JP2003273470A - Iii-group nitride semiconductor laser element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride semiconductor laser element including a III-group nitride semiconductor as a substrate which exhibits an excellent operation characteristic and assures a longer laser oscillation life. <P>SOLUTION: A laser beam guiding region of the III-group nitride semiconductor laminated layer structure on a GaN substrate is provided at the position deviated from the upper side of a relocation concentrated region vertically penetrating the substrate. Moreover, electrodes provided on the upper surface of the laminated layer structure and the lower surface of the substrate are provided at positions deviated from the upper and lower sides of the relocation concentrated region. It is also possible that dielectric material layers are provided at upper and lower portions of the relocation concentrated region between the upper surface of laminated layer structure and the lower surface of substrate, and the electrodes are not in contact with the positions. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device made of a group III nitride semiconductor.

[0002]

2. Description of the Related Art Generally, In _x Ga _y Al _z N (however,
0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, x + y + z =
The group III nitride semiconductor represented by 1) has a large energy band gap and high thermal stability, and the band gap width can be controlled by adjusting its composition. For this reason, application development is proceeding on various semiconductor devices such as light emitting devices and high temperature devices.

As a light emitting element, a light emitting diode (LED) having a luminous intensity of several cd class in the light wavelength range from blue to green has already been put into practical use, and a laser diode (LD) is also used.
Even so, it is in the stage of being developed for practical use. From the beginning of development, it has been attempted to use an insulating substrate, such as sapphire, which is relatively easily available, for the laser diode.

[0004]

However, in the device using the sapphire substrate, there is a large lattice mismatch between the substrate and the epitaxial layer (about 14 sapphire C-plane and GaN crystal).
%) And high-density dislocation defects (10 ⁸ to 10 ¹⁰ cm ⁻² ) introduced into the epitaxial layer have adversely affected the characteristics including the device life. Also, when sapphire is used as the substrate of the semiconductor laser device, the cleavage direction of the substrate and the epitaxial layer are different,
If the cleavage method, which is a general method, is used to form the end face of the resonator, there is a problem that it is difficult to obtain a good end face.

In order to avoid these problems, there have been attempts to use, for example, SiC or the like as a substrate other than sapphire. However, the size of the substrate, the availability, the lattice mismatch, etc. have not been essentially improved.

From the viewpoints of elimination of lattice mismatch between the substrate and the epitaxial layer, reduction of defects, good crystallinity, etc., the inventors of the present invention use a device in which GaN, which is a group III nitride semiconductor, is used as the substrate, like the epitaxial layer. Is under development.

As a result, it has become possible to greatly improve the characteristics of the nitride semiconductor laser device. However, even if a GaN substrate is used, a good nitride semiconductor laser device is not always obtained and the operating current is It has also been found that the value may gradually increase or the characteristics may suddenly decrease. When the inventors of the present invention conducted a detailed investigation on the cause,
There are several methods for manufacturing a GaN substrate, and the substrates manufactured by the respective methods are structurally and qualityally different, so that the influence appears in the laminated structure on the substrate and the characteristics of the nitride semiconductor laser device. It has become clear that it has a big influence on.

The present invention is a nitride semiconductor laser device including a group III nitride semiconductor as a substrate, and by optimizing the structure of the device for each substrate, the operating characteristics are excellent and the laser oscillation life is long. The purpose is to provide a long one.

[0009]

In order to achieve the above object, the present invention provides a substrate made of a group III nitride semiconductor, a laminated structure made of a group III nitride semiconductor provided on the upper surface of the substrate, and a laminated structure. A semiconductor laser device including an electrode provided on the upper surface of the structure has a dislocation concentration region where the substrate reaches the upper surface from the lower surface and a low dislocation region which is a portion excluding the dislocation concentration region, and the laminated structure has a low dislocation density of the substrate. Has a striped laser light waveguide region located only above the region,
The electrode is located only above the low dislocation region of the substrate.

This semiconductor laser device includes a substrate made of a group III nitride semiconductor, and a dislocation concentration region penetrating in the vertical direction is present in the substrate, but a laser optical element included in a laminated structure made of a group III nitride semiconductor. The wave region is not located above the dislocation-concentrated region but above the low-dislocation region, which is a region other than the dislocation-concentrated region. Therefore, even if the dislocation-concentrated region of the substrate influences the laminated structure and a defect occurs in a portion above the dislocation-concentrated region in the laminated structure, the laser light waveguide region is deviated from the defect, which is favorable. It has various characteristics.

Further, since the electrode provided on the upper surface of the stacked structure is also located above the low dislocation concentration region, not above the dislocation concentrated region, defects in the region above the dislocation concentrated region are located on the upper surface of the stacked structure. Even if it reaches and is exposed, it will come off from that part. Therefore, it is possible to prevent the current from flowing through the dislocation concentration region of the substrate and the defect portion in the laminated structure that may be generated thereover, and suppress the deterioration of the laser light waveguide region due to the increase of the operating current. .

The present invention also provides a semiconductor laser device including a substrate made of a group III nitride semiconductor, a laminated structure made of a group III nitride semiconductor provided on the upper surface of the substrate, and an electrode provided on the lower surface of the substrate. A stripe laser light guiding region in which the substrate has a dislocation-concentrated region reaching from the lower surface to the upper surface and a low-dislocation region which is a region excluding the dislocation-concentrated region, and the laminated structure is located only above the low-dislocation region of the substrate. And the electrode is located only below the low dislocation region of the substrate.

Although the substrate of this semiconductor laser device also has a dislocation concentration region penetrating in the vertical direction, the laser light waveguide region is located above the low dislocation region and not above the dislocation concentration region, so that the stacked layers are stacked. Even if a defect occurs in a region above the dislocation-concentrated region in the structure, it will be out of the defect, and thus it has good characteristics. Although the lower end of the dislocation-concentrated region is exposed on the lower surface of the substrate, the electrode provided on the lower surface of the substrate is located below the low-dislocation-distributed region, not below the dislocation-concentrated region, so the dislocation-concentrated region is exposed. Remove from the site. Therefore, current can be prevented from flowing through the dislocation concentrated region, and deterioration of the laser light waveguide region due to increase in operating current can be suppressed.

The present invention also provides a semiconductor laser device comprising a substrate made of a group III nitride semiconductor and a laminated structure made of a group III nitride semiconductor provided on the upper surface of the substrate.
The substrate has a dislocation-concentrated region extending from the lower surface to the upper surface and a low-dislocation region that is a portion excluding the dislocation-concentrated region, and the laminated structure has a stripe-shaped laser light guiding region located only above the low-dislocation region of the substrate. A current blocking layer is provided on a portion of the lower surface of the substrate located below the dislocation concentrated region and on a portion of the upper surface of the laminated structure located above the dislocation concentrated region of the substrate.

The substrate of this semiconductor laser device also has a dislocation concentration region penetrating in the vertical direction, but since the laser light guiding region is located above the low dislocation region but not above the dislocation concentration region, the stacked layers are stacked. Even if a defect occurs in a region above the dislocation-concentrated region in the structure, it will be out of the defect, and thus it has good characteristics. Further, the lower end of the dislocation concentration region is exposed on the lower surface of the substrate, but since a current blocking layer is provided at this portion of the lower surface of the substrate, it is assumed that a part of the electrode provided on the lower surface of the substrate is located at this portion. However, there is no current flowing between the electrode and the dislocation concentrated region.

Further, even if a defect generated above the dislocation concentrated region reaches the upper surface of the laminated structure and is exposed, a current blocking layer is provided at this portion of the upper surface of the laminated structure.
Even when part of the electrode provided on the upper surface of the laminated structure is located at this portion, there is no current flowing between the electrode and the defective portion in the laminated structure. Therefore, it is possible to prevent the current from flowing through the dislocation-concentrated region of the substrate or the defective portion in the laminated structure that may occur, and suppress the deterioration of the laser light waveguide region due to the increase in the operating current.

The present invention also provides a semiconductor laser device having a substrate made of a group III nitride semiconductor and a laminated structure made of a group III nitride semiconductor provided on the upper surface of the substrate.
The substrate has a dislocation-concentrated region extending from the lower surface to the upper surface and a low-dislocation region that is a portion excluding the dislocation-concentrated region, and the laminated structure has a stripe-shaped laser light guiding region located only above the low-dislocation region of the substrate. The current blocking layer is provided in a portion of the laminated structure located above the dislocation concentration region of the substrate.

The substrate of this semiconductor laser device also has a dislocation concentration region penetrating in the vertical direction, but since the laser light waveguide region is located above the low dislocation region rather than above the dislocation concentration region, the stacked layers are stacked. Even if a defect occurs in a region above the dislocation-concentrated region in the structure, it is out of the defect and has good characteristics. Further, since the current blocking layer is provided in the portion above the dislocation concentration region in the laminated structure, even if a defect occurs in this portion, the current does not flow in this portion. Therefore, it is possible to prevent the current from flowing through the dislocation-concentrated region of the substrate and the defective portion in the laminated structure that may occur, and suppress the deterioration of the laser light waveguide region due to the increase of the operating current.

The dislocation-concentrated region of the substrate may have a stripe shape which is substantially parallel to the laser light waveguide region of the laminated structure when viewed from above. The dislocation-concentrated region having such a shape facilitates formation of the laser light waveguide region. Further, the formation of the electrodes and the current blocking layer becomes easy.

The current blocking layer is made of SiO ₂ , SiN, SiO,
ZnO, PbO, TiO ₂ , ZrO ₂ , CeO ₂ , Hf
_{O 2, Al 2 O 3,} Bi 2 O 3, Cr 2 O 3, In 2 O 3, Nd 2
O ₃ , Sb ₂ O ₃ , Ta ₂ O ₅ , Y ₂ O ₃ , AlF ₃ , Ba
F ₂ , CeF ₂ , CaF ₂ , MgF ₂ , NdF ₃ , PbF ₂ ,
At least one of SrF ₂ , ZnS, and ZnSe
It can be a dielectric including a type.

The thickness of the current blocking layer is 1 nm or more and 1 μm.
The following is preferable. By setting the thickness within this range, it is possible to reliably cut off the electric current and avoid occurrence of mechanical defects such as cracks and peeling.

When the dislocation concentrated region is formed in a stripe shape substantially parallel to the laser light guiding region, the width of the current blocking layer is preferably 5 μm or more and 300 μm or less. By setting the width within this range, while surely interrupting the current of the defect portion that may occur in the dislocation concentration region or the laminated structure,
It can be easily avoided that the current blocking layer interferes with the current to be guided to the laser light guiding region.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiments of the present invention, a GaN substrate used in the semiconductor laser device of each embodiment will be described with reference to FIGS. Note that when the index indicating the plane or orientation of the crystal is negative, it is the rule of crystallography to write a horizontal line above the absolute value, but in this specification such a notation is not possible, A negative sign "-" is added before the absolute value to represent a negative index.

FIG. 14 is an enlarged view of a part of the GaN substrate under fabrication.
FIG. 15 is a schematic vertical cross-sectional view, and FIG.
It is a perspective view which shows typically. First, the proper wafer surface
Support substrate 21 in which a striped mask is periodically applied
To prepare. Here, the wafer is the (111) surface
2 inch GaAs wafer, SiO as mask ₂
It was used. Next, HVPE method (Hydride Vapor Phase)
Epitaxy) to facet the n-type GaN layer 22
The {11-22} plane 23 is mainly exposed on the growing surface.
So that it grows in the [0001] direction. as a result,
As shown in FIG. 14, the cross section of the surface has a serrated uneven shape.
Become. The {0001} plane 25 is exposed near the apex of the protrusion
The parts that appeared were striped.

The concavo-convex shape extends like a ridge in the depth direction of FIG. 14, and the pitch of the concavo-convex shape is defined by the arrangement shape of the SiO ₂ mask initially formed on the support base 21. That is, there is a SiO ₂ mask below the concave and convex portions, and when a perpendicular is drawn from the convex portion to the supporting base 21, the SiO ₂ mask is formed.
_{2 A} line that crosses the center of the opening of the mask. Here, the shape of the SiO ₂ mask is a periodic structure with a pitch of 400 μm, and therefore the pitch of the uneven shape is also a pitch of about 400 μm. The [1-100] direction of the mask opening and the n-type GaN layer 22 are substantially parallel to each other.

In this example, since the SiO ₂ mask has a stripe shape, the uneven shape of the surface of the n-type GaN layer 22 also has a ridge shape, but the mask shape is not limited to a band shape, but a dot shape. You can also do it. In that case, the surface shape of the n-type GaN layer 22 is such that a mortar-shaped recess whose bottom is located above the mask is lined up, and facet {11-22} faces are exposed on the sloped portion of the mortar. Will be done. Regarding the method (growth condition) for maintaining the crystal growth with the facet {11-22} planes exposed, Japanese Patent Application No. 11-
No. 273882 is disclosed in detail. The conductivity type of the growing crystal was changed to n-type by doping oxygen during growth.

By continuing the crystal growth of the n-type GaN layer while maintaining the growth mode having the above-mentioned concavo-convex shape on the surface, as shown in FIG.
An m ingot was prepared. In FIG. 15, fine lines on the upper surface of the ingot schematically represent the ridges on the surface.

This ingot is cut by a slicer to make a thin piece, and the thin piece is polished and processed into a wafer having a flat surface having a diameter of 2 inches (about 5 cm) and a thickness of 350 μm, and an n-type GaN substrate. Set to 10. The surface of the wafer is mirror-polished for subsequent epitaxial growth. Although this surface is almost the (0001) plane, when the morphology of the nitride semiconductor layer epitaxially grown on the surface is compared, it has an off angle in the range of 0.2 to 1 ° from the (0001) plane in any direction. It is desirable that the morphology is best in the range of 0.4 to 0.8 °. 16 and 17 show a vertical sectional view and a top view, respectively, of a part of the obtained n-type GaN substrate 10.

Next, the n-type GaN substrate 10 was evaluated. First, when the surface of the substrate was observed in detail with an optical microscope, it was found that the polished surface was not always flat and that n-type G
The bottom 24 of the recess during crystal growth of the aN layer 22 (FIG. 14)
The stripe-shaped region corresponding to the portion where was generated was slightly depressed. This corresponds to the part X2 in FIG.

Further, the surface of the n-type GaN substrate 10 was treated with a mixed acid of sulfuric acid and phosphoric acid at 250 ° C., and the exposed etch pits were observed. As a result, a large number of etch pits were formed in the stripe-shaped regions corresponding to the above-mentioned depressions. Was observed, and it was found that this is a region where dislocations (defects) are extremely concentrated. It is considered that the portion where dislocations are concentrated has a lower mechanical strength than the other portions and is therefore easily damaged during the polishing process, resulting in the formation of depressions on the substrate surface.

The width of the stripe-shaped region in which dislocations were concentrated was about 5 to 40 μm, and the etch pit density at this portion was as large as 10 ⁵ to 10 ⁹ pieces / cm ² . On the other hand, the etch pit density of the portion other than the striped region was suppressed to a low value of 10 ² to 10 ⁵ pieces / cm ² . As the result shows, the site X in FIG. 14 and FIG.
Reference numeral 1 denotes a portion where the dislocation density is higher than that of the surrounding area, and is referred to as a "dislocation concentrated region" in the present specification. A portion X2 in FIG. 17 is a portion where the dislocation concentrated region X1 is exposed on the surface.

Further, the n-type GaN substrate 10 was irradiated with ultraviolet rays, and fluorescence emission from the surface was observed using a microscope (fluorescence microscope observation). As a result of the observation, there is a relatively clear boundary in the center of the region sandwiched by the dislocation concentrated regions X1,
It was confirmed that there were stripes of light emission with different contrasts from the surroundings. This luminescent part had a stronger fluorescence emission intensity than the surroundings, and was slightly yellowish and brightly observed. This portion is {0001} during the crystal growth of the n-type GaN layer 22.
The surface corresponds to the portion 25 (FIG. 14) that was growing while being exposed, and is the portion Y2 in FIG.

The width of this portion has some fluctuation, but it was about 30 μm in a wide area. The reason why the width fluctuates is considered to be that the growth of the convex portions 25 does not always proceed uniformly during the crystal growth of the n-type GaN 22.
Further, it is presumed that the reason why the fluorescence emission is observed differently from the surroundings is that the degree of incorporation of the dopant is different from the surroundings.

The portion showing the different fluorescence emission is
It may be hardly formed depending on the manufacturing conditions of the ingot and the positional relationship (distance from the support base 21) in the ingot of the wafer to be cut out. Due to these facts, the site Y2 is referred to as a “high luminescence region” in the present specification. The high luminescence region is n-type Ga.
In FIGS. 14 and 16 showing the cross section of the N substrate 10, a portion Y1
Corresponds to.

The semiconductor laser device of each of the embodiments described below has a laminated structure of a group III nitride semiconductor provided on the n-type GaN substrate having the dislocation concentrated region X1 and the high luminescence region Y1 as described above. In particular, the presence of the dislocation concentrated region X1 is taken into consideration. It should be noted that in each of the embodiments, the substrate in which the SiO ₂ mask is formed in the form of periodic stripes having a pitch of 400 μm is used. Therefore, both the dislocation-concentrated region X1 and the high luminescence region Y1 are present at a pitch of 400 μm.

<First Embodiment> The structure of a semiconductor laser device 1 according to the first embodiment is schematically shown in the longitudinal sectional view of FIG. 3, and the layer structure in the middle of its manufacturing process is shown in FIGS. It is schematically shown in the longitudinal sectional view. In each figure,
The dislocation concentration region X1 and the high luminescence region Y1 of the substrate are also shown.

The semiconductor laser device 1 was manufactured as follows. First, the n-type GaN substrate 1 manufactured as described above
00, MOCVD (Metalorganic Chemical Vapor
3 μm n-type GaN layer 10 using the Deposition method.
2, 40 nm n-type In _0.07 Ga _0.93 N crack prevention layer 103, 1.2 μm n-type Al _0.1 Ga _0.9 N cladding layer 104, _0.1 μm n-type GaN optical guide layer 105, 4
nm In _0.1 Ga _0.9 N well layer and 8 nm In _0.01 Ga
Triple quantum well active layer 106 (barrier layer / well layer / barrier layer / well layer / barrier layer / well layer / barrier layer) consisting of a _0.99 N barrier layer, 20 nm p-type Al _0.3 Ga _0.7 N carrier block layer 107, 0.1 μm p-type GaN light guide layer 10
8, 0.5 μm p-type Al _0.1 Ga _0.9 N cladding layer 10
9, 0.1 μm p-type GaN first contact layer 110,
50 nm p-type In _0.15 Ga _0.85 N second contact layer 1
11 was sequentially crystal-grown to form a laminated structure 101 (FIG. 1).

This group III nitride semiconductor laminated structure 101
When the cross section of the above was observed by a transmission electron microscope, it was found that a region in which dislocations (defects) were concentrated might exist inside the laminated structure 101. The region where the dislocations are concentrated is located above the dislocation concentrated region X1 of the n-type GaN substrate 100, and the p-type InGaN is formed from the lower surface of the n-type GaN layer 102.
The upper surface of the second contact layer 111 was reached. In addition, when the cross section of the laminated structure 101 was observed by a fluorescence microscope, it was found that there are cases where there is a region where the fluorescence emission intensity is stronger than the surroundings and a little yellowish and bright is observed. This region of strong fluorescence emission is located above the high luminescence region Y1 of the substrate 100, and again the n-type GaN layer 102.
Has reached the upper surface of the p-type InGaN second contact layer 111.

The region where dislocations are concentrated and the region where the fluorescence emission is strong inside the laminated structure 101 are the dislocation concentrated regions X of the substrate 100.
1 and the high luminescence region Y1 respectively,
It is considered that this is caused by the influence of the dislocation concentrated region X1 and the high luminescence region Y1. Hereinafter, a region where dislocations are concentrated inside the laminated structure 101 is referred to as a “dislocation concentrated region” similarly to that of the substrate 100 and is represented by X3.
The region of strong fluorescence emission inside 01 is referred to as a “high luminescence region” similarly to that of the substrate 100 and is represented by Y3.

When the dislocation-concentrated region X3 exists, if the laser light waveguide region is provided without considering its position,
The laser light waveguide region includes the dislocation concentration region X3, and naturally the characteristics are not good. Also,
A current easily flows in the dislocation concentrated regions X3 and X1 and when the electrodes touch the exposed defect concentrated regions X3 and X1, the operating current is increased. Further, when the electrode provided on the stacked structure 101 contacts the exposed dislocation concentrated region X3, the metal that is the material of the electrode easily diffuses into the stacked structure 101 through the dislocation concentrated region X3, and the stacked structure 101
Changes the characteristics of each layer. I on GaN substrate
In the conventional semiconductor laser device manufactured by stacking group II nitride semiconductors, the phenomenon that the operating current gradually increases or the characteristics suddenly deteriorate was observed. high.

Therefore, the semiconductor laser device 1 of the present embodiment
Then, as described below, the laser light waveguide region is provided at a position distant from the dislocation concentration region X3, and the electrode is also provided at a position distant from the dislocation concentration region X3 and the dislocation concentration region X1. Since the high luminescence region Y3 also has characteristics different from the surroundings and is not suitable for providing the laser light guiding region, the laser light guiding region should be provided at a position distant from the high luminescence region Y3. ing.

The dislocation concentrated region X3 and the high luminescence region Y3 do not always occur inside the laminated structure 101. As will be described later, when the semiconductor laser device is divided into chips, the dislocation concentrated region X3 and the high luminescence region Y3 can be cut so as not to exist inside the chip. These are shown in FIGS. 1-3, assuming that a high luminescence region Y3 has occurred.

After forming the laminated structure 101 shown in FIG.
As shown in FIG. 2, the dislocation concentration region X1 of the substrate 100
A ridge structure is formed above the center of the luminescence region Y1.
Were periodically formed. The lower part of this ridge structure is
Laser light guide region. The ridge structure is
From the top surface of the p-type second contact layer 111, the p-type cladding layer
We dig up to the middle of 109 by dry etching,
Al on the part removed by etching_0.1Ga_0.9N layer 112
Was regrown and embedded. Below, re-formation
Lengthened Al_0.1Ga_0.9The N layer 112 is called a buried layer
U In addition, Al_{0. 1}Ga_0.9The N buried layer 112 is n-type
May be i-type.

After that, the p-type electrode 113 and the n-type electrode 114 are formed by using the lift-off technique or the etching technique.
Was formed. At that time, as shown in FIG. 3, the electrodes 113,
114 was formed at a position deviating from above and below the dislocation concentration region X1 of the substrate 100.

In the semiconductor laser device 1 thus obtained, the laser light guiding region is located at the center of the dislocation concentrated region X3 and the high luminescence region Y3 of the laminated structure 101, and thus has excellent characteristics. . Further, even if the dislocation-concentrated region X3 of the stacked structure 101 reaches the upper surface of the buried layer 112 and is exposed, the p-type electrode 113 does not come into contact with this and the current flowing between the electrode 113 and the dislocation-concentrated region X3. Does not occur, and the diffusion of the metal material of the electrode 113 into the laminated structure 101 is also suppressed. Although the dislocation concentrated region X1 is exposed on the lower surface of the substrate 100, the n-type electrode 11
4 does not come into contact with this, and no current flows between the electrode 114 and the dislocation concentrated region X1. Therefore, in the semiconductor laser device 1, increase in operating current and deterioration of the laser light guiding region due to this are less likely to occur, stable operating characteristics are obtained, and the laser oscillation life is extended.

In the fabrication of the semiconductor laser device 1, the dislocation concentration region X3 of the laminated structure 101 or the high luminescence region Y3 itself, not the dislocation concentration region of the substrate 100, is used as a reference for the positions of the laser light guiding region and the electrodes 113 and 114. The region X1 and the high luminescence region Y1 are adopted. Dislocation concentrated region X3 and high luminescence region Y of the laminated structure 101
Since 3 is located above the dislocation-concentrated region X1 and the high luminescence region Y1 of the substrate 100, the laser light waveguide region and the electrodes 113 and 114 can be set to desired positions also in this way. In addition, the dislocation concentration region X of the substrate 100
The positions of 1 and the high luminescence region Y1 can be specified from the position of the SiO ₂ mask provided when the substrate 100 was manufactured.

The positions of the dislocation-concentrated region X3 and the high luminescence region Y3 of the laminated structure 101 may be confirmed by observing with a microscope or the like, and the positions of the laser light waveguide region and the electrodes 113 and 114 may be directly determined with reference to these. However, it is more efficient to use the positions of the dislocation concentration region X1 and the high luminescence region Y1 of the substrate 100 as a reference. When the dislocation-concentrated region X3 and the high-luminescence region Y3 are not generated, it is meaningless to set the positions of the laser light waveguide region and the electrodes 113 and 114 as described above, but they are generated. For the sake of convenience, it is preferable that the laser light guiding region and the electrodes 113 and 114 are always set at positions deviating from above and below the dislocation concentrated region X1 and the high luminescence region Y1 of the substrate 100.

When the etching technique is used to form the electrodes 113 and 114, a p-type electrode or an n-type electrode is once formed on the entire upper surface of the buried layer 112 or the lower surface of the n-type GaN substrate 10, and then a predetermined amount is formed. The part is removed by etching. Therefore, the dislocation-concentrated regions X3 and X1 are once covered with the electrode metal. However, since the diffusion phenomenon of the electrode metal into the semiconductor layer through the dislocation-concentrated region X3 described above mainly occurs at the time of energization after completion of the device structure, the dislocation-concentrated region X3 is not covered once during the electrode formation process. However, there is no problem in device characteristics.

As can be seen from FIG. 3, the semiconductor laser device 1 has a structure in which the dislocation-concentrated region X3 is driven outside the periphery of the ridge structure, which is important as a device structure. Therefore, when the semiconductor laser device is divided into chips, the dislocation concentrated region X3 may be used as a boundary for cutting. Since the dislocation concentrated region X3 has a mechanical strength inferior to that of the surroundings, even a group III nitride semiconductor having high hardness can be easily divided. If the portion of the dislocation concentration region X3 exposed on the divided end face is removed by wet etching, polishing, or the like, the leak current flowing through the edge portion of the chip can be suppressed, which is highly effective in improving the device characteristics. Alternatively, by dividing the dislocation-concentrated region X3 itself from the inside of the chip by dividing the dislocation-concentrated region X3 between the ridge structure and the dislocation-concentrated region X3, a leak current flowing through the dislocation-concentrated region X3 can be prevented in advance. .

<Second Embodiment> The structure of a semiconductor laser device 2 of the second embodiment is schematically shown in the vertical sectional view of FIG. 5, and the layer structure in the middle of its manufacturing process is shown in the vertical sectional view of FIG. Is schematically shown in. Semiconductor laser device 2 of this embodiment
Modify the semiconductor laser device 1 of the first embodiment to
A dielectric film 115 is provided on the upper surface of the buried layer 112 above the dislocation concentration region X1 of the n-type GaN substrate 100 and on the lower surface of the substrate 100 below the dislocation concentration region X1. Is. n-type GaN substrate 1
No. 00 and the laminated structure 101 are similar in configuration and manufacturing method to those of the first embodiment, and duplicate explanations are omitted.

The dielectric film 115 was formed using SiO ₂ by the photolithography process and the lift-off process after forming the ridge structure as shown in FIG. 2 (FIG. 4). The dielectric film 115 has a width of 50 μm and a film thickness of 25.
It is 0 nm. The width of the dislocation-concentrated region X3 generated inside the stacked structure 101 is approximately equal to the width of the dislocation-concentrated region X1 in the substrate 100, which is 5 to 40 μm.
Even if the dislocation concentrated region X3 is exposed, the dielectric film 115 on the upper surface covers the entire dislocation concentrated region X3, and the dielectric film 115 on the lower surface of the substrate 100 is formed.
Also covers the entire dislocation concentrated region X1 exposed.

After forming the dielectric film 115, the dielectric film 11 is formed.
5, the p-type electrode 116 is formed on the entire upper surfaces of the p-type second contact layer 111 and the buried layer 112 having the ridge structure,
An n-type electrode 117 was formed on the entire lower surface of the n-type GaN substrate 100 (FIG. 5).

The electrodes 116 and 117 are separated from the dislocation-concentrated region X3 and the dislocation-concentrated region X1 by the dielectric film 115, and between the electrode 116 and the dislocation-concentrated region X3 and between the electrode 117 and the dislocation-concentrated region X1. There is no current flowing, and the material metal of the electrode 116 does not diffuse inside the stacked structure 101 via the dislocation concentrated region X3. Therefore, the semiconductor laser device 2 also exhibits stable operation characteristics,
The device has a long laser oscillation life.

The material of the dielectric film 115 is S
In addition to iO ₂ , SiN, SiO, ZnO, PbO, Ti
O ₂ , ZrO ₂ , CeO ₂ , HfO ₂ , Al ₂ O ₃ , Bi
₂ O ₃ , Cr ₂ O ₃ , In ₂ O ₃ , Nd ₂ O ₃ , Sb ₂ O ₃ , Ta
₂ O ₅ , Y ₂ O ₃ , AlF ₃ , BaF ₂ , CeF ₂ , CaF ₂ ,
MgF ₂ , NdF ₃ , PbF ₂ , SrF ₂ , ZnS, ZnS
e, etc., or a mixture thereof can also be used.

The dielectric film 115 has a thickness of 1 nm to
It may be in the range of 1 μm, more preferably in the range of 5 nm to 500 nm. If the film thickness is less than 1 nm, the effect of blocking current or preventing metal diffusion may become insufficient, or dielectric breakdown may occur when a voltage is applied, which is not preferable. Further, if the film thickness is larger than 1 μm, the stress in the dielectric film becomes large, and the film is likely to be cracked or peeled off, which is also not preferable.

Regarding the width of the dielectric film 115, it is sufficient to completely cover the exposed portions of the dislocation-concentrated regions X3 and the dislocation-concentrated regions X1. Although there is a lower limit for this,
There is no particular upper limit. However, if the width of the dielectric film 115 is excessively increased, it may interfere with the current to be guided to the laser light guiding region, and in order to avoid this, the position where the laser light guiding region is provided is restricted. Therefore, the width of the dielectric film 115 is preferably 5 to 300 μm.

<Third Embodiment> The structure of a semiconductor laser device 3 according to a third embodiment is schematically shown in the vertical cross-sectional view of FIG. 8, and the layer structure in the middle of its manufacturing process is shown in FIGS. 6 and 7. It is schematically shown in the longitudinal sectional view. The semiconductor laser device 3 according to the present embodiment is modified from the semiconductor laser device 1 according to the first embodiment, and the n-type GaN substrate 1 in the inside of the laminated structure 101 is modified.
No. 00, the dielectric film 118 is provided in a region located above the dislocation concentration region X1. Other configurations of the laminated structure 101 are similar to those of the first embodiment.

The dielectric film 118 is in the process of forming a ridge structure.
Formed in. That is, as described above, the p-type second capacitor
From the top surface of the tact layer 111 to the middle of the p-type cladding layer 109.
With dry etching, p-type Al_0.1G
a_0.9When the N layer 109 is exposed (FIG. 6), the substrate 1
00 in a region located above the dislocation concentration region X1
₂A film 118 is formed, and then Al is formed around the ridge structure._0.1G
a_0.9N buried layer 112 was regrown and buried
(Fig. 7).

After forming the dielectric film 118 and the ridge structure, the p-type electrode 116 is formed on the entire upper surfaces of the p-type second contact layer 111 and the buried layer 112 having the ridge structure, and the dislocations in the lower surface of the n-type GaN substrate 100 are formed. The n-type electrode 114 was formed in a portion other than the portion located below the concentrated region X1 (FIG. 8).

By providing the dielectric film 118, Al
The dislocation concentration region X3 does not affect the epitaxial growth of the GaN burying layer 112, and the dislocation concentration region does not occur in the burying layer 112. For this reason, the leak current flowing in the region other than the laser light guiding region is reduced, and the diffusion of the material metal of the electrode 116 into the laminated structure 101 is also suppressed. Therefore, the semiconductor laser device 3 also exhibits stable operation characteristics and has a long laser oscillation life.

Although the dielectric film 118 is formed on the etching bottom surface of the ridge structure here, it may be provided on another interface. For example, n-type InGaN crack prevention layer 10
It can also be provided at the interface between the n-type AlGaN cladding layer 104 and the n-type AlGaN cladding layer 104. However, as in the present embodiment, the dielectric film 11
8 is formed on the bottom surface of the ridge structure, the semiconductor layer can be regrown once, and the crystallinity of the semiconductor laser element is improved. It is preferable because it is difficult. For the material, thickness and width of the dielectric layer 118:
What has been described in the second embodiment is directly applicable.

<Fourth Embodiment> The structure of a semiconductor laser device 4 according to a fourth embodiment is schematically shown in the vertical cross-sectional view of FIG. 10, and the layer structure during the manufacturing process thereof is shown in the vertical cross-sectional view of FIG. Is schematically shown in. Semiconductor laser device 4 of this embodiment
Modify the semiconductor laser device 1 of the first embodiment to
A dielectric film 119 of SiO ₂ is provided on a portion of the upper surface of the n-type GaN substrate 100 located above the dislocation concentration region X1. The dielectric film 119 is provided on the substrate 100 before forming the laminated structure 101 (FIG. 9). The manufacturing process and configuration of the laminated structure 101 are similar to those of the first embodiment.

By providing the dielectric film 119 on the substrate 100, the morphology of the portion of the n-type GaN layer 102 above and around the dielectric film 119 is slightly reduced,
The dislocation-concentrated region X1 of the substrate 100 does not affect the epitaxial growth of the GaN layer 102 and the layers above the GaN layer 102, and the dislocation-concentrated region does not occur in the stacked structure 101. Therefore, even if the p-type electrode 116 is provided on the entire upper surface of the laminated structure 101 or the n-type electrode 117 is provided on the entire lower surface of the substrate 100, a leak current does not occur, and the laminated structure of the material metal of the p-type electrode 116 is formed. Diffusion into 101 is also prevented. Therefore, the semiconductor laser device 4 also exhibits stable operation characteristics and has a long laser oscillation life. The material, thickness, and width of the dielectric layer 119 are the same as those described in the second embodiment.

<Fifth Embodiment> The structure of a semiconductor laser device 5 according to the fifth embodiment is schematically shown in the vertical cross-sectional view of FIG. 12, and the layer structure during the manufacturing process thereof is shown in the vertical cross-sectional view of FIG. Is schematically shown in. Semiconductor laser device 5 of this embodiment
Modify the semiconductor laser device 1 of the first embodiment to
A dielectric is used instead of AlGaN as a material for filling the periphery of the ridge structure, and the dielectric layer 122 is provided on the p-type AlGaN cladding layer 109.

After forming the dielectric layer 122 (FIG. 11), the p-type second contact layer 111 having a ridge structure and the dielectric layer 122 are formed.
The p-type electrode 116 was formed on the entire upper surface of the n-type GaN substrate 100, and the n-type electrode 114 was formed on the lower surface of the n-type GaN substrate 100 except the portion located below the dislocation concentrated region X1 (FIG. 12).

In the semiconductor laser device 5 of this embodiment, even if the dislocation concentrated region X3 is generated inside the laminated structure 101,
The dislocation concentrated region X3 is blocked by the dielectric layer 122 and does not reach the p-type electrode 116. Therefore, like the semiconductor laser devices 1 to 4, the device exhibits stable operation characteristics and has a long laser oscillation life.

Comparative Example A semiconductor laser device 9 of a comparative example was manufactured by using the layer structure in the process of manufacturing the semiconductor laser device 1 of the first embodiment shown in FIG. The structure of this semiconductor laser device 9 is schematically shown in the vertical sectional view of FIG. The p-type electrode 212 is formed on the substrate 10 on the upper surface of the laminated structure 101.
0 is provided over a wide range from a region located above the dislocation-concentrated region X1 to a region located above the high-luminescence region Y1. The n-type electrode 213 is also provided on the lower surface of the substrate 100 and has the dislocation-concentrated region X1. Is provided in a wide range from a portion located below the high luminescence region Y1 to a portion located below the high luminescence region Y1.

A light emission test was conducted on many samples of the semiconductor laser devices 1 to 5 of the respective embodiments and the semiconductor laser device 9 of the comparative example. As a result, it was found that the semiconductor laser device 9 was 100 ° C. under the conditions of 60 ° C. and 30 mW. The phenomenon in which the operating current increased within the time appeared in some of the samples, and the number of samples whose laser oscillation life exceeded 1000 hours was about half. On the other hand, in the semiconductor laser devices 1 to 5 of each embodiment, under the same conditions, the increase in operating current did not appear for 1000 hours or longer, and most of the samples exhibited a laser oscillation life of 3000 hours or longer. Thus, the presence of dislocation-concentrated regions in the group III nitride semiconductor substrate greatly affects the characteristics of the group III nitride semiconductor device, and the configurations of the respective embodiments are useful for improving the characteristics of the group III nitride semiconductor device. It was confirmed.

The configurations of the above-described first to fifth embodiments are not limited to those shown in each embodiment, but can be freely combined. As an example, the configuration of the first embodiment in which the p-type electrode is patterned without providing the dielectric film on the contact layer, and the second embodiment in which the dielectric film is provided on the lower surface of the substrate to form the n-type electrode on the entire surface. The configuration of the embodiment of
Can be combined.

In the first to fifth embodiments,
The position of the ridge structure, that is, the position of the laser light guiding region is set above the center of the dislocation concentrated region X1 and the high luminescence region Y1, but it may be located closer to either one.
It suffices that neither the dislocation-concentrated region X3 nor the high-luminescence region Y3 is substantially included in the ridge structure portion. Further, the current injection portion on the laminated structure side is not limited to the ridge structure, and may be an electrode stripe type or a BH type.

Further, in the first embodiment, the electrodes 113, 1
14 positions, the dielectric layer 11 in the second to fifth embodiments.
The existence and position of 5, 118, 119 and 122 are important, and the structure and composition of other layers can be freely set. For example, in each embodiment, the p-type contact layer has a two-layer structure of the first contact layer and the second contact layer, but the contact layer may be one layer. As for the electrodes, any material may be used as long as it is an ohmic electrode compatible with the group III nitride semiconductor. For example, as the p-type electrode, Au / Pd (Pd is the semiconductor side), Au / Mo / Pd, Au / Pt / Pd, Au
/ Pt / Mo / Pd, Au / Ni, Au / Mo / Ni /
Al / Hf, Al / T as P-type electrodes such as Pd
i, Al / Hf / Ti, Al / Zr, etc. can be adopted.

[0072]

In the semiconductor laser device of the present invention, the laser light guide region has good characteristics, and the operating current increases due to the presence of dislocation concentrated regions in the substrate and the deterioration due to the diffusion of the metal material of the electrode. Therefore, the operating characteristics are stable and the laser oscillation life is extended.

If the electrodes provided on the upper surface of the laminated structure and the electrodes provided on the lower surface of the substrate are located only above and below the low dislocation region of the substrate, the operating current increases and the material metal No special consideration is required for the prevention of diffusion, and the laminated structure can be easily manufactured. Even if the current blocking layer is provided on the upper surface of the laminated structure above the dislocation concentrated region and on the lower surface of the substrate below the dislocation concentrated region, the steps up to the step of forming the current blocking layer Since it is not necessary to consider increase of operating current and prevention of diffusion of material metal, it is easy to manufacture a laminated structure. Further, when the current blocking layer is provided in the portion of the laminated structure located above the dislocation concentration region of the substrate, it is not necessary to consider the increase of the operating current and the prevention of the diffusion of the material metal when forming the electrode. , There is no restriction on the shape of the electrode.

When the dislocation-concentrated region of the substrate has a stripe shape which is substantially parallel to the laser light guiding region of the laminated structure when viewed from above, the laminated structure including the formation of the laser light guiding region can be easily manufactured, and the electrode It also facilitates the formation of the current blocking layer.

The thickness of the current blocking layer is 1 nm or more and 1 μm.
In the case of the following, it is possible to reliably prevent an increase in operating current, and there is less risk that mechanical defects such as cracks and peeling will occur.

When the dislocation-concentrated region is formed in a stripe shape substantially parallel to the laser light guiding region and the width of the current blocking layer is 5 μm or more and 300 μm or less, an increase in operating current can be reliably prevented and the current can be prevented. It is easy to avoid that the blocking layer interferes with the current to be guided to the laser light guiding region.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing a layer structure during a manufacturing process of a semiconductor laser device according to a first embodiment.

FIG. 2 is a vertical cross-sectional view schematically showing a layer structure during a manufacturing process of the semiconductor laser device according to the first embodiment.

FIG. 3 is a vertical sectional view schematically showing the structure of the semiconductor laser device according to the first embodiment.

FIG. 4 is a vertical cross-sectional view schematically showing a layer structure during a manufacturing process of the semiconductor laser device according to the second embodiment.

FIG. 5 is a longitudinal sectional view schematically showing the structure of the semiconductor laser device according to the second embodiment.

FIG. 6 is a vertical cross-sectional view schematically showing a layer structure during a manufacturing process of a semiconductor laser device according to a third embodiment.

FIG. 7 is a vertical cross-sectional view schematically showing the layer structure during the manufacturing process of the semiconductor laser device according to the third embodiment.

FIG. 8 is a vertical sectional view schematically showing the structure of a semiconductor laser device according to a third embodiment.

FIG. 9 is a vertical cross-sectional view schematically showing the layer structure during the manufacturing process of the semiconductor laser device according to the fourth embodiment.

FIG. 10 is a vertical sectional view schematically showing the structure of a semiconductor laser device according to a fourth embodiment.

FIG. 11 is a vertical cross-sectional view schematically showing the layer structure during the manufacturing process of the semiconductor laser device according to the fifth embodiment.

FIG. 12 is a vertical sectional view schematically showing the structure of a semiconductor laser device according to a fifth embodiment.

FIG. 13 is a vertical sectional view schematically showing the structure of a semiconductor laser device of a comparative example.

FIG. 14 is a vertical cross-sectional view schematically showing an enlarged part of the GaN substrate being manufactured.

FIG. 15 is a perspective view schematically showing the entire GaN substrate being manufactured.

FIG. 16 is a vertical cross-sectional view of a part of a GaN substrate.

FIG. 17 is a top view of a portion of a GaN substrate.

[Explanation of symbols]

1, 2, 3, 4, 5 Semiconductor Laser Element 10 n-type GaN Substrate 21 Supporting Substrate 22 n-type GaN Layer 23 {11-22} Facet Face 24 Bottom of Concavity 25 {0001} Face 100 n-type GaN Substrate 101 III Group nitride semiconductor laminated structure 102 n-type GaN layer 103 n-type In _0.07 Ga _0.93 N crack prevention layer 104 n-type Al _0.1 Ga _0.9 N cladding layer 105 n-type GaN optical guide layer 106 In _0.1 Ga _0.9 N / In _0.01 Ga _0.99 N3 quantum well active layer 107 p-type Al _0.3 Ga _0.7 N carrier block layer 108 p-type GaN optical guide layer 109 p-type Al _0.1 Ga _0.9 N cladding layer 110 p-type GaN first contact layer 111 p-type In _0.15 Ga _0.85 N the second contact layer 112 Al _0.1 Ga _0.9 n buried layer 113 and 116 p-type electrode 114 and 117 n-type electrode 115,1 8,119 SiO ₂ film 122 SiO ₂ layer X1 dislocation concentrated region Y3 layered structure of the high luminescent region Y2 high luminescent region exposed portion X3 laminated structure of the substrate of the dislocation-concentrated region exposed portion Y1 substrate dislocation concentrated region X2 substrate of the substrate High luminescence region of

Continued front page    (72) Inventor Shigetoshi Ito             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Takayuki Yuasa             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Mototaka Tanetani             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Kensaku Motoki             Sumitomo, 1-1 1-1 Koyokita, Itami City, Hyogo Prefecture             Electric Industry Co., Ltd. Itami Works F-term (reference) 5F073 AA13 AA45 AA47 AA51 AA61                       AA74 CA07 CB02 DA05 DA07                       EA27

Claims (8)

[Claims] 1. A substrate made of a group III nitride semiconductor,
What is claimed is: 1. A semiconductor laser device comprising: a laminated structure made of a group III nitride semiconductor provided on the upper surface of a substrate; and an electrode provided on the upper surface of the laminated structure. And a low-dislocation region that is a region excluding the region, the laminated structure has a laser-waveguide region in a stripe shape located only above the low-dislocation region of the substrate, and the electrode exists only above the low-dislocation region of the substrate. A semiconductor laser device characterized by being positioned. 2. A substrate made of a group III nitride semiconductor,
What is claimed is: 1. A semiconductor laser device comprising: a laminated structure made of a group III nitride semiconductor provided on the upper surface of a substrate; and an electrode provided on the lower surface of the substrate. And a low-dislocation region that is a part except for, the laminated structure has a stripe-shaped laser light guiding region located only above the low-dislocation region of the substrate, and the electrode is located only below the low-dislocation region of the substrate. A semiconductor laser device characterized by: 3. A substrate made of a group III nitride semiconductor,
A semiconductor laser device having a laminated structure made of a group III nitride semiconductor provided on an upper surface of a substrate, comprising: The laminated structure has a stripe-shaped laser light waveguide region located only above the low dislocation region of the substrate, and the portion of the lower surface of the substrate located below the dislocation concentrated region A semiconductor laser device, comprising: a current blocking layer provided on a portion of the substrate located above the dislocation concentration region. 4. A substrate made of a group III nitride semiconductor,
A semiconductor laser device having a laminated structure made of a group III nitride semiconductor provided on the upper surface of a substrate, wherein a dislocation concentrated region where the substrate reaches the upper surface from the lower surface and a low dislocation region which is a portion excluding the dislocation concentrated region are formed. The laminated structure has a stripe-shaped laser light guiding region located only above the low dislocation region of the substrate, and the current blocking layer is provided inside the laminated structure above the dislocation concentration region of the substrate. A semiconductor laser device comprising: 5. The dislocation concentration region of the substrate is viewed from above,
The semiconductor laser device according to any one of claims 1 to 4, wherein the semiconductor laser device has a stripe shape that is substantially parallel to a laser light guiding region of a laminated structure. 6. The current blocking layer is SiO ₂ , SiN, Si
O, ZnO, PbO, TiO ₂ , ZrO ₂ , CeO ₂ , H
fO ₂ , Al ₂ O ₃ , Bi ₂ O ₃ , Cr ₂ O ₃ , In ₂ O ₃ , N
d ₂ O ₃ , Sb ₂ O ₃ , Ta ₂ O ₅ , Y ₂ O ₃ , AlF ₃ , Ba
F ₂ , CeF ₂ , CaF ₂ , MgF ₂ , NdF ₃ , PbF ₂ ,
At least one of SrF ₂ , ZnS, and ZnSe
4. A dielectric comprising a type,
The semiconductor laser device according to claim 5, wherein claim 4 or any one of claim 3 or claim 4 is cited. 7. The current blocking layer has a thickness of 1 nm or more and 1 μm.
6. The semiconductor laser device according to claim 5, wherein m or less, claim 3, claim 4, or claim 3 or claim 4 cited. 8. The width of the current blocking layer is 5 μm or more and 300.
The semiconductor laser device according to claim 5, wherein the semiconductor laser device has a thickness of not more than μm.