using a metal mask such as a tungsten mask, the mask has a strong dependence on the stripe direction.
Lateral growth (growth in the direction parallel to the substrate surface) is unlikely to occur. Therefore, by improving the lateral growth rate, the distance from the interface between the n-type AlGaN cladding layer 303 and the n-type GaN contact layer 302 to the tungsten mask 313 with the SiO ₂ film is reduced, and the tungsten mask 315 with the SiO ₂ film is reduced. The width (M) can be increased. As a result, a more stable single vertical / transverse mode than in the first embodiment could be obtained.

The metal mask with insulating film (S
The formation positions of the mask necessary for obtaining a single vertical transverse mode of the semiconductor laser device by the light absorption effect of the tungsten mask with an iO ₂ film) are different from those of the first embodiment in the vertical direction and the horizontal direction with respect to the substrate. The same is true. However, the formation position of the mask in this case refers to the formation position of the metal mask constituting the metal mask with the insulating film, and is the same as the first embodiment in this meaning.

In the present embodiment, tungsten (W) is used as a metallic mask having a light absorbing function in addition to the growth suppressing effect.
Metals such as Mo, Ni, Al, Pd, and Au, alloys thereof, and a composite film including a plurality of layers including them can be used. The nitride semiconductor does not greatly depend on the material as long as it is a metal that has a growth suppressing effect without direct epitaxial growth and has a light absorbing effect of absorbing laser light leaked from the cladding layer. As the insulating film provided immediately above the metallic mask, a SiN _x film may be used instead of the SiO ₂ film, and the insulating film does not largely depend on the material. Further, the thickness of the metal film constituting the metal mask with the insulating film is about 0.01 in consideration of the light absorption effect, as in the first embodiment.
It is preferably at least μm. In consideration of the thickness of the nitride semiconductor film to be regrown and the flatness of the coating film, the thickness of the entire mask including the metal film and the insulating film is preferably 2 μm or less. Further, the thickness of the insulating film is preferably 1 μm or less. This is because if the thickness of the insulating film exceeds 1 μm, the insulating film may be separated due to a difference in thermal expansion coefficient between the lower metal film and the insulating film.

The nitrogen carrier gas used in the selective growth is the same as in the first embodiment.

Further, in this embodiment, the semiconductor laser device having the ridge stripe structure is shown, but a stripe structure as shown in Embodiments 3 to 7 described later may be used.

(Embodiment 3) In Embodiment 3, an example will be described in which a metal mask for confining light in the horizontal and lateral modes is provided below the active layer.

FIG. 4 shows a nitride semiconductor laser device according to this embodiment.
This shows the structure of the child. This semiconductor laser device is an n-type GaN
On a substrate 401, n-type Al_0.02Ga_0.98N contact layer
402, n-type Al_0.1Ga_0.9N cladding layer 403, n-type
The GaN light guide layer 404, the active layer 405 (for example,
nm of In_0.15Ga_0.85N layer and 4 nm thick In_0.02G
a_0.98Multiple quantum well active layer consisting of N layers, thickness of 3 periods
4nm In_0.15Ga _0.85N layer and 10 nm thick In
_0.01Ga_0.99N-layer multiple quantum well active layer or 3 periods
In_0.18Ga_0.82N layer and In_0.05Ga_0.95From the N layer
Multiple quantum well active layer), Al_0.2Ga_0.8N carrier
Block layer 406, p-type GaN light guide layer 407, p-type
Al_0.1Ga_0.9N cladding layer 408 and p-type GaN core
Contact layers 409 are sequentially stacked. p-type contactor
A stripe-shaped portion serving as a current path is formed on the
Opened SiO_TwoProvided with an insulating film 410 made of
P-type over the opening and the insulating film 410.
An electrode 412 is provided on the opening of the insulating film 410.
The portion functions as a striped electrode. Also, n
N-type electrode 41 so as to be in contact with the back of
1 is formed.

N-type Al _0.1 Ga _0.9 N clad layer 403
Consists of a lower n-type Al _0.1 Ga _0.9 N film 403a and a regrown n-type Al _0.1 Ga _0.9 N cladding film 403b, and is provided with a metallic mask (tungsten mask) provided on the lower film 403a below the stripe-shaped electrode. 416 is covered with a regrown film 403b.

This semiconductor laser device can be manufactured, for example, as follows. First, while doping Si on the sapphire substrate by the HVPE method, a thick film G is formed.
aN is laminated, and then the sapphire substrate is peeled off by polishing to produce an n-type GaN substrate 401 having a thickness of 250 μm. The n-type GaN substrate 401 is set in a MOCVD apparatus, and an n-type Al _0.02 Ga _0.98 N contact layer 402 having a thickness of 5 μm is grown. After the growth of the n-type contact layer 402, the TMG is continuously grown at a growth temperature of 1050 ° C.
μmol / min, 10 nmol / mi of SiH ₄ gas
n and TMA are supplied at a flow rate of 10 μmol / min to grow a lower n-type Al _0.1 Ga _0.9 N film 403 a of 0.2 μm in the n-type cladding layer 403.

Next, the substrate is once taken out of the crystal growing apparatus.
And a tungsten film having a thickness of about 0.1 μm
Form a film. As a method of forming this tungsten film,
May use a sputtering method other than the EB evaporation method.
No. This tungsten film is used for normal photolithography
-Mask width 5μm, mask interval (S) 3μ
m in the form of stripes and the lower n-type Al_0.1G
a_0.9The N film 403a is exposed. At this time, tongues
The ten mask 416 is connected to the lower nitride semiconductor in the stripe direction.
Body layer (Al_0.1Ga_0.9<1-1 with respect to the N film 403a)
00> direction, and a stripe shape produced in a later step
It is covered with a tungsten mask 416 below the electrode.
The missing part 417 was arranged. Next, crystal growth of the substrate again
After installing in the equipment and replacing the atmosphere with nitrogen gas,
10 l / min of hydrogen, 5 l / min of hydrogen and ammonia
Temperature was raised to 1050 ° C while flowing 3 l / min
When the temperature becomes stable, TMG is added at 50 μmol / mi.
n and SiH_FourGas at 10 nmol / min and TMA
Is supplied at 10 μmol / min and the thickness of the n-type is 0.3 μm.
Al _0.1Ga_0.9The N film 403b is grown again. Growth progresses
The tungsten mask 416
No Al from part 417_0.1Ga_0.9N begins to grow again,
Lateral growth occurs to cover tungsten mask 416
Was. This laterally grown Al_0.1Ga_0.9N film 403b
Are completely bonded, and a flat surface cladding layer 403 is obtained.
Was.

After the lateral growth, the supply of TMA is stopped, and then an n-type GaN optical guide layer 404 having a thickness of 0.1 μm is grown. Next, under the same conditions as in the first embodiment,
Active layer 405, Al _0.15 Ga _0.85 N carrier block layer 406, p-type GaN optical guide layer 407, p-type Al _0.15 G
a _0.85 N cladding layer 408 and p-type GaN contact layer 409 are grown. After that, the substrate is taken out of the crystal growing apparatus, and a nitride semiconductor laser device of the present embodiment shown in FIG. 4 is manufactured through a semiconductor laser device manufacturing process.

N obtained by such a selective growth step
The surface of the mold Al _0.1 Ga _0.9 N cladding layer 403 was flat and had no cracks. Further, when observed by a transmission electron microscope, dislocations (crystal defects) were hardly observed in the Al _0.1 Ga _0.9 N film 403b coated on the tungsten mask 416. On the other hand, in the portion 417 not covered with the tungsten mask 416, the screw dislocations and the edge dislocations were bent on the tungsten mask 416 and disappeared while canceling each other. The dislocation density observed here was extremely low as compared with the case where a sapphire substrate was used. Further, the n-type A in the present embodiment
In the selective growth of the l _0.1 Ga _0.9 N film, the lateral growth can be accelerated as compared with the selective growth of the GaN film, as will be described later in detail in a ninth embodiment.

In the nitride semiconductor laser device of this embodiment, regrowth is performed on the GaN substrate and the AlGaN cladding layer due to the presence of the metallic mask (tungsten mask 416) having a growth suppressing effect provided in the AlGaN cladding layer. The dislocation density was about 10 ⁴ / cm ² in each of the films constituting the laser structure after the operation. As a result, the life characteristics of the semiconductor laser device itself were improved to about 20,000 hours.

The laser oscillation threshold current density of the nitride semiconductor laser device of this embodiment was measured.
5 is reduced to about 2/3 of the conventional ridge stripe structure semiconductor laser device. Further, when the horizontal and transverse modes were observed, laser oscillation was obtained in a single-peak single mode. Further, the nitride semiconductor laser device of this embodiment was subjected to a life test of 12,000 hours, and the horizontal transverse mode was observed again. As a result, a stable single horizontal transverse mode similar to the above was observed.

The following are conceivable reasons why the laser oscillation in the horizontal and lateral modes was obtained with the low threshold current value as described above. Since the tungsten mask 416 used in the present embodiment absorbed the laser light emitted from the active layer 405, the difference in the equivalent refractive index of the light guide layer between where the tungsten mask 416 was provided and where it was not provided. Occurs. Then, the tungsten mask 41
It is considered that the light confinement in the horizontal and transverse modes became conspicuous above the portion 417 not covered with 6, and a refractive index waveguide structure was obtained, which contributed to the reduction of the laser oscillation threshold current density. Further, in addition to this refractive index waveguide structure, gain loss is large above the mask due to strong light absorption by the metallic mask 416, and high-order transverse modes are hardly generated.
As a result, it is considered that a stable single horizontal transverse mode was observed.

In order to obtain the refractive index waveguide structure using the metallic mask (tungsten mask), the metallic mask is formed at the following positions in the vertical and horizontal directions with respect to the substrate. Is preferred.

First, with respect to the direction perpendicular to the substrate,
It is preferably formed at a position within 2 μm from the interface between the active layer 405 and the n-type light guide layer 404 (the lower surface of the active layer) toward the substrate. In this embodiment, 0.3 μm from the interface
The reason for this is that the tungsten mask 416 having a thickness of 0.1 μm is formed at the position of.
If the thickness exceeds μm, a difference in equivalent refractive index hardly occurs between the place where the metallic mask is provided and the place where the metallic mask is not provided, and the light confinement in the horizontal / lateral mode is weakened. According to the findings of the present inventors, the shorter the distance from the interface to the metallic mask, the larger the difference in the refractive index, and the stronger the light confinement effect in the horizontal and transverse modes.

On the other hand, regarding the direction parallel to the substrate,
It is formed so that a portion 417 not covered with a metal mask is located below the stripe-shaped p-type electrode 412. Further, the distance (S) between the metallic masks is preferably 15 μm or less. The reason is as follows.

The effective refractive index n ₁ of the light guide layer where the tungsten mask 416 is provided, the effective refractive index n ₂ of the light guide layer where the tungsten mask 416 is not provided, the wave number of light in vacuum Is approximately ₀ , and the pi is π, and approximately using the equivalent refractive index method, the mask interval (S) of the metallic mask is S <π / (k ₀ is required to be ^{_{(n 22 -n 12) 1/2)}} . Therefore, when a metallic mask is formed at a position 2 μm from the interface where the refractive index difference is the smallest, the mask interval (S) is 15 μm or less according to the above equation. However, the upper limit of the appropriate mask interval (S) (horizontal position) is not uniquely determined by the vertical position of the mask. This is because if the mask interval (S) is too narrow, gain loss occurs due to light absorption by the metallic mask, and the laser oscillation threshold current density increases. In such a case, it is preferable to set the mask interval (S) larger than the value calculated by the equivalent refractive index method. According to the experiments performed by the inventors of the present application, it is preferable that the mask interval (S) is formed to be 1 μm or more and 15 μm or less.

In this embodiment, tungsten (W) is used as a metallic mask having a light absorbing function in addition to a growth suppressing effect.
Metals such as Mo, Ni, Al, Pd, and Au, alloys thereof, and a composite film including a plurality of layers including them can be used. If the nitride semiconductor is a metal having a light absorption effect of absorbing the laser light emitted from the active layer, the growth suppression effect is obtained without direct epitaxial growth,
There is no significant dependence on the material. Further, the thickness of the metallic mask depends on the shape of the mask, but is preferably 0.01 μm or more in consideration of the light absorption effect. In consideration of the properties, the thickness is preferably 2 μm or less.

In the present embodiment, the metallic mask 416 is replaced by n
Although the metal mask 416 is not completely buried in the n-type AlGaN cladding layer 403, the net laser element part is striped p-type. This is because the electrode 412 is formed over the entire lower portion (column portion) of the width (Wp) of the electrode 412. Therefore, in the n-type AlGaN cladding layer 403, it is sufficient that at least the mask interval (S) portion is crystal-grown. However, if the mask portion is not completely buried, the flatness of the p-type GaN contact layer 409 is poor, and it is difficult to form a p-type electrode, which may lower the yield of the laser device structure.

As for the nitrogen carrier gas used in the selective growth, the partial pressure of the nitrogen carrier gas with respect to the total carrier gas is set to 0.1 (10
% Or more). However, when the partial pressure of the nitrogen carrier gas exceeds 0.9, the half-value width by X-ray diffraction exceeds 6 minutes, as shown in Embodiment 9 described below.
The crystal orientation in the coated nitride semiconductor film deteriorates.

By the way, in the conventional ridge stripe structure, in order to obtain a refractive index waveguide structure, as shown in FIG. It was difficult to control the layer thickness, and it was difficult to obtain reproducibility in the horizontal and transverse modes. In addition, deterioration occurs at the exposed end face due to the formation of the ridge stripe portion, and the laser oscillation threshold current density increases.
This had an adverse effect on the characteristics of the laser element. For this reason, in consideration of productivity, the conventional ridge stripe structure has a problem that the yield rate is low. On the other hand, according to the present embodiment, it is possible to easily manufacture a metallic mask using the conventional lithography technique, there is no exposure of the end face such as the ridge stripe structure, and the thickness of the cladding layer is reduced. Since the growth can be controlled, the yield can be increased as compared with the ridge stripe structure.

In the case of the ridge stripe structure,
Although such an effect of improving the yield cannot be obtained, by providing a metallic mask as in the present embodiment, the effect of light confinement by the metal film and the effect of reducing the dislocation density of the grown layer thereon by the material film which does not epitaxially grow are provided. Is obtained. Further, by providing the metallic mask with the insulating film, a current confinement effect by both the insulating film and the ridge can be obtained.

In the present embodiment, the Al composition of the cladding layer to be regrown is set to 0.1. However, the same effect can be obtained with a nitride semiconductor having a composition of 0 <Al ≦ 1.

(Embodiment 4) In this embodiment, a structure provided by combining the metal mask with an insulating film of Embodiment 2 and the metal mask of Embodiment 3 will be described.

FIG. 5 shows the structure of the nitride semiconductor laser device of this embodiment. This semiconductor laser device has a low-temperature GaN buffer layer 501, an n-type GaN contact layer 502, an n-type Al _0.1 Ga _0.9 N clad layer 503, an n-type GaN light guide layer 504, and an active layer 5 on a sapphire substrate 500.
05 (for example, a multiple quantum well active layer composed of a 2 nm thick In _0.15 Ga _0.85 N layer and a 4 nm thick In _0.02 Ga _0.98 N layer, three periods of a 4 nm thick In _0.15 Ga _0.85 N layer and a 10 nm thick A multiple quantum well active layer composed of an In _0.01 Ga _0.99 N layer, a three-period In _0.18 Ga _0.82 N layer and an In _0.05 G
a _0.95 N quantum well active layer etc.), Al _0.2
Ga _0.8 N carrier block layer 506, p-type GaN optical guide layer 507, p-type Al _0.1 Ga _0.9 N cladding layer 508
And a p-type GaN contact layer 509 are sequentially stacked. On the p-type contact layer 509, there is provided an insulating film 510 made of SiO ₂ having an opening in a striped portion serving as a current path, and the opening and the insulating film 510 are provided.
A p-type electrode 512 is provided over the insulating film 5.
The portion above the opening 10 functions as a striped electrode. The p-type contact layer 509 to the n-type contact layer 502 are partially removed so that the surface of the n-type contact layer 502 is exposed.
An n-type electrode 511 is formed on the exposed part of the above.

The n-type contact layer 502 is a lower n-type Ga
The regrown film 502b covers the metal mask 515 with an insulating film, which is composed of the N film 502a and the regrown n-type GaN film 502b and is provided on the lower film 502a below the stripe electrode. The mask 515 includes a tungsten film 513 and an insulating film 514 made of SiO ₂ provided thereon. n-type Al _0.1 Ga
_{The 0.9} N cladding layer 503 is a lower n-type Al _0.1 Ga _0.9 N
Film 503a and regrown n-type Al _0.1 Ga _0.9 N clad film 5
03b, the lower film 5 below the stripe-shaped electrode
The metal mask (tungsten mask) 516 provided on the upper portion 03a is covered with a regrowth film 503b.

The nitride semiconductor laser device of this embodiment can be manufactured, for example, as follows. First, as in the second embodiment, the sapphire substrate 5
A low-temperature GaN buffer layer 501 is grown on the N-type GaN buffer layer
A lower n-type GaN film 502a of m is grown.

Next, as in the second embodiment, the underlying GaN
A metal mask 515 with an insulating film having a mask width (M) of 5 μm and a mask thickness of 0.15 μm is formed in a stripe shape in the <1-100> direction on the film 502a. The mask 515 is composed of a tungsten film 513 having a thickness of 0.1 μm and a SiO ₂ film 514 having a thickness of 0.05 μm, and is arranged below a stripe-shaped electrode to be formed in a later step. Next, the substrate is placed in the crystal growth apparatus again, and the n-type GaN film 502b having a thickness of 2 μm is formed as in the second embodiment.
Is regrown to form a flat and crack-free n-type GaN contact layer 502.

Subsequently, as in the third embodiment, a thickness of 0.2
A μm lower Al _0.1 Ga _0.9 N film 503 a is grown. Next, the substrate was once taken out of the crystal growth apparatus, and
Similarly, a mask width of 5 μm is formed on the lower Al _0.1 Ga _0.9 N film 503a in a stripe shape in the <1-100> direction.
A tungsten mask 516 having a thickness of about 0.1 μm and a mask interval (S) of 3 μm is formed. At this time, a portion 517 not covered with the tungsten mask 516 is arranged below the stripe-shaped electrode to be formed in a later step.

Next, the substrate was placed in the crystal growth apparatus again, and an n-type Al
_{The 0.1} Ga _0.9 N film 503b is grown again. As the growth progressed, Al _0.1 Ga _0.9 N began to regrow from the portion 517 not covered by the tungsten mask 516, and lateral growth occurred, covering the tungsten mask 516. This laterally grown Al _0.1 Ga _0.9 N film 503b was completely bonded, and a flat surface clad layer 503 was obtained.

Subsequently, as in Embodiment 3, n-type GaN
Light guide layer 504, active layer 505, Al _0.15 Ga _0.85 N
Carrier block layer 506, p-type GaN optical guide layer 50
7, p-type Al _0.15 Ga _0.85 N cladding layer 508 and p-type
A type GaN contact layer 509 is grown. Thereafter, the substrate is taken out of the crystal growing apparatus, and a nitride semiconductor laser device of the present embodiment shown in FIG. 5 is manufactured through a semiconductor laser device manufacturing process.

N obtained by such a selective growth step
-Type GaN contact layer 502 and n-type Al _0.1 Ga _0.9
The surface of the N cladding layer 503 was flat and no crack was generated. In the n-type GaN contact layer 502, dislocations (crystal defects) generated from the interface between the substrate 500 and the low-temperature GaN buffer layer 501 were reduced as in the second embodiment. On the other hand, when the n-type Al _0.1 Ga _0.9 N cladding layer 503 was observed by a transmission electron microscope, dislocations (crystal defects) were hardly observed in the Al _0.1 Ga _0.9 N film 503 b coated on the tungsten mask 516. In the portion 517 not covered with the tungsten mask 516, the screw dislocations and the edge dislocations were bent on the tungsten mask 516 and disappeared while canceling each other. Further, the n-type Al in the present embodiment
_In the selective growth of the _0.1 Ga _0.9 N film, the lateral growth was faster than the selective growth of the GaN film, as will be described later in detail in a ninth embodiment.

Further, the nitride semiconductor laser device of the present embodiment has a structure in which the Si having a growth suppressing effect provided in the GaN contact layer 502 and the AlGaN cladding layer 503 is provided.
Due to the presence of the tungsten mask 515 with the O ₂ film and the tansguten mask 516, the dislocation density was reduced by two to three digits or more in each film constituting the laser structure after regrowth on the mask. As a result, the life characteristics of the semiconductor laser device itself were improved to about 17000 hours.

The laser oscillation threshold current density of the nitride semiconductor laser device of this embodiment was measured.
5 is reduced to about 2/3 of the conventional ridge stripe structure semiconductor laser device. In addition, when the modes of the horizontal and vertical modes and the NFP and FFP in the vertical and horizontal modes were observed, laser oscillation was obtained in a single mode with a single peak. Further, the nitride semiconductor laser device of the present embodiment was subjected to a life test of 10,000 hours, and the horizontal and horizontal modes and the vertical and horizontal modes were observed again. Mode and was observed.

The reason why the single-peak (single) and stable vertical / lateral mode laser oscillation is obtained is the same as in the first and second embodiments. Also, the formation position of the vertical / lateral mode, that is, the tungsten mask 5 with the SiO ₂ film
The formation position of 15 is the same as that of the second embodiment in each of a direction perpendicular to and parallel to the substrate. further,
The reason why stable single-peak (single) horizontal and transverse mode laser oscillation is obtained is the same as in the third embodiment. The formation position of the horizontal / lateral mode, that is, the formation position of the tungsten film 516 is the same as that of the third embodiment in each of the vertical direction and the parallel direction with respect to the substrate.

In the present embodiment, tungsten (W) is used as the metal mask in the metal mask 515 with the insulating film and the metal mask 516. In addition, for example, Pt, Ti, Mo, Ni, Al , Pd, Au
Or a metal alloy thereof, or a composite film composed of a plurality of layers containing them. The growth suppression effect is obtained without direct epitaxial growth of the nitride semiconductor,
As long as the metal has a light absorbing effect of absorbing the laser light emitted from the active layer, it does not largely depend on the material. Further, in the metal mask 515 with an insulating film, an SiN _x film may be used as the insulating film other than the SiO ₂ film, and the insulating film does not largely depend on the material. Furthermore, a metallic mask 515 with an insulating film
The thickness of the metallic mask 516 is the same as in the second and third embodiments. However, the metal mask 516 does not need to be completely buried in the cladding layer, as in the third embodiment. The nitrogen carrier gas used in the selective growth is also the same as in the second and third embodiments.

According to the semiconductor laser device of this embodiment,
The same effects as those of the second and third embodiments can be obtained.
In this embodiment, the metallic mask with the insulating film is formed in the n-type GaN contact layer. However, a metallic mask may be formed. When a metal mask is formed, the same effects as in the first embodiment can be obtained.

In this embodiment, G is used as the low-temperature buffer layer.
Although the example using the aN film has been described, no problem occurs even if Al _x Ga ₁ -xN (0 ≦ x ≦ 1) is used as the low-temperature buffer layer. Further, in the present embodiment, the Al composition of the cladding layer to be regrown is set to 0.1, but 0 <Al ≦ 1.
A similar effect can be obtained with a nitride semiconductor having the following composition.

(Embodiment 5) In this embodiment, a structure in which a metal mask with an insulating film is provided in the AlGaN cladding layer in place of the metal mask in Embodiment 4 will be described.

FIG. 6 shows the structure of the nitride semiconductor laser device of this embodiment. This semiconductor laser device includes a low-temperature GaN buffer layer 601, an n-type GaN contact layer 602, an n-type Al _0.1 Ga _0.9 N clad layer 603, an n-type GaN light guide layer 604, and an active layer 6 on a sapphire substrate 600.
05 (for example, a multiple quantum well active layer composed of a 2 nm thick In _0.15 Ga _0.85 N layer and a 4 nm thick In _0.02 Ga _0.98 N layer, three periods of a 4 nm thick In _0.15 Ga _0.85 N layer and a 10 nm thick A multiple quantum well active layer composed of an In _0.01 Ga _0.99 N layer, a three-period In _0.18 Ga _0.82 N layer and an In _0.05 G
a _0.95 N quantum well active layer etc.), Al _0.2
Ga _0.8 N carrier block layer 606, p-type GaN optical guide layer 607, p-type Al _0.1 Ga _0.9 N cladding layer 608
And a p-type GaN contact layer 609 are sequentially stacked. On the p-type contact layer 609, an insulating film 610 made of SiO ₂ having a stripe-shaped portion serving as a current path is provided, and the opening and the insulating film 610 are provided.
A p-type electrode 612 is provided over the insulating film 61.
The portion above the opening of the zero functions as a stripe-shaped electrode. From the p-type contact layer 609 to the n-type contact layer 6
Until 02, the surface of the n-type contact layer 602 is partially removed so as to be exposed. On the exposed portion of the n-type contact 602, an n-type electrode 611 is formed.

The n-type contact layer 602 is a lower n-type Ga
The regrown film 602b covers the metal mask 615 with an insulating film, which is composed of the N film 602a and the regrown n-type GaN film 602b and is provided on the lower film 602a below the stripe-shaped electrode. This mask 615 includes a tungsten film 613 and an insulating film 614 made of SiO ₂ provided thereon. n-type Al _0.1 Ga
_{The 0.9} N cladding layer 603 is a lower n-type Al _0.1 Ga _0.9 N
Film 603a and regrown n-type Al _0.1 Ga _0.9 N clad film 6
03b, the lower film 6 below the stripe-shaped electrode.
Metallic mask 6 with insulating film provided on upper portion 03a
18 is covered with a regrowth film 603b. This mask 618 is composed of a tungsten film 616 and an insulating film 617 made of SiO ₂ provided thereon.

The nitride semiconductor laser device of this embodiment can be manufactured, for example, as follows. First, as in the second embodiment, the sapphire substrate 6
A low-temperature GaN buffer layer 601 is grown on the GaN buffer layer
A μm lower n-type GaN film 602a is grown.

Next, as in the second embodiment, the lower GaN
A metal mask 615 with an insulating film having a mask width (M) of 5 μm and a mask thickness of 0.15 μm is formed in a stripe shape in the <1-100> direction on the film 602a. The mask 615 is composed of a tungsten film 613 having a thickness of 0.1 μm and a SiO ₂ film 614 having a thickness of 0.05 μm, and is arranged below a stripe-shaped electrode to be formed in a later step. Next, the substrate is placed in the crystal growth apparatus again, and the n-type GaN film 602 having a thickness of 10 μm is formed as in the second embodiment.
b is regrown to form a flat and crack-free n-type GaN contact layer 602. Here, an HVPE growth apparatus was used as the crystal growth apparatus.

Subsequently, as in the third embodiment, a thickness of 0.2
A μm lower Al _0.1 Ga _0.9 N film 603 a is grown. Thereafter, the substrate is once taken out of the crystal growth apparatus, and a tungsten film having a thickness of about 0.06 μm is formed by an EB evaporation method or a sputtering method.
Depthion method) about 0.04μm thick
To form a SiO ₂ film. Then, using a normal photolithography technique, the substrate is etched into a stripe shape with a mask width of 5 μm and a mask interval (S) of 2 μm to form a lower Al layer.
_{The 0.1} Ga _0.9 N film 603a is exposed. At this time, Si
The tungsten mask 618 with the O ₂ film has a stripe direction <1-10 with respect to the lower Al _0.1 Ga _0.9 N film 603a.
0> direction, and a portion 619 which is not covered with the tungsten mask 616 is arranged below the stripe-shaped electrode manufactured in a later step. Next, the substrate was placed in the crystal growth apparatus again, and the thickness was 0.2 μm as in the third embodiment.
The n-type Al _0.1 Ga _0.9 N film 603b is regrown. As the growth progresses, Al _0.1 Ga is removed from the portion 619 not covered with the tungsten mask 618 with the SiO ₂ film.
_0.9 N began to regrow and lateral growth occurred, covering the SiO ₂ -coated tungsten mask 618. The laterally grown Al _0.1 Ga _0.9 N film 603b is completely bonded,
The cladding layer 603 having a flat surface was obtained.

Subsequently, as in Embodiment 4, n-type GaN
Light guide layer 604, active layer 605, Al _0.15 Ga _0.85 N
Carrier block layer 606, p-type GaN light guide layer 60
7, p-type Al _0.15 Ga _0.85 N cladding layer 608 and p-type
A type GaN contact layer 609 is grown. After that, the substrate is taken out of the crystal growing apparatus, and a nitride semiconductor laser device of the present embodiment shown in FIG. 6 is manufactured through a semiconductor laser device manufacturing process.

The n obtained by such a selective growth step
-Type GaN contact layer 602 and n-type Al _0.1 Ga _0.9
The surface of the N clad layer 603 was flat and no crack was generated. Dislocations related to n-type GaN contact layer 602 and n-type AlGaN cladding layer 603 (crystal defects)
Decreased as in the fourth embodiment. Further, the nitride semiconductor laser device of the present embodiment has the GaN contact layer 6
02 and the AlGaN cladding layer 603, the presence of the SiO ₂ film-provided tungsten masks 615 and 618 provided in the AlGaN cladding layer 603, cause each of the films constituting the laser structure to be regrown on the mask. The dislocation density decreased by two to three digits or more. As a result, the life characteristics of the semiconductor laser device itself were improved to about 17000 hours.

The laser oscillation threshold current density of the nitride semiconductor laser device of this embodiment was measured.
5 was reduced to about の of the conventional semiconductor laser device having the ridge stripe structure. In addition, when the modes of the horizontal and vertical modes and the NFP and FFP in the vertical and horizontal modes were observed, laser oscillation was obtained in a single mode with a single peak. Further, the nitride semiconductor laser device of the present embodiment was subjected to a life test of 10,000 hours, and the horizontal and horizontal modes and the vertical and horizontal modes were observed again. Mode and was observed.

The reason why the laser oscillation threshold current density is reduced as described above is as follows.

The metal mask 618 with an insulating film formed in the cladding layer 603 is formed of a metal mask (tungsten film 616) having a light absorbing effect and an insulating film (SiO 2 film).
₂ ), the refractive index waveguide structure obtained by the light trapping in the horizontal transverse mode due to the light absorption effect of the former, and the current confinement by covering the metallic mask with the insulating film of the latter. This is because carrier confinement has occurred. That is, by using the tungsten mask 618 with the SiO ₂ film, in addition to the laser characteristics by the refractive index waveguide structure described in the fourth embodiment, a current confinement structure can be simultaneously formed in the device.

The reason why a single-peak (single) and stable vertical / lateral mode laser oscillation is obtained is the same as in the first and second embodiments. Further, the formation position of the vertical / lateral mode, that is, the tungsten mask 61 with the SiO ₂ film
The formation position of 5 is the same as that of the second embodiment in each of a direction perpendicular to and parallel to the substrate. Further, the reason why a single-peak (single) and stable horizontal and transverse mode laser oscillation is obtained is the same as in the fourth embodiment. The formation position of the horizontal / lateral mode, that is, the formation position of the tungsten mask with SiO ₂ film 618 is the same as that of the fourth embodiment in each of the vertical direction and the parallel direction with respect to the substrate. However, the position of the metallic mask with an insulating film in this case refers to the formation position of the metallic mask constituting the metallic mask with an insulating film, and is the same as the fourth embodiment in this meaning. .

In the present embodiment, in addition to the current constriction effect,
Therefore, the following effects are also obtained. This embodiment is similar to the fourth embodiment.
In comparison, gold with an insulating film formed in the cladding layer 603
Lateral growth is faster due to attribute mask 618
You. The reason for this will be described in detail in Embodiment 9 described later.
As described above, the selective growth of the AlGaN film is the same as the selective growth of the GaN film.
Lateral growth is much faster than
SiO on the disk 616 _TwoBy providing the film 617,
This is because lateral growth becomes faster. This
From the interface between the active layer 605 and the n-type light guide layer 604.
The distance to the disc 618 is shortened, and the light
The jamming effect could be strengthened.

Further, as will be described in detail later in a ninth embodiment, in the selective growth of a GaN film using a metallic mask (tungsten mask), the mask generally has a strong dependence on the stripe direction, and lateral growth is difficult. However, by using a tungsten mask with an SiO ₂ film, sufficient lateral growth can be obtained even in the selective growth of a GaN film without directional dependence of the mask pattern. Utilizing this characteristic, a position within a range where a tungsten mask 618 with a SiO ₂ film can be formed in order to obtain a refractive index waveguide structure in a direction perpendicular to the substrate (a position within 2 μm from the upper or lower surface of the active layer). Even if a nitride semiconductor containing no Al exists in (1), selective growth at a high lateral growth rate can be achieved.

In the present embodiment, tungsten (W) is used as the metal mask in the metal masks 615 and 618 with the insulating film.
Metals such as t, Ti, Mo, Ni, Al, Pd, and Au and alloys thereof, or a composite film including a plurality of layers including them can be used. As long as the nitride semiconductor does not directly epitaxially grow and has a growth suppressing effect and has a light absorbing effect of absorbing a laser beam emitted from the active layer, the metal does not largely depend on the material. Further, in the metal masks 615 and 618 with an insulating film, an SiN _x film may be used as the insulating film other than the SiO ₂ film, and the insulating film does not largely depend on the material. When the metal mask is covered with the insulating film, it is preferable that the side portion 620 of the metal mask is also covered with the insulating film. Further, the thicknesses of the metal masks 615 and 618 with the insulating film, the nitrogen carrier gas used for selective growth, the yield, and the like are the same as in the fourth embodiment.

In this embodiment, the metallic mask with the insulating film is formed in the n-type GaN contact layer. However, a metallic mask may be formed. When a metal mask is formed, the same effects as in the first embodiment can be obtained. Further, the metal mask 618 with the insulating film is formed in the same manner as in the third embodiment.
It does not have to be completely buried in the cladding layer. However, in order to improve the yield rate in manufacturing a laser element, it is preferable that the metallic mask 618 with an insulating film be buried in the cladding layer.

In this embodiment, G is used as the low-temperature buffer layer.
Although the example using the aN film has been described, no problem occurs even if Al _x Ga ₁ -xN (0 ≦ x ≦ 1) is used as the low-temperature buffer layer. Further, in the present embodiment, the Al composition of the cladding layer to be regrown is set to 0.1, but 0 <Al ≦ 1.
A similar effect can be obtained with a nitride semiconductor having the following composition.

(Embodiment 6) In this embodiment, a structure in which a metal mask is provided in a p-type cladding layer instead of forming a metal mask in an n-type cladding layer in Embodiment 4 will be described.

FIG. 7 shows the structure of the nitride semiconductor laser device of this embodiment. This semiconductor laser device has a low-temperature GaN buffer layer 701, an n-type GaN contact layer 702, an n-type Al _0.1 Ga _0.9 N clad layer 703, an n-type GaN light guide layer 704, an active layer 7 on a sapphire substrate 700.
05 (for example, a multiple quantum well active layer composed of a 2 nm thick In _0.15 Ga _0.85 N layer and a 4 nm thick In _0.02 Ga _0.98 N layer, three periods of a 4 nm thick In _0.15 Ga _0.85 N layer and a 10 nm thick A multiple quantum well active layer composed of an In _0.01 Ga _0.99 N layer, a three-period In _0.18 Ga _0.82 N layer and an In _0.05 G
a _0.95 N quantum well active layer etc.), Al _0.2
Ga _0.8 N carrier block layer 706, p-type GaN optical guide layer 707, p-type Al _0.1 Ga _0.9 N cladding layer 708
And a p-type GaN contact layer 709 are sequentially stacked. On the p-type contact layer 709, there is provided an insulating film 710 made of SiO ₂ having an opening in a striped portion serving as a current path, and the opening and the insulating film 710 are provided.
A p-type electrode 712 is provided over the insulating film 7.
The portion above the opening 10 functions as a striped electrode. A portion from the p-type contact layer 709 to the n-type contact layer 702 is partially removed so that the surface of the n-type contact layer 702 is exposed.
An n-type electrode 711 is formed on the exposed part of the above.

The n-type contact layer 702 is a lower n-type Ga
The regrown film 702b covers the metal mask 715 with an insulating film, which is composed of the N film 702a and the regrown n-type GaN film 702b and is provided on the lower film 702a below the stripe-shaped electrode. This mask 715 includes a platinum film 713 and an insulating film 714 made of SiN _x provided thereon. The p-type Al _0.1 Ga _0.9 N cladding layer 708 is a lower p-type Al _0.1 Ga _0.9 N film 708 a
And a regrown p-type Al _0.1 Ga _0.9 N clad film 708b, and a metal mask 716 (platinum mask) provided on the lower film 708a below the stripe-shaped electrode is covered with the regrown film 708b. .

The nitride semiconductor laser device of this embodiment can be manufactured, for example, as follows. First, as in the second embodiment, the sapphire substrate 7
A low-temperature GaN buffer layer 701 is grown on the P.O.
A lower n-type GaN film 702a of m is grown.

Next, as in Embodiment 2, the lower GaN
A metal mask 715 with an insulating film having a mask width (M) of 5 μm and a mask thickness of 0.15 μm is formed in a stripe shape in the <1-100> direction on the film 702a. The mask 715 is composed of a platinum film 713 having a thickness of 0.1 μm and a SiN _x film 714 having a thickness of 0.05 μm, and is arranged below a stripe-shaped electrode to be formed in a later step. Next, the substrate was placed in the crystal growth apparatus again,
In the same manner as described above, the n-type GaN film 702b having a thickness of 20 μm is re-grown to obtain a flat and crack-free n-type GaN film 702b.
An aN contact layer 702 is formed.

Subsequently, as in Embodiment 2, n-type Al
_{A 0.1} Ga _0.9 N cladding layer 703, an n-type GaN light guide layer 704, an active layer 705, an Al _0.2 Ga _0.8 N carrier block layer 706, and a p-type GaN light guide layer 707 are grown.

Then, of the p-type contact layers 708,
A lower Al _0.1 Ga _0.9 N film 708a having a thickness of 0.15 μm is grown. Next, the substrate was once taken out of the crystal growing apparatus, and the lower Al _0.1 Ga _0.9 N film 708a was subjected to <1-1.
A platinum mask 716 having a mask width of 2.5 μm, a mask interval (S) of 2 μm, and a thickness of about 0.08 μm is formed in a stripe shape in the direction of the <00> direction. At this time, a portion 717 not covered with the platinum mask 716 is arranged below the stripe-shaped electrode to be formed in a later step. Next, the substrate was placed again in the crystal growth apparatus, and a 0.4 μm-thick p-type Al _0.1 G
The a _0.9 N film 708b is grown again. As the growth progresses, the portion 717 not covered with platinum 716
_0.1 Ga _0.9 N began to regrow and lateral growth occurred to cover the platinum mask 716. This laterally grown Al
_{The 0.1} Ga _0.9 N film 708 b was completely bonded, and the flat clad layer 708 was obtained.

Subsequently, a p-type GaN contact layer 709 is grown as in the fourth embodiment. After that, the substrate is taken out of the crystal growing apparatus, and a nitride semiconductor laser device of the present embodiment shown in FIG. 7 is manufactured through a semiconductor laser device manufacturing process.

The n obtained by such a selective growth step
-Type GaN contact layer 702 and p-type Al _0.1 Ga _0.9
The surface of the N-cladding layer 708 was flat and had no cracks. In the n-type GaN contact layer 702, dislocations (crystal defects) were reduced as in the first and second embodiments.

The nitride semiconductor laser device of this embodiment is
Due to the presence of the platinum mask 715 with a SiN _x film having a growth suppressing effect provided in the GaN contact layer 702, the dislocation density becomes 2 in each film constituting the laser structure after regrowth on the mask. It has decreased by an order of magnitude.
As a result, the life characteristics of the semiconductor laser device itself are about 120.
00 hours.

The laser oscillation threshold current density of the nitride semiconductor laser device of this embodiment was measured.
5 is reduced to about 2/3 of the conventional ridge stripe structure semiconductor laser device. In addition, when the modes of the horizontal and vertical modes and the NFP and FFP in the vertical and horizontal modes were observed, laser oscillation was obtained in a single mode with a single peak. Further, the nitride semiconductor laser device of the present embodiment was subjected to a life test of 10,000 hours, and the horizontal and horizontal modes and the vertical and horizontal modes were observed again. Mode and was observed.

The reason why the single-peak (single) and stable vertical / lateral mode laser oscillation is obtained is the same as in the first and second embodiments. The formation position of the vertical / lateral mode, that is, the formation position of the platinum mask with SiN _x film 715 is the same as that of the second embodiment in each of the vertical direction and the parallel direction with respect to the substrate. On the other hand, the reason why a single-peak (single) stable horizontal and transverse mode laser oscillation was obtained is that the platinum mask 716 used in this embodiment is the active layer 7.
Since the laser light emitted from the laser beam 05 is absorbed, a difference occurs in the equivalent refractive index of the light guide layer between the place where the platinum mask 716 is provided and the place where the platinum mask 716 is not provided. It is considered that the light confinement in the horizontal and transverse modes became conspicuous above the portion 717 not covered with the platinum mask 716, and a refractive index waveguide structure was obtained, which contributed to the reduction of the laser oscillation threshold current density. . In addition to the refractive index waveguide structure, gain loss is large above the mask due to strong light absorption by the metallic mask 716, and high-order transverse modes are less likely to occur. As a result, it is considered that a stable single horizontal transverse mode was observed.

The formation position of this horizontal / lateral mode, that is,
The platinum film 716 is preferably formed at the following positions in the direction perpendicular to and parallel to the substrate.

First, in the direction perpendicular to the substrate,
Active layer 705 and carrier block layer 706 (p-type light guide layer 705 if carrier block layer 706 is not provided)
Is preferably formed at a position within 2 μm from the interface (upper surface of the active layer) in the direction opposite to the substrate. In the present embodiment, a thickness of 0.0
An 8 μm platinum mask 716 is formed. The reason for this is that when the position of the metallic mask is more than 2 μm from the interface, there is almost no equivalent refractive index difference between the place where the metallic mask is provided and the place where the metallic mask is not provided. This is because light confinement is weakened. According to the findings of the present inventors, the shorter the distance from the interface to the metallic mask, the larger the difference in the refractive index, and the stronger the light confinement effect in the horizontal and transverse modes. Further, in the present embodiment, the active layer 705 and the carrier block layer 706 (p when no carrier block layer 706 is provided)
The distance from the interface of the shaped light guide layer 707) to the metallic mask can be set by the crystal growth speed of the crystal growth apparatus. Therefore, as compared with Embodiments 4 and 5, the distance from the interface to the mask can be controlled more accurately, and the light confinement effect in the horizontal and horizontal modes can be controlled more accurately.

On the other hand, regarding the direction parallel to the substrate,
A portion 717 not covered with a metal mask is formed below the p-type electrode 712 in a stripe shape. Further, similarly to the third embodiment, the interval (S) between the metallic masks is preferably 1 μm or more and 15 μm or less.

The thickness of the metallic mask 715 with insulating film and the metallic mask 716, the nitrogen carrier gas used for selective growth, the yield, and the like are the same as in the fourth embodiment.

In this embodiment, the metallic mask with the insulating film is formed in the n-type GaN contact layer. However, a metallic mask may be formed. When a metal mask is formed, the same effects as in the first embodiment can be obtained. Further, the metal mask 716 does not need to be completely buried in the cladding layer, as in the third embodiment. However, it is preferable that the metallic mask 716 with an insulating film be buried in the cladding layer in order to improve the yield rate of the laser element production.

In this embodiment, G is used as the low-temperature buffer layer.
Although the example using the aN film has been described, no problem occurs even if Al _x Ga ₁ -xN (0 ≦ x ≦ 1) is used as the low-temperature buffer layer. Further, in the present embodiment, the Al composition of the cladding layer to be regrown is set to 0.1, but 0 <Al ≦ 1.
A similar effect can be obtained with a nitride semiconductor having the following composition.

Furthermore, a synergistic effect can be obtained by combining this embodiment with the above-described fourth or fifth embodiment.

(Embodiment 7) In this embodiment, a structure in which a metal mask with an insulating film is provided in the AlGaN cladding layer in place of the metal mask in Embodiment 6 will be described.

FIG. 8 shows the structure of the nitride semiconductor laser device of this embodiment. This semiconductor laser device has a low-temperature GaN buffer layer 801, an n-type GaN contact layer 802, an n-type Al _0.1 Ga _0.9 N clad layer 803, an n-type GaN light guide layer 804, and an active layer 8 on a sapphire substrate 800.
05 (for example, a multiple quantum well active layer composed of a 2 nm thick In _0.15 Ga _0.85 N layer and a 4 nm thick In _0.02 Ga _0.98 N layer, three periods of a 4 nm thick In _0.15 Ga _0.85 N layer and a 10 nm thick A multiple quantum well active layer composed of an In _0.01 Ga _0.99 N layer, a three-period In _0.18 Ga _0.82 N layer and an In _0.05 G
a _0.95 N quantum well active layer etc.), Al _0.2
Ga _0.8 N carrier block layer 806, p-type GaN optical guide layer 807, p-type Al _0.1 Ga _0.9 N cladding layer 808
And a p-type GaN contact layer 809 are sequentially stacked. On the p-type contact layer 809, an insulating film 810 made of SiO ₂ having a stripe-shaped portion serving as a current path is provided, and the opening and the insulating film 810 are provided.
A p-type electrode 812 is provided over the insulating film 8.
The portion above the opening 10 functions as a striped electrode. The p-type contact layer 809 to the n-type contact layer 802 are partially removed so that the surface of the n-type contact layer 802 is exposed.
The n-type electrode 811 is formed on the exposed part of the above.

The n-type contact layer 802 is a lower n-type Ga
The regrown film 802b covers the metal mask 815 with an insulating film, which is composed of the N film 802a and the regrown n-type GaN film 802b and is provided on the lower film 802a below the stripe-shaped electrode. The mask 815 includes a platinum film 813 and an insulating film 814 made of SiN _x provided thereon. The p-type Al _0.1 Ga _0.9 N cladding layer 808 is a lower p-type Al _0.1 Ga _0.9 N film 808 a
And a regrown p-type Al _0.1 Ga _0.9 N clad film 808 b, and the regrown film 808 b covers the metal mask 818 with an insulating film provided on the lower film 808 a below the stripe electrode. . This mask 818 is
It comprises a platinum film 816 and an insulating film 817 made of SiN _x provided thereon.

The nitride semiconductor laser device of this embodiment can be manufactured, for example, as follows. First, as in the second embodiment, the sapphire substrate 8
A low-temperature GaN buffer layer 801 is grown on the GaN buffer layer 801 and then the n-type GaN contact layer 802 has a thickness of 20 μm.
A lower n-type GaN film 802a of m is grown.

Next, as in the second embodiment, the lower GaN
A metal mask 815 with an insulating film having a mask width (M) of 5 μm and a mask thickness of 0.15 μm is formed in a stripe shape in the <1-100> direction on the film 802a. This mask 815 is composed of a platinum film 813 having a thickness of 0.1 μm and a SiN _x film 814 having a thickness of 0.05 μm, and is arranged below a stripe-shaped electrode to be formed in a later step. Next, the substrate was placed in the crystal growth apparatus again,
Similarly to the above, the n-type GaN film 802b having a thickness of 20 μm is regrown to obtain a flat and crack-free n-type GaN film 802b.
An aN contact layer 802 is formed.

Subsequently, as in Embodiment 6, n-type Al
_{A 0.1} Ga _0.9 N clad layer 803, an n-type GaN light guide layer 804, an active layer 805, an Al _0.2 Ga _0.8 N carrier block layer 806, and a p-type GaN light guide layer 807 are grown.

Thereafter, as in Embodiment 6, the p-type Al
_0.1 μm thickness of the _0.1 Ga _0.9 N cladding layer 808
A lower Al _0.1 Ga _0.9 N film 808a is grown. next,
The substrate is once taken out of the crystal growth apparatus, and the lower p-type Al
_With respect to the _0.1 Ga _0.9 N film 808a, a mask width of 3 μm and a mask interval (S) are formed in a stripe shape in the <1-100> direction.
A metal mask 818 with an insulating film having a thickness of 1.5 μm and a mask thickness of 0.2 μm is formed. The mask 818 includes a platinum film 816 having a thickness of 0.1 μm and a Si film having a thickness of 0.1 μm.
A portion 819 composed of an N _x film 817 and not covered with a platinum mask 818 with a SiN _x film is arranged below a stripe-shaped electrode to be formed in a later step. Next, the substrate is placed again in the crystal growth apparatus, and the p-type Al _0.1 Ga _0.9 N film 808b having a thickness of 0.5 μm is grown again. As the growth proceeds, Al _0.1 Ga _0.9 N starts to regrow from the portion 819 not covered with the platinum mask with SiN _x 818, and lateral growth occurs to form the platinum mask 81 with the SiN _x film.
8 were coated. This laterally grown Al _0.1 Ga _0.9 N
The film 808b is completely bonded and has a flat surface cladding layer 8
08 was obtained.

Subsequently, as in Embodiment 6, p-type GaN
A contact layer 809 is grown. After that, the substrate is taken out of the crystal growing apparatus, and a nitride semiconductor laser device of the present embodiment shown in FIG. 8 is manufactured through a semiconductor laser device manufacturing process.

N obtained by such a selective growth step
-Type GaN contact layer 802 and p-type Al _0.1 Ga _0.9
The surface of the N cladding layer 808 was flat and no crack was generated. Dislocations (crystal defects) related to the n-type GaN contact layer 802 were reduced as in the first and second embodiments.

Further, in the nitride semiconductor laser device of this embodiment, regrowth was performed on the GaN contact layer 802 by virtue of the presence of the platinum mask 815 with a SiN _x film having a growth suppressing effect provided in the GaN contact layer 802. In each of the films constituting the later laser structure, the dislocation density was reduced by about two orders of magnitude. As a result, the life characteristic of the semiconductor laser device itself was about 12,000 hours.

The laser oscillation threshold current density of the nitride semiconductor laser device of this embodiment was measured.
5 was reduced to about の of the conventional semiconductor laser device having the ridge stripe structure. In addition, when the modes of the horizontal and vertical modes and the NFP and FFP in the vertical and horizontal modes were observed, laser oscillation was obtained in a single mode with a single peak. Further, the nitride semiconductor laser device of the present embodiment was subjected to a life test of 10,000 hours, and the horizontal and horizontal modes and the vertical and horizontal modes were observed again. Mode and was observed.

The reason why the laser oscillation threshold current density has been reduced in this way is that, similarly to the fifth embodiment, in addition to the laser characteristics of the refractive index waveguide structure described in the fourth embodiment, the current confinement structure is simultaneously provided in the element. This is because it could be built. Further, the reason why a single-peak (single) and stable vertical and transverse mode laser oscillation is obtained is the same as in the first and second embodiments. Also, the formation position of the vertical / horizontal mode, that is,
The formation position of the platinum mask 815 with the SiN _x film is the same as that of the second embodiment in each of a direction perpendicular to and parallel to the substrate. Further, the reason why a single-peak (single) and stable horizontal and transverse mode laser oscillation was obtained is that the sixth embodiment
Is the same as Further, a metal mask with an insulating film (a platinum mask 81 with a SiN _x film) for obtaining a refractive index waveguide structure is used.
The formation position of 5) is the same as that of the sixth embodiment. However, the position of the metal mask with an insulating film in this case refers to the formation position of the metal mask constituting the metal mask with the insulating film, and is the same as the sixth embodiment in this sense. .

In this embodiment, similarly to the sixth embodiment, the active layer 805 and the carrier block layer 806 (the p-type light guide layer 80 when there is no carrier block layer 806).
The distance from the interface of 7) to the metallic mask with an insulating film (a platinum mask with a SiO ₂ film 818) can be set by the crystal growth speed of the crystal growth apparatus. Therefore, as compared with Embodiments 4 and 5, the distance from the interface to the mask can be controlled more accurately, and the light confinement effect in the horizontal and horizontal modes can be controlled more accurately.

Further, the present embodiment has the following effect in addition to the above-described current constriction effect. Embodiment 9 to be described later
GaN using a metallic mask
In the selective growth of the film, generally, the mask is strongly dependent on the stripe direction and the lateral growth is difficult. However, by using the metal mask with the insulating film (the platinum mask with the SiN _x film), the selective growth of the GaN film is also possible. Sufficient lateral growth can be obtained without the direction dependency of the mask pattern. Utilizing this characteristic, in a direction perpendicular to the substrate, within a position range in which a metallic mask 818 with an insulating film can be formed in order to obtain a refractive index waveguide structure (within 2 μm from the upper or lower surface of the active layer). Even if a nitride semiconductor containing no Al exists at (position), selective growth with a high lateral growth rate is possible.

In the present embodiment, platinum (Pt) is used as the metal mask in the metal masks 815 and 818 with an insulating film.
Metals such as Mo, Ni, Al, Pd, and Au, alloys thereof, and a composite film including a plurality of layers including them can be used. If the nitride semiconductor is a metal having a light absorption effect of absorbing the laser light emitted from the active layer, the growth suppression effect is obtained without direct epitaxial growth,
There is no significant dependence on the material. Further, in the metal masks 815 and 818 with an insulating film, a SiO ₂ film may be used as the insulating film other than the SiN _x film, and the insulating film does not largely depend on the material. When the metal mask is covered with the insulating film, it is preferable that the side portion 820 of the metal mask is also covered with the insulating film. Furthermore, a metallic mask 8 with an insulating film
The thicknesses of 15 and 818, the nitrogen carrier gas used for selective growth, the yield, and the like are the same as in the sixth embodiment. In the present embodiment, the metal mask with the insulating film (the platinum mask with SiN _x ) is formed in the n-type GaN contact layer, but the metal mask may be formed. When a metal mask is formed, the same effects as in the first embodiment can be obtained. Further, the metal mask 818 with the insulating film does not need to be completely buried in the cladding layer as in the third embodiment. However, it is preferable to bury the metal mask 818 with the insulating film in the cladding layer in order to improve the yield rate of the laser device production.

In this embodiment, G is used as the low-temperature buffer layer.
Although the example using the aN film has been described, no problem occurs even if Al _x Ga ₁ -xN (0 ≦ x ≦ 1) is used as the low-temperature buffer layer. Further, in the present embodiment, the Al composition of the cladding layer to be regrown is set to 0.1, but 0 <Al ≦ 1.
A similar effect can be obtained with a nitride semiconductor having the following composition.

Furthermore, a synergistic effect can be obtained by combining this embodiment with the above-described fourth or fifth embodiment.

(Embodiment 8) In this embodiment, the relationship between the thickness of the metallic mask and the light absorption will be described.

FIG. 9 is a diagram showing the relationship between the thickness of the tungsten mask and the light absorptivity of the laser beam. According to this figure,
When the thickness of the mask is about 0.01 μm or more, the light absorption rate is 60% or more, and when the thickness is about 0.05 μm or more, almost 100%
Shows the light absorption rate. The relationship shown in FIG. 9 is not limited to tungsten (W), but Pt, Ti, Mo, Ni, A
It was almost the same even when 1, Pd, Au or the like was used. Therefore, in order to obtain a light absorption effect for stabilizing the vertical and horizontal modes by using the metal mask, the thickness of the metal mask (the metal film constituting the metal mask in the case of a metal mask with an insulating film) must be at least. 0.01 μm showing a light absorption of 50% or more
More preferably, more preferably 0.05μ
m or more.

On the other hand, when the metal mask is covered with the nitride semiconductor film, the surface of the semiconductor film must be flat so that the metal mask (the insulating film and the insulating mask in the case of the metal mask with an insulating film) is used. The thickness of the entire mask (including the metal film) is 2μ
m or less.

(Embodiment 9) In this embodiment, the ratio (a / a) between the growth rate in the growth axis direction and the lateral growth rate when a metallic mask and a metallic mask with an insulating film are used.
The relationship between c) and the partial pressure of the nitrogen carrier gas and the stripe direction of the mask will be described.

FIG. 10A shows a state obtained by using a tungsten mask.
In the case of selective growth of GaN film,
Length (a / c) and the partial pressure ratio of nitrogen carrier gas (N_Two/ (H_Two
+ N _Two)). In addition, in FIG.
Therefore, the lateral growth (a / c) is perpendicular to the substrate.
Let the growth rate be c, the growth rate in the direction parallel to the substrate (latate
A) and their ratio a / c.
Was. Further, the partial pressure ratio of the nitrogen carrier gas (N_Two/ (H_Two+ N
_Two)) Is the total carrier gas flow rate (nitrogen carrier gas
Nitrogen carrier (flow rate + flow rate of hydrogen carrier gas)
It was expressed as a gas flow ratio. Further, in FIG.
Orientation is tungsten relative to nitride semiconductor (GaN)
The stripe direction of the mask is shown.

As shown in FIG. 10A, when the stripe direction of the tungsten mask is formed in the <11-20> direction, the lateral growth hardly occurs even if the partial pressure of the nitrogen carrier gas is increased. On the other hand, when the film was formed in the <1-100> direction, lateral growth of about a / c = about 0.4 occurred at a nitrogen carrier gas partial pressure of 0.5. This FIG.
Are not limited to tungsten (W), but Pt,
It was almost the same even when Ti, Mo, Ni, Al, Pd, Au or the like was used.

FIG. 10 (b) shows the case where the AlGaN film is selectively grown using a tungsten mask, and the lateral growth (a / c) and the partial pressure ratio of the nitrogen carrier gas (N ₂ /
(H ₂ + N ₂ )). In FIG. 10B, the lateral growth (a / c), the partial pressure ratio of the nitrogen carrier gas (N ₂ / (H ₂ + N ₂ )) and the orientation are shown in FIG.
Same as (a).

As shown in FIG. 10B, when the stripe direction of the tungsten mask is formed in the <11-20> direction, a / c = about 1.5 at a nitrogen carrier gas partial pressure of 0.5. Lateral growth has occurred. On the other hand, <1-10
When the film was formed in the <0> direction, lateral growth of about a / c = about 15 occurred at a nitrogen carrier gas partial pressure of 0.5.
The relationship shown in FIG. 10B is based on tungsten (W)
Not limited to Pt, Ti, Mo, Ni, Al, Pd, Au
And so on.

According to the results shown in FIGS. 10A and 10B, when the selective growth is performed by utilizing the effect of suppressing the growth of the metallic mask, the stripe direction of the metallic mask is set to <1--1.
100> direction, and it is understood that the partial pressure of the nitrogen carrier gas is preferably higher. However, the selective growth film produced by setting the partial pressure of the nitrogen carrier gas to be larger than 0.9 had an X-ray diffraction half width of 6 minutes or more, and the crystallinity (orientation) was deteriorated. The metallic mask is made of GaN
Lateral growth was faster in the nitride semiconductor film containing at least Al than in the film.

FIG. 11 (a) shows a case where a GaN film is selectively grown using a tungsten mask with an SiO ₂ film and a partial pressure ratio of lateral growth (a / c) to a nitrogen carrier gas (N ₂ / (H ₂ + N _2). )). FIG.
In FIG. 1 (a), in lateral growth (a / c), the growth rate in the direction perpendicular to the substrate is c, and the growth rate in the direction parallel to the substrate (lateral growth rate) is a.
/ C. Further, the partial pressure ratio of the nitrogen carrier gas (N ₂ / (H ₂ + N ₂ )) was expressed as the flow ratio of the nitrogen carrier gas to the flow rate of all the carrier gases (the flow rate of the nitrogen carrier gas + the flow rate of the hydrogen carrier gas). further,
In FIG. 11A, the direction indicates the stripe direction of the tungsten mask with the SiO ₂ film with respect to the nitride semiconductor (GaN).

As shown in FIG. 11A, SiO ₂
Change the stripe direction of the tungsten mask with film to <11-
20> direction, the nitrogen carrier gas partial pressure is 0.1 mm.
In No. 5, lateral growth of about a / c = about 0.5 occurred. On the other hand, when formed in the <1-100> direction, lateral growth of about a / c = about 1.5 occurred at a nitrogen carrier gas partial pressure of 0.5. The relationship shown in FIG. 11A is not limited to tungsten (W), but may be Pt, Ti, Mo, Ni, A
It was almost the same even when 1, Pd, Au or the like was used. Also,
The insulating film was not limited to the SiO ₂ film, and was almost the same even when the SiN _x film was used.

FIG. 11 (b) shows the case where the AlGaN film is selectively grown using a tungsten mask with an SiO ₂ film, and the ratio of the lateral growth (a / c) to the partial pressure of the nitrogen carrier gas (N ₂ / (H ₂ + N _2). )). In addition,
In FIG. 11B, the lateral growth (a / c), the partial pressure ratio of the nitrogen carrier gas (N ₂ / (H ₂ + N ₂ )) and the orientation are the same as in FIG. 11A.

As shown in FIG. 11B, SiO ₂
Change the stripe direction of the tungsten mask with film to <11-
20> direction, the nitrogen carrier gas partial pressure is 0.1 mm.
5, the lateral growth of about a / c = about 8 occurred. on the other hand,
When formed in the <1-100> direction, lateral growth of a / c = about 28 occurred at a nitrogen carrier gas partial pressure of 0.5. The relationship shown in FIG. 11B is not limited to tungsten (W), but may be Pt, Ti, Mo, Ni, Al, P
It was almost the same even when d, Au or the like was used. In addition, the insulating film was not limited to the SiO ₂ film, and was almost the same even when the SiN _x film was used.

From the results of FIGS. 11A and 11B, when the selective growth is performed by utilizing the effect of suppressing the growth of the metal mask with the insulating film, the stripe direction of the metal mask is set to <1--1. 100> direction, and it is understood that the partial pressure of the nitrogen carrier gas is preferably higher. However, the selective growth film produced by setting the partial pressure of the nitrogen carrier gas to be larger than 0.9 had an X-ray diffraction half width of 6 minutes or more, and the crystallinity (orientation) was deteriorated. In the metallic mask, the lateral growth of the nitride semiconductor film containing at least Al was faster than that of the GaN film. Further, the metallic mask with an insulating film has a higher lateral growth than the metallic mask, and the dependence of the mask on the stripe direction has been reduced.

FIGS. 10 (a), 10 (b), 11
11 (a) and FIG. 11 (b), the lateral growth a /
c greatly increases when the nitrogen carrier gas partial pressure is 0.1 or more. For this reason, the partial pressure of the nitrogen carrier gas is set to 0.1.
It is preferably one or more.

Further, from FIGS. 10 and 11, the lower limit value of the lateral growth film necessary for covering the mask including the metal film can be read. This value depends on whether the film to be selectively grown (film to be coated) is a GaN film or AlGa.
It depends on whether it is an N film. Similarly, the direction of the stripe of the mask is also different, which is different between the case where the mask is a metal film only and the case where an insulating film is provided thereon. further,
Varies depending ambient gas ratio _{(N 2 / N 2 + H} 2).

For example, when the stripe direction of the metal mask with an insulating film is set to <1-100> and a GaN film is selectively grown thereon, the atmosphere gas (N ₂ / (N ₂ +
When H ₂ )) = 0.5, it can be read from FIG. 11A that lateral growth a / c = 1.5. That is,
The lateral growth is 1.5 for the lamination film thickness (coating film thickness) 1. The selective growth on the mask starts from the portions on both sides of the mask that are not covered with the mask, and the mask is covered in association at the center of the mask. Therefore, the metal mask is 1.5 × 2 (for both sides) with respect to the laminated film thickness of 1.
= 3. If the mask width is 6 μm
In this case, the mask is covered with the laminated film thickness (lower limit value) of 6/3 = 2 μm. In the above embodiments, N ₂
(10 l / min) + H ₂ (5 l / mi
Selective growth is performed under the condition of n).

(Embodiment 10) In this embodiment, the lower layer n
The metallic mask formed on the p-type AlGaN film is
An example will be described in which a recess is formed without being flatly covered with the type AlGaN film. Other configurations are the same as those of the above-described embodiment.

FIG. 12 shows the structure of the nitride semiconductor laser device of this embodiment. This semiconductor laser device has an n-type Ga
On an N substrate 901, an n-type Al _0.02 Ga _0.98 N contact layer 902, an n-type Al _0.1 Ga _0.9 N cladding layer 903, n
-Type GaN light guide layer 904, active layer 905, Al _0.2 G
An a _0.8 N carrier block layer 906, a p-type GaN light guide layer 907, a p-type Al _0.1 Ga _0.9 N cladding layer 908, and a p-type GaN contact layer 909 are sequentially stacked. On the p-type contact layer 909, an insulating film 910 made of SiO ₂ having a stripe-shaped portion serving as a current path is provided, and a p-type electrode 912 is provided over the opening and the insulating film 910. , Insulating film 91
The portion above the opening of the zero functions as a stripe-shaped electrode. Further, an n-type electrode 911 is formed so as to be in contact with the back surface of the n-type GaN substrate 901.

N-type Al _0.1 Ga _0.9 N clad layer 903
Is composed of a lower n-type Al _0.1 Ga _0.9 N film 903a and a regrown n-type Al _0.1 Ga _0.9 N clad film 903b. Further, a metallic mask (such as a tungsten mask) provided on the lower layer film 903a below the stripe-shaped electrode
Reference numeral 916 has a depression without being flatly covered by the regrown film 403b.

In this embodiment, the metal mask 916 is used.
Is introduced in accordance with the above-described embodiment in order to obtain an optical confinement effect in a horizontal / lateral mode in a semiconductor laser device. However, as a result of a more detailed study by the present inventors, it was found that the following effects were obtained in addition to the light confinement effect in the horizontal and lateral modes.

In FIG. 12, two metallic masks 916 provided below the active layer 905 are provided, and the p-type metal masks 916 and 916 are arranged so as to be located above the interval S between the metallic masks 916 and 916.
The current injection width Wp of the type stripe electrode 412 is provided,
In addition, the metallic mask 916 is formed by the regrown n-type AlGaN film 9.
It has a recess that is not covered flatly by 03b.

In this case, (1) the active layer 905 has a shape similar to a quantum wire structure confined in the direction perpendicular to the stripe direction of the p-type stripe electrode 912 from the quantum well structure by having the concave portion. As a result, the threshold current density can be further reduced. (2) Regrown n-type A
The crystal distortion of the nitride semiconductor layer formed above the lGaN film 903b can be reduced by the depression. This prevents the crystallinity from dropping due to strain,
The laser oscillation life can be further lengthened. Further, (3) the provision of the concave portion can prevent the current injected from the p-type stripe electrode 912 from spreading in the horizontal direction. Thus, the threshold current density can be reduced.

This depression is used to reduce the N ₂ carrier gas partial pressure to 10
%, Preferably by growing the regrown layer 903b in an H ₂ carrier gas atmosphere. Alternatively, it can be formed even when the thickness of the regrown layer 903b is reduced.

In the schematic diagram of FIG. 12, the nitride semiconductor layer laminated on the side wall of the recess is exaggerated. Actually, since the thickness of each nitride semiconductor layer is thin, most of the inside of the depression is not necessarily filled with the nitride semiconductor layer as shown in FIG. The above-described effect according to the present embodiment is more remarkably exhibited as the depth of the recess is deeper. However, if the depth is too deep, it becomes difficult to form a stripe-shaped electrode. The position of the depression is formed above the center of the mask width with high reproducibility.

(Embodiment 11) In this embodiment, the lower layer p
The metallic mask formed on the p-type AlGaN film is
An example will be described in which a recess is formed without being flatly covered with the type AlGaN film. Other configurations are the same as those of the above-described embodiment.

FIG. 13 shows the structure of the nitride semiconductor laser device of this embodiment. This semiconductor laser device has an n-type Ga
On an N substrate 1001, an n-type Al _0.02 Ga _0.98 N contact layer 1002 and an n-type Al _0.1 Ga _0.9 N cladding layer 100
3, n-type GaN light guide layer 1004, active layer 1005,
Al _0.2 Ga _0.8 N carrier block layer 1006, p-type G
An aN light guide layer 1007, a p-type Al _0.1 Ga _0.9 N cladding layer 1008, and a p-type GaN contact layer 1009 are sequentially laminated. On the p-type contact layer 1009, SiO having a stripe-shaped portion serving as a current path is opened.
_An insulating film 1010 made of ₂ is provided, and a p-type electrode 1012 is provided over the opening and over the insulating film 1010. The portion of the insulating film 1010 over the opening functions as a striped electrode. Further, an n-type electrode 1011 is formed so as to be in contact with the back surface of the n-type GaN substrate 1001.

A p-type Al _0.1 Ga _0.9 N cladding layer 1008
Is formed with a lower p-type Al _0.1 Ga _0.9 N film 1008a and a regrown p-type Al _0.1 Ga _0.9 N film 1008a.
It is composed of a type Al _0.1 Ga _0.9 N clad film 1008b. The lower film 1008 below the stripe-shaped electrode
The metallic mask (tungsten mask or the like) 1016 provided on the upper portion a is not flatly covered with the regrown film 1008b but has a depression.

In the present embodiment, the metallic mask 101
Numeral 6 is introduced according to the above-described embodiment in order to obtain a horizontal-lateral mode light confinement effect in the semiconductor laser device. However, as a result of a more detailed study by the present inventors, it was found that the following effects were obtained in addition to the light confinement effect in the horizontal and lateral modes.

In FIG. 13, two metal masks 1016 are provided above the active layer 1005, and the p-type stripe electrode 1012 is positioned above the space S between the metal masks 1016 and 1016. The current injection width Wp is provided, and the metallic mask 1016 is made of a regrown n-type A
It has a dent that is not flatly covered by the lGaN film 1008b.

In this case, by having the recessed portion,
The crystal distortion of the nitride semiconductor layer formed above the regrown p-type AlGaN film 1008b can be reduced by the depression. As a result, a decrease in crystallinity due to distortion can be prevented, and the laser oscillation life can be further lengthened.

This depression is used to reduce the N ₂ carrier gas partial pressure to 10
%, Preferably by growing the regrown layer 1008b in an H ₂ carrier gas atmosphere. Alternatively, it can be formed even when the thickness of the regrown layer 1008b is reduced.

In the schematic diagram of FIG. 13, the nitride semiconductor layer laminated on the side wall of the recess is exaggerated. Actually, since the thickness of each nitride semiconductor layer is thin, most of the inside of the recess is not necessarily filled with the nitride semiconductor layer as shown in FIG. The above-described effect according to the present embodiment is more remarkably exhibited as the depth of the recess is deeper. However, if the depth is too deep, it becomes difficult to form a stripe-shaped electrode. The position of the depression is formed above the center of the mask width with high reproducibility.

(Embodiment 12) In this embodiment, an n-type G
The metallic mask formed on the aN substrate is a regrown n-type Al
An example will be described in which a GaN film is not flatly covered but has a depression. Other configurations are the same as those of the above-described embodiment.

FIG. 14 shows the structure of the nitride semiconductor laser device of this embodiment. This nitride semiconductor laser device has n
An n-type Al _0.02 Ga _0.98 N contact layer 1102, an n-type Al _0.1 Ga _0.9 N cladding layer 1103, an n-type GaN optical guide layer 1104, and an active layer 11 are formed on an n-type GaN substrate 1101.
05, an Al _0.2 Ga _0.8 N carrier block layer 1106,
p-type GaN optical guide layer 1107, p-type Al _0.1 Ga _0.9 N
Cladding layer 1108 and p-type GaN contact layer 11
09 are sequentially stacked. The p-type cladding layer 1108 is dug down to the vicinity of the p-type light guide layer 1107 to form a ridge stripe portion composed of the p-type contact layer 1109 and the p-type cladding layer 1108. An insulating film 1110 made of SiO ₂ is provided thereon, and the upper part of the ridge stripe is opened. The insulating film 11
A p-type electrode 1112 is provided over the ridge stripe portion exposed from the opening of the insulating film 1110 on the ridge stripe 10, and the portion on the ridge stripe functions as a stripe-shaped electrode. An n-type electrode 1111 is formed so as to be in contact with the back surface of n-type GaN substrate 1101.

Further, a metallic mask (such as a tungsten mask) 1116 provided on a portion of the substrate below the ridge stripe portion is not covered with the contact layer 1102 but has a depression.

In this embodiment, the metallic mask is formed at a position within half of the total thickness of the contact layer and the substrate from the interface between the cladding layer and the contact layer toward the substrate.

In this embodiment, the metallic mask 111
Numeral 6 is introduced according to the above-described embodiment in order to obtain a horizontal-lateral mode light confinement effect in the semiconductor laser device. However, as a result of a more detailed study by the present inventors, it was found that the following effects were obtained in addition to the light confinement effect in the horizontal and lateral modes.

In FIG. 14, a metal mask 1116 provided below the active layer 1105 is provided.
A current injection width Wp of a ridge stripe structure is provided above at least one of the region M1 and the region M2 in which the contact layer 16 is flatly covered with the contact layer 1102.

[0209] In this case, by having the concave portion,
The crystal distortion of the nitride semiconductor layer formed above the n-type AlGaN contact layer 1102 can be reduced by the depression. As a result, a decrease in crystallinity due to distortion can be prevented, and the laser oscillation life can be further lengthened.

[0210] This depression is used to reduce the partial pressure of the N ₂ carrier gas to 10%.
%, Preferably by growing the contact layer 1102 in an H ₂ carrier gas atmosphere. Alternatively, it can be formed even when the thickness of the contact layer 1102 is reduced.

In the schematic diagram of FIG. 14, the nitride semiconductor layer laminated on the side wall of the recess is exaggerated. Actually, since the thickness of each nitride semiconductor layer is thin, most of the inside of the recess is not necessarily filled with the nitride semiconductor layer as shown in FIG. The above-described effect according to the present embodiment is more remarkably exhibited as the depth of the recess is deeper. However, if the depth is too deep, it becomes difficult to form a stripe-shaped electrode. The position of the depression is formed above the center of the mask width with high reproducibility. In the present embodiment, since the growth starts from both sides of the metallic mask, the depression is formed only on one side of the ridge stripe.

In this embodiment, the metallic mask 111
6, the n-type Al _0.02 Ga _0.08 N contact layer 1102 may have another Al composition ratio.
aN. The effect of the component of the layer formed on the metal mask 1116 being AlGaN and the effect of the component of the layer formed on the metal mask 1116 being GaN are described in the above-described embodiment. Is the same as

In the tenth to twelfth embodiments, the metal mask has been described. However, a metal mask with an insulating film may be used. The effect of using the metal mask with an insulating film is the same as in the above-described embodiment,
The formation method is the same. However, when a metal mask with an insulating film is used, lateral growth is likely to occur.
The metal mask is easier to form the depression. Also, Ga
An n-type electrode was formed from the back side of the N substrate.
As described above, an n-type electrode may be formed from the same side as the p-type electrode. Further, in the above-described Embodiments 10 to 12, the shape of the depression is V-shaped, but may have another shape, for example, a rectangular shape. For example, when the stripe direction of the mask is formed along the <1-100> direction of the nitride semiconductor crystal, a rectangular recess is easily formed.

(Embodiment 13) In this embodiment, the effect of combining a metal mask or a metal mask with an insulating film with a GaN substrate (an example of a nitride semiconductor substrate) will be described.

The inventors of the present application have conducted detailed studies. As a result, when the above-mentioned metallic mask is formed on a nitride semiconductor layer (hereinafter, referred to as an underlayer), the metal constituting the metallic mask becomes lower. Internal diffusion occurred in the stratum. Such internal diffusion of the metal lowers the crystallinity and lowers the yield. In order to prevent such internal diffusion, the deposition temperature when forming the metallic mask and the growth temperature of the nitride semiconductor layer covering the metallic mask were controlled to some extent.

However, by using a nitride semiconductor substrate (for example, a GaN substrate) as the substrate, the internal diffusion of the metal can be more effectively suppressed, and the yield can be improved. The reason is as follows. According to the experimental results of the present inventors, it has been found that the internal diffusion of the metal is diffused into the underlying layer through threading dislocations. Since the threading dislocation density in a nitride semiconductor film grown on a GaN substrate is lower than that on a heterogeneous substrate (for example, a sapphire substrate) other than a nitride semiconductor substrate, using a GaN substrate ,
The internal diffusion of the metal can be more effectively suppressed.

In this embodiment, the metal mask has been described, but the same effect can be obtained by using a metal mask with an insulating film.

In the first to thirteenth embodiments, examples in which crystal growth is performed by the MOCVD method have been described. However, the present invention is not limited to this. For example, the MBE method, the hydride vapor phase growth method, the MOMBE method, the CVD method, etc. Other growth methods may be used. The substrate is not limited to sapphire.
H-SiC, 4H-SiC, 3C-SiC, GaN, G
Other substrates such as aAs, Si, Ge, and MgAl ₂ O ₄ can be used. Further, another nitride semiconductor substrate such as an AlGaN substrate or an InGaN substrate may be used. Further, the mixed crystal ratio of each layer can be appropriately changed. _{Moreover, Al x Ga y In 1-} xy N (0 ≦ x ≦ 1,0 ≦ y ≦
1) A similar effect can be obtained by using a material in which a part (about 10% or less) of a nitrogen element is replaced with at least one of P, As, and Sb among the nitride semiconductor constituent elements. .

[0219]

As described in detail above, according to the present invention,
The following effects can be obtained by applying a mask including a metal film having at least a light absorbing function to a nitride semiconductor laser device.

First, due to the light absorption effect of the metal film,
It is possible to stabilize a single-peak vertical / transverse mode.

Second, due to the light absorption effect of the metal film,
By imparting an equivalent refractive index difference to the light guide layer, the light confinement in the horizontal and transverse modes can be enhanced, the threshold current density can be reduced, and the unimodal horizontal and transverse modes can be stabilized.

Third, by covering the metal film with an insulating film, the lateral growth rate can be improved and a current confinement structure can be realized. As a result, the first and second effects can be more remarkably obtained.

Fourth, since the metal film has a growth suppressing effect in addition to the light absorbing effect, the dislocation density in the nitride semiconductor film constituting the laser structure can be reduced together with the above effect. For this reason, the oscillation lifetime characteristics of the laser can be improved.

The nitride semiconductor laser device of the present invention having such excellent characteristics is very useful as a display device, a display, a light source for an optical disk, or the like.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a schematic configuration of a nitride semiconductor laser device according to a first embodiment.

FIG. 2 is a schematic diagram illustrating a schematic configuration of a crystal growth apparatus used in the embodiment.

FIG. 3 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device according to a second embodiment.

FIG. 4 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device of a third embodiment.

FIG. 5 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device of a fourth embodiment.

FIG. 6 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device of a fifth embodiment.

FIG. 7 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device according to a sixth embodiment.

FIG. 8 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device of a seventh embodiment.

FIG. 9 is a graph showing a relationship between a film thickness of a metallic mask (tungsten mask) and a light absorption rate.

FIG. 10A is a diagram showing a relationship between a lateral growth ratio and a partial pressure of a nitrogen carrier gas in a GaN film selectively grown using a metallic mask (tungsten mask), and FIG. Metallic mask (tungsten mask)
FIG. 4 is a diagram showing a relationship between a lateral growth ratio and a partial pressure of a nitrogen carrier gas for an AlGaN film that has been selectively grown by using FIG.

FIG. 11A shows a metallic mask with an insulating film (SiO 2).
FIG. 3B is a diagram showing the relationship between the lateral growth ratio and the partial pressure of a nitrogen carrier gas for a GaN film selectively grown using a tungsten mask with _two films, and FIG. Tungsten mask with _two films)
FIG. 4 is a diagram showing a relationship between a lateral growth ratio and a partial pressure of a nitrogen carrier gas for an AlGaN film that has been selectively grown by using FIG.

FIG. 12 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device according to a tenth embodiment.

FIG. 13 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device according to an eleventh embodiment.

FIG. 14 is a schematic sectional view showing a schematic configuration of a nitride semiconductor laser device of Embodiment 12.

FIG. 15 is a diagram showing a configuration of a conventional nitride semiconductor laser device having a ridge stripe structure.

16A is a vertical transverse mode NFP in a nitride semiconductor laser device of the present invention, and FIG. 16B is a vertical transverse mode NFP in a conventional nitride semiconductor laser device.

17A is a vertical transverse mode FFP in a nitride semiconductor laser device of the present invention, and FIG. 17B is a vertical transverse mode FFP in a conventional nitride semiconductor laser device.

[Explanation of symbols]

10, 100, 300, 500, 600, 700, 80
0 Sapphire substrate 11, 101, 301, 501, 601, 701, 80
1 Low temperature GaN buffer layer 12, 102, 302, 502, 602, 702, 80
2 n-type GaN contact layer 13, 103, 303, 403, 503, 603, 70
3, 803, 903, 1003, 1103 n-type AlG
aN cladding layer 14, 104, 304, 404, 504, 604, 70
4,804,904,1004,1104 n-type GaN
Light guide layer 15, 105, 305, 405, 505, 605, 70
5, 805, 905, 1005, 1105 Active layer 16, 106, 306, 406, 506, 606, 70
6,806,906,1006,1106 AlGaN
Carrier block layer 17, 107, 307, 407, 507, 607, 70
7,807,907,1007,1107 p-type GaN
Light guide layer 18, 108, 308, 408, 508, 608, 70
8,808,908,1008,1108 p-type AlG
aN cladding layer 19, 109, 309, 409, 509, 609, 70
9,809,909,1009,1109 p-type GaN
Contact layer 20, 110, 310, 410, 510, 610, 71
0,810,910,1010,1110 SiO ₂ insulating film 21,111,311,411,511,611,71
1, 811, 911, 1011, 1111 n-type electrodes 22, 112, 312, 412, 512, 612, 71
2, 812, 912, 1012, 1112 p-type electrode 23 near the active layer where the ridge stripe is formed 24 near the active layer where the ridge stripe is dug 102a, 302a, 502a, 602a, 702a,
802a Lower n-type GaN film 102b, 302b, 502b, 602b, 702b,
802b Regrown n-type GaN film 113, 416, 516 Tungsten mask 201 Substrate 202 Susceptor 203 Reaction tube 204 Raw material inlet 205 Exhaust gas outlet 206 Ammonia 207a TMG 207b TMA 207c TMI 207d Cp ₂ Mg 208 Mass flow controller 209 SiH ₄ 313, 513, 613,616 tungsten film 314,514,614,617 SiO ₂ film 315,515,615,618 SiO ₂ film with a tungsten mask 401,901,1001,1101 n-type GaN substrate 402,902,1002,1102 n-type AlGaN
Contact layer 403a, 503a, 603a, 903a Lower n-type A
lGaN films 403b, 503b, 603b, 903b Regrown n-type AlGaN films 417, 517, 619, 717, 819 Parts not covered with mask 620, 820 Side parts of mask 708a, 808a, 1008a Lower p-type AlGaN
Film 708b, 808b, 1008b Regrown p-type AlGa
N film 713, 813, 816 Platinum film 714, 814, 817 SiN _x film 715, 815, 818 Platinum mask with SiN _x film 716 Platinum mask 916, 1016, 1116 Metal mask

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Ueda 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Jun Ogawa 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside the corporation

Claims (13)

[Claims] 1. A semiconductor laminated structure made of a nitride semiconductor on a substrate, and a mask including at least a metal film having a light absorbing function is provided in a region where guided light reaches in the semiconductor laminated structure. Nitride semiconductor laser device. 2. The semiconductor laminated structure according to claim 1, wherein the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown, and the semiconductor laminated structure has a pair of clad layers and an active layer sandwiched between the clad layers. A stripe-shaped electrode on the surface opposite to the substrate, in contact with the lower surface of the clad layer closer to the substrate, having a higher refractive index than the clad layer, and having a different refractive index from the substrate. Having a contact layer, the metal film is disposed at a position below the stripe-shaped electrode and within a half of the contact layer thickness from the interface between the cladding layer and the contact layer toward the substrate, A contact layer having a higher refractive index than the cladding layer and having substantially the same refractive index as the substrate, in contact with the lower surface of the cladding layer closer to the substrate; Whether the metal film is located below the pole and at a position within half of the total thickness of the contact layer thickness and the substrate thickness from the interface between the cladding layer and the contact layer toward the substrate, The clad layer closer to the substrate has a lower refractive index than the substrate, and there is no contact layer between the substrate and the clad layer. The metal film is disposed at a position within half the thickness of the substrate from the interface with the substrate and the lower surface of the substrate, or the metal film is located below the stripe-shaped electrode and close to the substrate. 2. The nitride semiconductor laser device according to claim 1, wherein the metal film is disposed on or within the cladding layer of (a), at a position of 0.5 μm or more from the lower surface of the active layer toward the substrate. 3. 3. The semiconductor device according to claim 1, wherein the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown. The semiconductor laminated structure has a pair of cladding layers and an active layer sandwiched between both cladding layers. A ridge stripe portion provided above and having a contact layer having a refractive index higher than that of the cladding layer and having a refractive index different from that of the substrate in contact with a lower surface of the cladding layer closer to the substrate; The metal film is disposed at a position below the stripe portion and within a half of the thickness of the contact layer from the interface between the cladding layer and the contact layer toward the substrate, or the cladding layer closer to the substrate. A contact layer having a higher refractive index than the cladding layer and having substantially the same refractive index as the substrate, and in contact with the lower surface of the ridge stripe portion, The metal film is arranged at a position within half of the total thickness of the contact layer thickness and the substrate thickness from the interface between the cladding layer and the contact layer toward the substrate, or the cladding layer closer to the substrate Has a lower refractive index than the substrate, and there is no contact layer between the substrate and the cladding layer, and is located below the ridge stripe portion and from the interface between the cladding layer and the substrate. The metal film is arranged at a position within half of the thickness of the substrate toward the lower surface of the substrate, or under the ridge stripe portion, and
0.5 μm from the lower surface of the active layer toward the substrate, on or within the cladding layer closer to the substrate.
2. The nitride semiconductor laser device according to claim 1, wherein said metal film is arranged at the above positions. 4. The semiconductor device according to claim 1, wherein the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown. The semiconductor laminated structure has an active layer, and a stripe-shaped surface of the semiconductor laminated structure opposite to the substrate is provided. An electrode, wherein the metal film is disposed at a position within 2 μm from a lower surface or an upper surface of the active layer, and a mask including the metal film is provided below the stripe-shaped electrode in a portion not covered with the mask. The nitride semiconductor laser device according to claim 1, wherein the semiconductor laser device is provided. 5. The semiconductor device according to claim 1, wherein the metal film is made of a metal on which a nitride semiconductor is not directly epitaxially grown. The semiconductor laminated structure has a pair of clad layers and an active layer sandwiched between both clad layers. A ridge stripe portion is provided above, the metal film is arranged at a position within 2 μm from the lower surface or the upper surface of the active layer, and a mask including the metal film is covered with the mask below the ridge stripe portion. The nitride semiconductor laser device according to claim 1, wherein the nitride semiconductor laser device is arranged to have a portion that is not provided. 6. The method according to claim 1, wherein the distance between the masks is 1 μm or more and 15 μm or more.
The nitride semiconductor laser device according to claim 4, wherein m is equal to or less than m. 7. The nitride semiconductor laser device according to claim 1, wherein the thickness of the metal film is 0.01 μm or more, and the thickness of the entire mask including the metal film is 2 μm or less. . 8. The method according to claim 1, wherein the metal film is made of W, Ti, Mo, Ni,
A metal film containing at least one of Al, Pt, Pd, Au and their alloys, or a composite film composed of a plurality of layers containing at least one of these metals and alloys. A nitride semiconductor laser device according to claim 7. 9. The nitride semiconductor laser device according to claim 1, wherein said mask is covered with an insulating film immediately above said metal film. 10. The insulating film is made of SiO ₂ or SiN _x.
The nitride semiconductor laser device according to any one of claims 1 to 9, comprising: 11. The nitride semiconductor according to claim 1, wherein said metal film is provided in a stripe shape in a <1-100> direction with respect to an underlying nitride semiconductor layer. Laser element. 12. The mask including the metal film is not covered with the nitride semiconductor layer on the mask, but has a recess.
The nitride semiconductor laser device according to any one of the above. 13. The method for manufacturing a nitride semiconductor laser device according to claim 1, wherein when the mask is covered with a nitride semiconductor layer, all the carrier gases are removed. A method for manufacturing a nitride semiconductor laser device using a nitrogen carrier gas of 10% or more.