JP4072351B2 - Nitride compound semiconductor light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nitride-based compound semiconductor device, and more specifically, a semiconductor crystal substrate having a high-density defect region penetrating the substrate in a periodic arrangement on the substrate surface as a region where the crystal defect density is higher than the surroundings. A nitride-based compound semiconductor device having a nitride-based compound semiconductor multilayer structure on the top, one electrode on the back side of the substrate, and the other electrode on the multilayer structure, and nitriding using a high-density defect region The present invention relates to a physical compound semiconductor device.
[0002]
[Prior art]
Nitride compound semiconductors (hereinafter referred to as nitride compound semiconductors) such as GaN, AlGaN, GaInN, AlGaInN, and AlBGaInN generally have band gap energy compared to III-V group compound semiconductors such as AlGaInAs and AlGaInP. Eg is large and it is a direct transition semiconductor.
Due to this feature, these nitride-based compound semiconductors are used as materials for producing semiconductor light-emitting elements such as semiconductor laser elements and light-emitting diodes (LEDs) that emit light in the short wavelength range from the ultraviolet region to the red region. Attention has been paid.
These semiconductor light-emitting elements are being widely applied as light sources for recording / reproducing optical pickups of high-density optical disks, light-emitting elements for full-color displays, and other light-emitting devices in fields such as environment and medicine.
[0003]
These nitride-based compound semiconductors have, for example, a high saturation rate of GaN in a high electric field region, or a nitride-based compound semiconductor is insulated as a semiconductor layer when forming a MIS (Metal-Insulator-Semiconductor) structure. A feature is that aluminum nitride (AlN) is used as the layer, and the semiconductor layer and the insulating layer can be continuously crystal-grown.
Due to this feature, nitride-based compound semiconductor devices are attracting attention as electronic devices that have high saturation drift speed and electrostatic breakdown voltage, and are excellent in high-speed operability, high-speed switching performance, large current operability, and the like.
[0004]
In addition, nitride compound semiconductors are (1) more highly conductive than GaAs, etc., and are therefore more advantageous as materials for high-power devices at high temperatures than GaAs. (2) Chemically stable materials In addition, since it has high hardness, it can be evaluated as a highly reliable element material.
[0005]
In general, when a semiconductor film is grown on a substrate, a bulk substrate similar to the growth film or having a lattice constant close to that is used as the substrate. Therefore, in the case of a nitride-based semiconductor element, for example, a GaN substrate made of the same nitride-based semiconductor is desirable. However, a GaN substrate is manufactured in a small size under ultra-high pressure and ultra-high temperature. Therefore, it is extremely difficult to produce a substrate having a large size practically.
SiC substrates, ZnO substrates, and MgAl ₂ O ₄ substrates have also been used as substrates for nitride-based semiconductor devices, but in general, nitride-based semiconductor devices are most often fabricated on sapphire substrates.
[0006]
The sapphire substrate is supplied with a high quality, low cost, and a size of 2 inches or more. However, the sapphire substrate has a problem of large lattice mismatch and a large difference in thermal expansion coefficient from GaN, which is a typical nitride semiconductor. In addition, the sapphire substrate is not cleaved, has low electrical conductivity, and is electrically insulated.
For example, since the lattice mismatch between sapphire and GaN is about 13%, which is large, a buffer layer is provided between the sapphire substrate and the GaN layer to alleviate the mismatch, and a good single crystal GaN layer is epitaxially grown. However, the defect density reaches, for example, about 10 ⁸ to 10 ⁹ cm ⁻² , which adversely affects the operation reliability of the semiconductor element.
[0007]
(1) Since the difference in thermal expansion coefficient between the sapphire substrate and the GaN layer is large, if the crystal growth film is thick, the warpage of the substrate becomes large even at room temperature, and there is a concern about the occurrence of cracks. (2) The sapphire substrate has no cleaving property and it is difficult to stably form a laser facet with high specularity. Furthermore, (3) sapphire is insulative, so GaAs It is difficult to provide one electrode on the back surface of the substrate as in a semiconductor laser device, and it is necessary to provide both the p-side electrode and the n-side electrode on the nitride compound semiconductor laminated structure side on the substrate. Becomes wider and the process becomes complicated.
[0008]
In view of this, research has been actively conducted to produce a nitride compound semiconductor, in particular, a GaN single crystal substrate lattice-matched with a GaN compound semiconductor by an industrially easy method.
As one of them, for example, Japanese Patent Application Laid-Open No. 2001-102307 discloses that a growth surface of vapor phase growth is not in a flat state but has a three-dimensional facet structure, and the facet structure is embedded while the facet structure is maintained. Disclosed is a crystal growth method for single-crystal gallium nitride in which dislocations are reduced by growing without crystal.
According to this method, a GaN single crystal layer can be produced by growing a GaN single crystal layer on a GaAs substrate through a windowed mask and slicing the grown GaN single crystal layer.
[0009]
[Problems to be solved by the invention]
By the way, a semiconductor element such as a nitride-based compound semiconductor element is an element capable of increasing the functionality and new functions of the element, for example, changing the wavelength (including wavelength change by frequency modulation), or an element with reduced noise. Etc. are desired.
Then, for example, by utilizing the characteristics of the above-mentioned GaN single crystal substrate or the like, these new functional elements can be manufactured in a simple process and with a small number of processes without complicating the drive power supply of the elements. Have been researched.
[0010]
Accordingly, an object of the present invention is to provide a nitride-based compound semiconductor device having a new function and a structure that can be manufactured with a simple process and a small number of processes by utilizing the characteristics of a semiconductor substrate.
[0011]
[Means for Solving the Problems]
In the course of research to solve the above-mentioned problems, the present inventor has developed GaN developed as a semiconductor substrate having a novel configuration in which high-density defect regions are regularly, for example, periodically arranged in low-density defect regions. We focused on single crystal substrates.
This GaN single crystal substrate has been developed by improving the technique disclosed in Japanese Patent Laid-Open No. 2001-102307 and controlling the position of the high-density defect region generated in the low-density defect region.
[0012]
The arrangement pattern of the high-density defect area of the developed semiconductor substrate can be freely selected. For example, the arrangement pattern of a square lattice as shown in FIG. 4A or the shape of a rectangular lattice as shown in FIG. As shown in FIG. 5B, there are an array and a hexagonal lattice array. 4A and 4B are a plan view and a cross-sectional view of a GaN substrate for explaining the high-density defect region, respectively.
Further, the arrangement pattern of the high-density defect areas is not limited to the distributed pattern as described above. For example, as shown in FIG. In addition, as shown in FIG. 6B, it is possible to produce a structure in which high-density defect regions are continuous in a linear shape.
[0013]
Here, a method for manufacturing a GaN single crystal substrate will be described.
The basic crystal growth mechanism of a GaN single crystal is to grow with a slope consisting of facets, and maintain and maintain the facets slope to propagate the dislocations and collect the dislocations in place. Let The region grown by this facet surface becomes a low defect region due to dislocation movement.
On the other hand, the growth is carried out with a high-density defect region with a clear boundary at the lower part of the facet slope, and dislocations gather at the boundary of the high-density defect region or inside, and disappear here. Or accumulate.
[0014]
The shape of the facet surface varies depending on the shape of the high-density defect region. When the defect area is dot-shaped, the facet surface is surrounded with the dot as the bottom, and a pit composed of the facet surface is formed.
In addition, when the defect region has a stripe shape, it becomes a triangular prism-shaped facet surface that has a stripe as a valley bottom, has facet inclined surfaces on both sides thereof, and lies sideways.
[0015]
This dense defect area can have several states. For example, it may be made of polycrystal. Moreover, although it is a single crystal, it may be slightly inclined with respect to the surrounding low defect area | region. In addition, the C axis may be inverted with respect to the surrounding low defect area. Thus, this high density defect area has a clear boundary and is distinguished from the surroundings.
By growing with this high defect density region, the growth can proceed while maintaining the facet surface without embedding the facet surface around the region.
Then, by grinding and polishing the surface of the GaN growth layer, the surface can be flattened and used as a substrate.
[0016]
This method of forming a high-density defect region can be generated by pre-forming seeds in a place where the high-density defect region is to be formed when GaN is grown on a base substrate. . As the seed, an amorphous or polycrystalline layer is formed in a micro region serving as a seed. On top of that, by growing GaN, a high-density defect region can be formed in that kind of region.
[0017]
A specific method for manufacturing the GaN single crystal substrate is as follows. First, a base substrate on which a GaN layer is grown is used. The base substrate is not necessarily specified and may be a general sapphire substrate, but a GaAs substrate or the like is preferable in consideration of removing the base substrate in a later step.
For example, seeds made of, for example, a SiO ₂ layer are regularly and periodically formed on the base substrate. The shape of the seed is a dot shape or a stripe shape according to the arrangement and shape of the high-density defect region.
Thereafter, GaN is grown in a thick film by a Hydrocarbon Vapor Phase Epitaxy (HVPE). After the growth, a facet surface corresponding to the pattern shape of the seed is formed on the surface. For example, when the seed is a dot-like pattern, pits composed of facet surfaces are regularly formed, and when the seed is a stripe shape, a prism-like facet surface is formed.
[0018]
After the GaN layer is grown, the base substrate is removed, and the thick film layer of GaN is ground and polished to flatten the surface. Thereby, a GaN substrate can be manufactured. The thickness of the GaN substrate can be freely set.
The GaN substrate manufactured in this way has a C-plane as a main surface, in which a high defect density region of a predetermined size of dots or stripes is regularly formed. The single crystal region other than the high defect density region is a low dislocation density region in which the dislocation density is significantly lower than that of the high defect density region.
[0019]
The present inventor has made use of the substrate characteristics of the semiconductor substrate having the above-described novel configuration, that is, a region that cannot be handled as a component of a nitride-based compound semiconductor element because of many crystal defects. By utilizing the high-density defect region of the GaN substrate and providing a third electrode and supplying a current between the electrode on the stacked structure and the third electrode, the device characteristics of the nitride-based compound semiconductor device, For example, the inventors conceived of controlling wavelength or noise, and came to invent the present invention after the experiment.
In the above description, the semiconductor laser device has been described as an example, but this applies to all nitride-based compound semiconductor devices.
[0020]
In order to achieve the above object, the nitride-based compound semiconductor device according to the present invention has a high-density defect region penetrating the substrate in a periodic arrangement on the substrate surface as a region where the crystal defect density is higher than the surroundings. A nitride-based compound semiconductor device comprising a nitride-based compound semiconductor multilayer structure on a semiconductor crystal substrate, wherein the first and second electrodes are provided at predetermined positions on the multilayer structure,
The substrate includes a third electrode embedded in a hole provided so as to penetrate or not penetrate the core region substrate having the highest defect density in the high-density defect region,
The device characteristics are controlled by supplying a current between the other electrode and the third electrode.
[0021]
The semiconductor element is an element such as a semiconductor laser element, a semiconductor light emitting diode, or a semiconductor electronic element, and injects a drive current into the laminated structure through two or more electrodes provided at predetermined positions of the laminated structure. Thus, the element exhibits unique element characteristics. The predetermined position of the electrode means an optimum position for improving the performance of the semiconductor element.
[0022]
In the present invention, the diameter of the through hole or blind hole is arbitrary, and there is no restriction as long as the third electrode can be provided in the hole. In addition, it is not always necessary that the hole opened in the core region is a through hole, and it may be a blind hole halfway through the substrate.
The high-density defect region is a columnar region that penetrates the substrate, and the cross-sectional shape of the high-density defect region is arbitrary.
[0023]
The nitride compound semiconductor element of the present invention is a concept including a nitride semiconductor laser element, a nitride semiconductor light emitting diode, a nitride compound semiconductor electronic element, and the like.
The semiconductor crystal substrate is not limited in its composition as long as it has a high-density defect region penetrating the substrate in a periodic arrangement on the substrate surface as a region where the crystal defect density is higher than the surroundings.
The nitride-based compound semiconductor, refers _{Al a B b Ga c In d} N (a + b + c + d = 1,0 ≦ a, b, c, d ≦ 1) a.
[0024]
The nitride compound semiconductor device according to the present invention can control device characteristics such as wavelength, noise, and optical bistability by supplying a current between the other electrode and the third electrode.
The nitride-based compound semiconductor device according to the present invention is a device that has a compact configuration, has an unprecedented function of controlling device characteristics, and can be manufactured by a simple process.
[0025]
The noise of the semiconductor laser element is related to spontaneous emission light and is generated by an unstable oscillation mode or mode competition. Conventionally, in order to reduce noise, a single longitudinal mode is performed by various methods, but a method using high-frequency superposition has been proposed. For example, when a high frequency of several hundred MHz to several GHz is superposed on the driving current of the semiconductor laser element, stable multimode oscillation occurs and mode hopping noise is reduced.
Therefore, in a preferred embodiment of the present invention, when the nitride-based compound semiconductor element is a light emitting element, a driving current is applied between the other electrode and the one electrode, and the other electrode and the third electrode are applied. The high frequency current is applied between the two and the high frequency current is superimposed on the drive current, thereby reducing the noise of the light emitting element. That is, mode hopping noise can be reduced by superimposing high frequency on the third electrode.
[0026]
In another preferred embodiment of the present invention, when the nitride-based compound semiconductor element is an edge emission type light emitting element, a third electrode is provided in contact with the emission end face, and the other electrode, one electrode, And a small current smaller than the driving current is supplied between the other electrode and the third electrode so that the one electrode and the third electrode function as a tandem electrode, and the light emitting element Increases optical bistability.
[0027]
In the laminated structure sandwiched between one electrode and the other electrode of this embodiment, light is amplified by supplying a current from the other electrode to one electrode, while the third electrode is supplied from the other electrode. The light is absorbed in the region near the emission end face by the small current supplied to, thereby becoming a saturable absorber.
When the current supplied from the other electrode to the third electrode is made constant and the drive current is supplied from the other electrode to the one electrode as before, light absorption in the region near the emission end face is large before oscillation, but after oscillation, Since the light absorption in the region near the emission end face is saturated, the threshold current is reduced and hysteresis is generated. Thereby, the optical bistability of a light emitting element can be improved.
[0028]
In the present invention, the arrangement pattern of the high-density defect region is arbitrary, specifically, the high-density defect region is periodically formed on the substrate surface of the semiconductor crystal substrate, for example, a square lattice shape, a rectangular lattice shape, and It may be scattered in any arrangement of a hexagonal lattice.
In addition, the high-density defect regions are linear high-density defect regions that are periodically and spaced apart from each other on the substrate surface of the semiconductor crystal substrate, and the dotted high-density defect regions are The high-density defect area | region which is mutually arrange | positioned or intermittently arrange | positioned at linear form, or the high-density defect area | region where a high-density defect area | region extends linearly continuously may be sufficient.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below specifically and in detail with reference to the accompanying drawings. It should be noted that the film formation method, the composition and thickness of the compound semiconductor layer, the process conditions, and the like shown in the following embodiment examples are merely examples for facilitating understanding of the present invention, and the present invention is not limited to these examples. It is not limited.
Embodiment 1
The nitride-based compound semiconductor device according to the present embodiment is an embodiment in which the nitride-based compound semiconductor device according to the present invention including the third electrode is applied to a nitride-based semiconductor laser device, and FIG. It is sectional drawing which shows the structure of the nitride type semiconductor laser element of the example of this embodiment.
As shown in FIGS. 4A and 4B, the GaN substrate 76 on which the nitride-based semiconductor laser device 10 of this embodiment is formed has a so-called high-density defect region in which the crystal defect density is higher than the surrounding region. 78 has a characteristic that it penetrates the GaN substrate 76 and is present in a square square lattice arrangement on the substrate surface in a plan view. Note that the n-type GaN substrate 12 described next is a part of the GaN substrate 76 as shown in FIG. Reference numeral 80 denotes a laser stripe.
[0030]
As shown in FIG. 1, a nitride-based semiconductor laser device 10 according to the present embodiment includes a 3.0-μm thick Si-doped n-type GaN layer 14 and a 0.5-μm thick Si film on an n-type GaN substrate 12. Multiple layers comprising a doped n-type AlGaN cladding layer 16, a Si-doped n-type GaN optical waveguide layer 18 having a thickness of 0.1 μm, Ga _1-x In _x N (well layer) and Ga _1-y In _y N (barrier layer). 40 nm thick active layer 20 having a quantum well structure, 0.1 μm thick Mg-doped p-type GaN optical waveguide layer 22, 0.5 μm thick Mg-doped p-type AlGaN cladding layer 24, and 0.5 μm thick The Mg-doped p-type GaN contact layer 26 is provided.
[0031]
On the Mg-doped p-type GaN contact layer 26, Pd (palladium), Pt (platinum), Au (gold) are sequentially deposited, and a stripe-shaped p-side electrode 28 of a multilayer metal film, and an n-type GaN substrate 12 On the back surface, a striped n-side electrode 30 of a multilayer metal film formed by sequentially depositing Ti (titanium), Pt (platinum), and Au (gold) is provided.
[0032]
By the way, in this embodiment, as shown in FIG. 1, a through hole 32 having a diameter of 50 μm is provided in one row of the core portion 12a of the high-density defect region of the n-type GaN substrate 12. The core portion 12a is a portion having a particularly high crystal defect density among the high-density defect regions, and a region between the core portion 12a and the adjacent core portion 12a is a low-density defect region.
The n-side electrode 30 is provided so as to be positioned between the core portion 12 a that does not have a through hole and the through-hole 32, and the p-side electrode 28 is provided just above the n-side electrode 30. It is.
[0033]
The third electrode 34 is provided in the through hole 32.
In the present embodiment, as in the past, a drive current is applied between the p-side electrode 28 and the n-side electrode 30, and a frequency of several hundred MHz to several GHz is provided between the p-side electrode 28 and the third electrode 34. Apply a high frequency current. By superimposing the high-frequency current on the drive current, mode hopping noise can be reduced.
[0034]
Embodiment of Method for Manufacturing Nitride-Based Compound Semiconductor Device This embodiment is a method for manufacturing a nitride-based compound semiconductor device according to the first invention method. FIG. 2A to FIG. 2C are cross-sectional views or perspective views for each step in manufacturing a semiconductor laser device by the method of this embodiment. .
First, as shown in FIG. 2 (a), it penetrates through one row of the core portion 12a of the high-density defect region of the n-type GaN substrate 12 periodically having a high-density defect region whose crystal defect density is higher than the surrounding region. A hole 32 is provided. The core portion 12a is a portion having a particularly high crystal defect density even in the high-density defect region, and a region between the core portion 12a and the core portion 12a is a low-density defect region having a low crystal defect density.
When opening the through-hole 32, the through-hole 32 having a diameter of 50 μm that penetrates the core portion 12a is easily formed by wet etching using KOH or phosphoric acid as an etchant by using the crystal defect density. Can do. In this embodiment, the diameter of the through hole 32 is smaller than the diameter of the core portion 12a.
[0035]
The etching method for opening the through holes 32 is not limited to the wet etching method using KOH or phosphoric acid as an etchant, and a dry etching method or a thermal etching method can be applied.
[0036]
Next, on the n-type GaN substrate 12, as shown in FIG. 2B, for example, by MOCVD (Metalorganic Chemical Vapor Deposition), for example, at a growth temperature of 1000 ° C., sequentially, Si-doped. The n-type GaN layer 14 is grown to a thickness of 3.0 μm, the Si-doped n-type AlGaN cladding layer 16 is grown to a thickness of 0.5 μm, and the Si-doped n-type GaN optical waveguide layer 18 is grown to a thickness of 0.1 μm.
Subsequently, the active layer 20 having a multiple quantum well structure made of, for example, Ga _1-x In _x N (well layer) and Ga _1-y In _y N (barrier layer) is grown to a thickness of 40 nm at a growth temperature of 800 ° C. .
Further, at a growth temperature of 1000 ° C., the Mg-doped p-type GaN optical waveguide layer 22 is sequentially formed to a thickness of 0.1 μm, the Mg-doped p-type AlGaN cladding layer 24 is formed to a thickness of 0.5 μm, and the Mg-doped p-type GaN contact layer 26 is formed. Grow 0.5 μm thick.
[0037]
The growth process of the above-mentioned GaN-based compound semiconductor layer, for example, aluminum as a raw material gas (Al), trimethyl aluminum ((CH _{3) 3} Al), as a source gas of gallium (Ga), trimethyl gallium ((CH _{3) 3} Ga) or triethyl gallium _{((C 2 H 5) 3} Ga), ( as a raw material gas of in), trimethyl indium ((CH ₃₎ indium ₃ an in) can be used, respectively.
Further, ammonia gas (NH ₃ ) as a source gas of nitrogen, monosilane gas (SiH ₄ ) as a source gas of silicon, and methylbis = cyclopentadienylmagnesium (MeCP ₂ Mg) or bis as a source gas of magnesium = Cyclopentadienylmagnesium (CP ₂ Mg) can be used respectively.
[0038]
Next, as shown in FIG. 2C, for example, palladium, platinum, and gold are sequentially deposited on the p-type contact layer 26 to form a striped p-side electrode 28. Next, the back surface of the n-type GaN substrate 12 is polished and thinned, and then, for example, titanium, platinum, and gold are sequentially deposited on the back surface of the substrate to form a striped n-side electrode 30. Further, a third electrode 34 is provided in the through hole 32.
The nitride semiconductor laser device 10 shown in FIG. 1 can be completed by cleaving to a predetermined size and forming an end face reflecting film (not shown) on the end face of the resonator.
[0039]
Embodiment 2
The nitride-based compound semiconductor device according to this embodiment is an embodiment in which the nitride-based compound semiconductor device according to the present invention including the third electrode is applied to a nitride-based semiconductor laser device, and FIG. It is sectional drawing which shows the structure of the nitride type semiconductor laser element of the example of this embodiment.
As shown in FIG. 3, the nitride-based semiconductor laser device 40 of the present embodiment is provided with a third electrode 44 in contact with the emission end face 42, that is, the third electrode 44 in chip formation. Has the same configuration as that of the nitride-based semiconductor laser device 10 of the first embodiment except that it is cleaved so as to be in contact with the emission end face 42.
[0040]
In this embodiment, a driving current is supplied from the p-side electrode 28 to the n-side electrode 30, and a small current whose current value is smaller than the driving current is supplied from the p-side electrode 28 to the third electrode 44. 30 and the third electrode 44 are made to function as a tandem electrode, and the optical bistability of the light emitting element is enhanced.
In the laminated structure sandwiched between the p-side electrode 28 and the n-side electrode 30, light is amplified by supplying a current from the p-side electrode 28 to the n-side electrode 30. On the other hand, in the region near the emission end face 42, light is absorbed by the small current supplied from the p-side electrode 28 to the third electrode 44, and becomes a saturable absorber.
When the current supplied to the third electrode 44 is constant and the drive current is supplied from the p-side electrode 28 to the n-side electrode 30 as before, light absorption in the vicinity of the emission end face 42 is large before oscillation, but after oscillation, Since the light absorption in the region near the emission end face 42 is saturated, the threshold current is reduced and hysteresis occurs. Thereby, the optical bistability of a light emitting element can be improved.
[0041]
As long as it is within the technical scope of the present invention, the compound semiconductor layer can be epitaxially grown by MBE (Molecular Beam Epitaxy) method or the like without depending on the MOCVD method.
Moreover, although the through-hole 32 was mentioned as an example as a hole which opens the core part 12a, it does not necessarily need to be a through-hole and the blind hole drilled to the middle of the board | substrate may be sufficient.
[0042]
In the above-described embodiment, the GaN substrate 76 in which high-density defect regions are arranged in a square lattice shape is used as the GaN substrate. However, the present invention is not limited to this, and for example, as shown in FIG. A GaN substrate 82 in which density defect regions are arranged in a rectangular lattice shape, and a GaN substrate 84 in which high density defect regions are arranged in a hexagonal lattice shape as shown in FIG. 7C can be used.
Furthermore, as shown in FIGS. 8A and 8B, GaN substrates 86 and 88 in which high-density defect regions are linearly arranged can be used. 7 and 8 show the positional relationship between the high-density defect region and the laser stripe. 7 and 8, reference numeral 80 denotes a laser stripe.
[0043]
【The invention's effect】
According to the present invention, the third electrode is provided in the hole provided so as to penetrate or not penetrate the substrate in the core region having the highest defect density in the high-density defect region of the substrate, By supplying a current between the three electrodes, device characteristics such as wavelength, noise, and optical bistability are controlled.
As a result, a nitride-based compound semiconductor device that has a compact structure and has an unprecedented function of controlling device characteristics and can be manufactured by a simple process is realized.
[Brief description of the drawings]
1 is a cross-sectional view showing a configuration of a GaN-based semiconductor laser device according to Embodiment 1;
FIGS. 2A to 2C are cross-sectional views or perspective views for each step in manufacturing the GaN-based semiconductor laser device of Embodiment 1. FIG.
3 is a cross-sectional view showing a configuration of a GaN-based semiconductor laser device according to Embodiment 2. FIG.
FIGS. 4A and 4B are a plan view and a cross-sectional view of a GaN substrate for explaining a high-density defect region, respectively.
FIGS. 5A and 5B are diagrams showing an array of a rectangular lattice and an array of a hexagonal lattice, respectively.
6 (a) and 6 (b) respectively show an arrangement in which dot-like high-density defect regions are arranged in a line in an intermittent manner, and a high-density defect region is arranged in a line in a continuous manner. FIG.
FIGS. 7 (a) to 7 (c) show sections of GaN-based semiconductor laser elements on GaN substrates in which high-density defect regions are arranged in a square lattice, a rectangular lattice, and a hexagonal lattice, respectively. FIG.
FIGS. 8A and 8B are diagrams showing sections of a GaN-based semiconductor laser device on a GaN substrate in which high-density defect regions are linearly arranged, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... GaN-type semiconductor laser element of Example 1, 12 ... n-type GaN substrate, 12a ... Core part, 14 ... Si-doped n-type GaN layer, 16 ... Si-doped n-type AlGaN cladding layer, 18 ...... Si-doped n-type GaN optical waveguide layer, 20... Active layer having a multiple quantum well structure composed of Ga _1-x In _x N (well layer) and Ga _1-y In _y N (barrier layer), 22. ... Mg-doped p-type GaN optical waveguide layer, 24 ... Mg-doped p-type AlGaN cladding layer, 26 ... Mg-doped p-type GaN contact layer, 28 ... p-side electrode, 30 ... n-side electrode, 32 ... penetrating Hole 34... Third electrode 40... GaN-based semiconductor laser device of Example 2 42... Emitting end face 44... Third electrode 76... GaN substrate 78. Region, 80 ... Laser stripe, 82 ... ... GaN substrate in which high-density defect areas are arranged in a rectangular lattice, 84 ... GaN substrate in which high-density defect areas are arranged in a hexagonal lattice, 86, 88 ... High-density defect areas are arranged in a line GaN substrate.

Claims (7)

A semiconductor crystal substrate, a nitride-based compound semiconductor light-emitting device comprising a nitride compound semiconductor multilayer structure,
The semiconductor crystal substrate comprises a low density defect region and a high density defect region periodically arranged in the semiconductor crystal substrate surface in the low density defect region,
The high-density defect region penetrates the semiconductor crystal substrate;
A first electrode is provided at a predetermined position on the laminated structure;
A second electrode is provided on the back surface of the semiconductor crystal substrate;
A third electrode embedded in a hole provided so as to penetrate or not penetrate the core region having the highest defect density in the high-density defect region;
By applying a drive current between the first electrode and the second electrode and supplying a current between the first electrode and the third electrode, wavelength, noise or optical bistable A nitride-based compound semiconductor light-emitting device characterized by controlling the properties . The driving current is applied between the front Symbol the first electrode and the second electrode, and a high-frequency current is applied between the third electrode and the first electrode, a high frequency current on the drive current The nitride-based compound semiconductor light-emitting element according to claim 1, wherein noise is reduced by superimposing the elements. The nitride-based compound semiconductor light-emitting element is an edge-emitting type light-emitting element, the third electrode is provided in contact with the emission end face, and a driving current is applied between the first electrode and the second electrode. A small current having a current value smaller than a drive current is supplied between the first electrode and the third electrode so that the second electrode and the third electrode function as a tandem electrode. 2. The nitride-based compound semiconductor light-emitting device according to claim 1, wherein the optical bistability is enhanced. 4. The nitride-based compound semiconductor light-emitting element according to claim 1, wherein the high-density defect regions are periodically scattered on a substrate surface of the semiconductor crystal substrate. 5. 5. The high-density defect region is scattered in any arrangement of a square lattice shape, a rectangular lattice shape, and a hexagonal lattice shape on a substrate surface of the semiconductor crystal substrate. Nitride compound semiconductor light emitting device . 4. The high-density defect region is a linear high-density defect region that is periodically and spaced apart from each other on the substrate surface of the semiconductor crystal substrate. The nitride compound semiconductor light-emitting device according to any one of the above. The linear high-density defect region is a linear high-density defect region in which dot-like high-density defect regions are in contact with each other or intermittently arranged in a line, or a high-density defect region is continuously linear. The nitride-based compound semiconductor light-emitting device according to claim 6, wherein the nitride-based compound semiconductor light-emitting device is a high-density defect region extending in the region.

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