JP3696182B2 - Semiconductor laser element - Google Patents

Semiconductor laser element Download PDF

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Publication number
JP3696182B2
JP3696182B2 JP2002161782A JP2002161782A JP3696182B2 JP 3696182 B2 JP3696182 B2 JP 3696182B2 JP 2002161782 A JP2002161782 A JP 2002161782A JP 2002161782 A JP2002161782 A JP 2002161782A JP 3696182 B2 JP3696182 B2 JP 3696182B2
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direction
substrate
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JP2003060318A (en
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雄三郎 伴
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松下電器産業株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used for forming a GaN-based semiconductor device such as a GaN-based blue-violet semiconductor laser device, a GaN-based light-emitting diode device capable of emitting light from the ultraviolet to the red region, or a GaN-based high-frequency electronic device, and the semiconductor device. The present invention relates to a GaN-based compound semiconductor epitaxial growth wafer.
[0002]
[Prior art]
A nitride semiconductor containing nitrogen (N) as a group V element is considered promising as a material for a short-wavelength light-emitting element because of its relatively large band gap. Above all, the general formula Al x Ga y In z A gallium nitride (GaN) -based compound semiconductor represented by N (where 0 ≦ x, y, z ≦ 1, x + y + z = 1) has been actively studied, and a blue light-emitting diode (LED) device Green light-emitting diode elements have already been put into practical use.
[0003]
Further, as a light source for next-generation high-density optical discs such as HD-DVD (High Definition Digital Versatile Disk), a blue-violet semiconductor laser element having an oscillation wavelength of around 400 nm is eagerly desired, and a semiconductor laser using a gallium nitride based semiconductor material Research and development of devices are also actively conducted.
[0004]
FIG. 5 is a partially enlarged perspective view of an epitaxial growth wafer (hereinafter abbreviated as an epi wafer) used in a conventional gallium nitride compound semiconductor device.
[0005]
As shown in FIG. 5, the plane orientation of the main surface of the substrate 101 made of gallium nitride (GaN) has an off angle of 0.2 ° from the (0001) plane in the <1-100> direction of the zone axis. ing. On the main surface of the substrate 101, an element layer 102 made of an epitaxially grown gallium nitride semiconductor is formed.
[0006]
The surface form (surface morphology) of the element layer 102 is affected by a step (not shown) on the surface of the substrate 101 and has a plurality of steps appearing in the same direction (= <1-100> direction). . That is, a plurality of steps are formed in a direction having an off angle with respect to the surface orientation of the main surface of the substrate 101. In the specification of the present application, the minus sign “−” attached to the index of the plane orientation or the zone axis represents the inversion of one index following the minus sign for convenience.
[0007]
When a semiconductor laser device is manufactured using such an epi-wafer, the laser resonance direction and the step direction (= <1-100> direction) in the resonator constituting the waveguide are formed so as to be substantially perpendicular. ing. Here, if the resonance direction (stripe direction) of the resonator is aligned with the step direction (off-angle direction) of the substrate 101, the heights of the end faces facing each other in the resonator are shifted due to the respective steps. Loss (waveguide loss) increases. For this reason, the threshold current of the laser element increases, and as a result, the reliability also decreases.
[0008]
By the way, Japanese Patent Application Laid-Open No. 2000-156348 discloses a GaN compound in which an element layer having a step of several hundred to several thousand μm in width of a flat portion (terrace portion) sandwiched between adjacent steps is formed. A semiconductor epi-wafer is described.
[0009]
In the above publication, the resonance direction is set in a direction parallel to the step direction so that it can be cleaved on the (1-100) M plane of GaN. For this reason, it is necessary to make the width of the terrace portion larger than the length dimension of one side of the chip that can be cut at least as a chip.
[0010]
[Problems to be solved by the invention]
However, the GaN-based compound semiconductor epiwafer according to the above publication needs to have an extremely small off-angle of about 0.3 ° to 0.5 ° so that a terrace portion capable of obtaining a laser chip is formed. .
[0011]
Therefore, for example, since the off angle cannot be made larger than 1 °, the surface morphology of the epi-wafer is deteriorated, or the half width of the X-ray rocking curve that is an index of crystal orientation is increased. There is a problem that an element layer having high quality crystallinity cannot be obtained. For this reason, the characteristics of a semiconductor device manufactured using the conventional GaN-based compound semiconductor epiwafer are also insufficient.
[0012]
An object of the present invention is to solve the above-described conventional problems and to obtain high-quality crystallinity in an epitaxial layer (element layer) in a GaN-based compound semiconductor epiwafer having an off angle.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a GaN-based compound semiconductor epi-wafer according to the present invention is formed by growing a first nitride semiconductor belonging to a hexagonal system and a main surface of the substrate to form a semiconductor element. A device layer made of a second nitride semiconductor belonging to a hexagonal system, the plane orientation of the main surface of the substrate has an off angle in one direction from the (0001) plane, It has a striped surface configuration extending substantially parallel to the direction.
[0014]
According to the GaN-based compound semiconductor epi-wafer of the present invention, since the element layer has a striped surface form extending substantially parallel to one direction having an off-angle, the off-angle of the substrate is 1 ° or more. However, the width between the stripes (the width of the terrace portion) never narrows. For this reason, the surface form (surface morphology) of an element layer becomes favorable, and the element layer excellent in crystallinity can be obtained. The striped surface form is a step formed by one or two atomic layers appearing on the surface of the element layer.
[0015]
In the GaN-based compound semiconductor epi-wafer of the present invention, it is preferable that one direction is the <1-100> direction of the zone axis.
[0016]
In the GaN-based compound semiconductor epi-wafer of the present invention, the off angle is preferably 1 ° or more and 10 ° or less.
[0017]
A semiconductor device according to the present invention includes a substrate made of a first nitride semiconductor belonging to a hexagonal system, and a second material belonging to the hexagonal system that is formed on the main surface of the substrate by growth and belongs to the hexagonal system for forming the semiconductor device. Targeting a semiconductor element using a GaN-based compound semiconductor epi-wafer having an element layer made of a nitride semiconductor, the plane orientation of the main surface of the substrate has an off angle in one direction from the (0001) plane, and the element layer is It has a striped surface form extending substantially parallel to one direction.
[0018]
According to the semiconductor element of the present invention, since the element layer has a striped surface form extending substantially parallel to one direction having an off angle, the off angle of the substrate is increased to 1 ° or more. However, since the width between the stripes does not become narrow, the surface morphology of the element layer is good, and an element layer having excellent crystallinity can be obtained.
[0019]
In the semiconductor device of the present invention, it is preferable that one direction is a <1-100> direction of the crystal zone axis.
[0020]
In the semiconductor element of the present invention, the off angle is preferably 1 ° or more and 10 ° or less.
[0021]
The semiconductor element of the present invention is preferably a laser element.
[0022]
In this case, it is preferable that the laser element has a resonator formed substantially parallel to one direction.
[0023]
In this case, the off-angle is preferably 1 ° or more and 10 ° or less, and the end face of the resonator is preferably formed by cleavage.
[0024]
The semiconductor element of the present invention is preferably a light emitting diode element.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings.
[0026]
FIG. 1 is a partially enlarged perspective view of a GaN-based compound semiconductor epiwafer according to the first embodiment of the present invention.
As shown in FIG. 1, the epitaxial wafer 10 according to the first embodiment has a crystal system belonging to the hexagonal system, and its main surface is about 5 ° from the (0001) plane in the <1-100> direction of the zone axis. A substrate 11 made of gallium nitride (GaN) having an off-angle inclined by an angle, and a semiconductor element epitaxially grown on the main surface of the substrate 11 by a metalorganic thermal vapor phase epitaxy (MOVPE) method or the like And an element layer 12 made of a GaN-based compound semiconductor belonging to a hexagonal system.
[0027]
The surface morphology of the element layer 12 is a stripe extending substantially parallel to the <1-100> direction of the crystal zone axis, and the interval between the stripes is about 10 μm to 20 μm.
[0028]
The substrate 11 is not limited to liquid phase, vapor phase, or solid layer growth. Here, for example, a high temperature high pressure method, a MOVPE method, or a hydride vapor phase epitaxy (HVPE) method is used. Etc. are formed.
[0029]
When the X-ray rocking curve of the epi-wafer 10 having the element layer 12 was measured, it was confirmed that the half width was about 100 seconds or less. As described above, the conventional epi-wafer has a main surface with an off-angle smaller than 1 °, and the half width of the X-ray rocking curve in this case is about 200 seconds to 300 seconds. Therefore, it can be seen that the epi-wafer 10 according to the first embodiment has greatly improved crystallinity as compared with the conventional epi-wafer having an off-angle smaller than 1 °.
[0030]
Thus, by setting the off angle of the substrate 11 made of gallium nitride to about several degrees, for example, in the range of 1 ° to 10 °, the surface morphology of the element layer 12 epitaxially grown on the substrate 11 is As a result, it has been confirmed that the stripes extend substantially parallel to the <1-100> direction in the off-angle direction, and as a result, the crystallinity of the element layer 12 is remarkably improved.
[0031]
In the first embodiment, the MOVPE method is used as an epitaxial growth method for forming the element layer 12, but the present invention is not limited to this, and other epitaxial growth methods such as a molecular beam epitaxy (MBE) method or an HVPE method are used. It goes without saying that the present invention can be realized even if the method is used.
[0032]
(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
[0033]
FIG. 2 shows a partial cross-sectional configuration of a GaN-based compound semiconductor epi-wafer according to the second embodiment of the present invention.
[0034]
In FIG. 2, an element layer 12 made of a GaN-based compound semiconductor according to the second embodiment is an epitaxial layer having a semiconductor laser structure capable of emitting violet light.
[0035]
As shown in FIG. 2, the GaN-based compound semiconductor epi-wafer 10 is made of gallium nitride (GaN) whose main surface is inclined from the (0001) plane by about 2 ° in the <1-100> direction of the zone axis. An n-type semiconductor layer 21 made of n-type GaN, an n-type cladding layer 22 made of n-type aluminum gallium nitride (AlGaN), and an n-type light guide layer 23 made of n-type GaN are formed on the main surface of the substrate 11. A multiple quantum well (MQW) active layer 24 in which a plurality of well layers made of indium nitride (InGaN) and a barrier layer made of GaN are stacked, a p-type cap layer 25 made of p-type AlGaN, and p-type GaN. A p-type light guide layer 26, a p-type cladding layer 27 made of p-type AlGaN, and a p-type contact layer 28 made of p-type GaN are sequentially stacked by epitaxial growth. And it has a structure.
[0036]
The n-type cladding layer 22 and the p-type cladding layer 27 confine the carriers injected into the MQW active layer 24 and the recombination light by the carriers, and the n-type light guide layer 23 and the p-type light guide layer 26 are carriers and Improve the confinement efficiency of recombination light. The p-type cap layer 25 functions as a barrier layer that prevents electrons injected from the n-type semiconductor layer 21 from leaking into the p-type light guide layer 26 without being injected into the MQW active layer 24.
[0037]
The resonance direction (longitudinal direction) of the resonator is the direction perpendicular to the M plane, that is, the crystal axis of the crystal so that the cleaved end face of the resonator provided in the semiconductor laser structure is the M plane of the gallium nitride crystal plane. The <1-100> direction is assumed.
[0038]
Here, since the off angle direction of the substrate 11 is also the <1-100> direction, the surface morphology of the element layer 12 formed by epitaxial growth on the substrate 11 is, as described above, the off angle direction (<1-100>). Therefore, the longitudinal direction of the resonator, the so-called stripe direction, and the direction in which the stripe pattern extends coincide with each other. Accordingly, the width between adjacent stripes (terrace portion) is 10 μm to 20 μm, and the resonator width is usually about 2 μm to 3 μm. Therefore, the resonator can be reliably formed on the terrace portion. .
[0039]
In the second embodiment, the off angle on the main surface of the substrate 11 is about 2 °, but it may be 1 ° or more and 10 ° or less.
[0040]
In the MQW active layer 24, the well layer is InGaN and the barrier layer GaN. Alternatively, the well layer may be GaN and the barrier layer may be AlGaN.
[0041]
Further, the n-type clad layer 22 and the p-type clad layer 27 may be superlattice clad layers made of a laminate of an AlGaN layer and a GaN layer, instead of an AlGaN single layer structure. Here, when the superlattice cladding layer is used, impurity doping such as silicon (Si) as an n-type dopant or magnesium (Mg) as a p-type dopant is applied to at least one of the AlGaN layer and the GaN layer. Just do it.
[0042]
(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
[0043]
FIG. 3 shows a partial cross-sectional structure of a GaN-based compound semiconductor epiwafer according to the third embodiment of the present invention.
[0044]
In FIG. 3, an element layer 12 made of a GaN-based compound semiconductor according to the third embodiment is an epitaxial layer having a light emitting diode structure capable of emitting blue light.
[0045]
As shown in FIG. 3, the GaN-based compound semiconductor epiwafer 10 is made of gallium nitride (GaN) having an off-angle whose main surface is inclined by about 2 ° in the <1-100> direction of the crystal zone axis from the (0001) plane. An n-type semiconductor layer 41 made of n-type GaN, an n-type superlattice clad layer 42 made of a laminate of an n-type InGaN layer and an n-type GaN layer, a well layer made of InGaN, A multiple quantum well (MQW) active layer 43 in which a plurality of GaN barrier layers are laminated, a p-type cap layer 44 made of p-type AlGaN, and a p-type made of a laminate of a p-type AlGaN layer and a p-type GaN layer. A type superlattice cladding layer 45 and a p-type contact layer 46 made of p-type GaN are sequentially stacked by epitaxial growth.
[0046]
Also in the third embodiment, the surface morphology of the element layer 12 is a striped pattern extending in a direction substantially parallel to the off-angle direction (<1-100> direction), and the half width of the X-ray rocking curve is about 80. As the time becomes smaller, the crystallinity is remarkably improved as compared with the conventional case. As a result, it has been confirmed that the light emission efficiency of the GaN-based blue light-emitting diode element manufactured using the epi-wafer according to the third embodiment is greatly increased.
[0047]
In the third embodiment, the off angle on the main surface of the substrate 11 is about 2 °, but it may be 1 ° or more and 10 ° or less.
[0048]
Further, in the MQW active layer 43, the well layer may be GaN and the barrier layer may be AlGaN instead of the well layer being InGaN and the barrier layer GaN.
[0049]
In addition, the n-type cladding layer 42 has a superlattice structure composed of a stacked body of an n-type InGaN layer and an n-type GaN layer, but instead, a superlattice structure of an n-type AlGaN layer and an n-type GaN layer. Or a single layer structure made of n-type GaN or n-type AlGaN.
[0050]
In addition, the p-type cladding layer 45 has a superlattice structure composed of a stacked body of a p-type AlGaN layer and a p-type GaN layer. Alternatively, a single-layer structure composed of p-type GaN or p-type AlGaN may be used. Good.
[0051]
Also here, as in the second embodiment, when each cladding layer has a superlattice structure, the impurity doping of the n-type dopant or the p-type dopant is the well layer and the barrier layer in the superlattice structure. This can be done for one of the least.
[0052]
【Example】
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[0053]
FIG. 4 shows a first example of the present invention, and is a perspective view of a violet semiconductor laser device fabricated using a GaN-based compound semiconductor epiwafer according to the second embodiment.
[0054]
In the first embodiment, a MOVPE method in which the growth pressure is 300 Torr (1 Torr = 133.322 Pa), which is a reduced pressure state, is used as the crystal growth method for the element layer.
[0055]
Group III sources include trimethylaluminum (TMAl: (CH Three ) Three Al), trimethylgallium (TMGa: (CH Three ) Three Ga) or trimethylindium (TMIn: (CH Three ) Three A source gas composed of In) is used. In addition, group V sources include ammonia (NH Three ) Use gas. Examples of n-type impurity materials include monosilane (SiH Four For example, cyclopentadienyl magnesium (Cp) 2 Mg: (C Five H Five ) 2 Mg) is used. The carrier gas for these source gases includes hydrogen (H 2 ) Gas and nitrogen (N 2 ) Use gas.
[0056]
Further, as the substrate of the element layer, a substrate 11 made of gallium nitride (GaN) having a main surface inclined by about 2 ° in the <1-100> direction from the (0001) plane is used.
[0057]
First, an example of the growth process of the element layer 12 shown in FIG. 2 will be described.
[0058]
After the substrate 11 is put into the reaction chamber of the MOVPE apparatus, the substrate 11 is heated to about 1050 ° C., which is the growth temperature of the element layer 12. Here, when the temperature of the substrate reaches about 400 ° C., NH is prevented so that the surface of the substrate 11 is not transformed by heat. Three Start supplying gas. After the substrate temperature reaches about 1050 ° C. and a few minutes have passed, TMGa and SiH Four Supply of gas is started, and an n-type semiconductor layer 21 made of n-type GaN having a thickness of about 3 μm is grown on the main surface of the substrate 11. Subsequently, supply of TMAl is started, and an n-type cladding layer 22 made of n-type AlGaN having a thickness of about 0.7 μm is grown on the n-type semiconductor layer 21. Subsequently, the supply of TMAl is stopped, and an n-type light guide layer 23 made of n-type GaN having a thickness of about 10 nm is grown.
[0059]
Thereafter, the growth temperature is lowered to about 800 ° C., and then an MQW active layer 24 is grown on the n-type light guide layer 23. Specifically, TMGa, TMIn and NH Three , A well layer made of InGaN having a thickness of about 3 nm is grown, and TMGa and NH Three , A barrier layer made of GaN having a thickness of about 7.5 nm is grown, and these well layers and barrier layers are alternately stacked to obtain three pairs of MQW active layers 24.
[0060]
Subsequently, after raising the growth temperature to 1000 ° C., TMAl, TMGa, NH Three And Cp 2 By supplying Mg, a p-type cap layer 25 made of p-type AlGaN having a thickness of about 2 nm is grown on the MQW active layer 24. Thereafter, the supply of TMAl is stopped, and a p-type light guide layer 26 made of p-type GaN having a thickness of about 10 nm is grown on the p-type cap layer 25. Thereafter, the supply of TMAl is restarted, and a p-type cladding layer 27 made of p-type AlGaN having a thickness of about 0.5 μm is grown on the p-type light guide layer 26. Subsequently, the supply of TMAl is stopped, and a p-type contact layer 28 made of p-type GaN having a thickness of about 0.2 μm is grown on the p-type cladding layer 27.
[0061]
Subsequently, after the p-type contact layer 28 is grown, the source gases TMGa, CP 2 Mg and NH Three The supply of N 2 And H 2 While the carrier gas consisting of is supplied as it is, it is cooled to room temperature, and then the epi-wafer 10 is taken out from the reaction chamber.
[0062]
The surface morphology of the epitaxial wafer 10 according to the first example formed in this way is, as shown in FIG. 1, the direction of the off angle of the main surface of the substrate 11, that is, <1-100> of the crystallographic axis. A striped pattern extending in a direction substantially parallel to the direction is shown.
[0063]
The half width of the X-ray rocking curve obtained from the epi-wafer 10 is about 80 seconds.
[0064]
Next, an example of a method for manufacturing the violet semiconductor laser device shown in FIG. 4 will be described with reference to the drawings.
[0065]
First, silicon oxide (SiO 2) is deposited on the entire surface of the p-type contact layer 28 by sputtering or CVD. 2 After the mask forming film (not shown) is deposited, the mask forming film is patterned into a ridge stripe shape by lithography to form a dry etching mask film from the mask forming film. Subsequently, the p-type contact layer 28 and the p-type cladding layer 27 are etched by a reactive ion etching method to the extent that the p-type light guide layer 26 is exposed using the formed mask film, and the p-type contact layer 28 and The ridge stripe shape of the mask film is transferred to the p-type cladding layer 27.
[0066]
Next, after removing the mask film, a protective insulating film 29 made of silicon oxide is formed on the upper and side surfaces of the etched p-type contact layer 28 and p-type cladding layer 27 and the exposed p-type light guide layer 26. Then, an opening for exposing the p-type contact layer 28 is selectively formed in the protective insulating film 29 by lithography and dry etching.
[0067]
Next, a resist pattern having an opening in the exposed region of the p-type contact layer 28 is formed by lithography. Subsequently, after sequentially depositing nickel (Ni) and gold (Au) by an evaporation method or the like, a p-side electrode 30 made of a laminate of Ni and Au and in ohmic contact with the p-type contact layer 28 is formed by a lift-off method. Form.
[0068]
Next, the surface of the substrate 11 opposite to the element layer 12 (back surface) is polished until its thickness becomes about 100 μm. Thereafter, titanium (Ti) and aluminum (Al) are sequentially deposited on the back surface by a vapor deposition method or the like to form an n-side electrode 31 made of a laminate of Ti and Al and in ohmic contact with the substrate 11.
[0069]
Next, the epi-wafer 10 is cleaved at the M plane to form a bar-shaped semiconductor laminate including a plurality of resonators and exposing the end faces of the resonators. After that, the reflective end face (rear face) of the cleavage plane is coated with a highly reflective film made of a dielectric film having a reflectivity of about 80%, and the opposite end face (front face) has a reflectivity of about A low-reflection film made of 20% dielectric film is coated. Thereafter, the bar-shaped semiconductor laminate is divided into chips so as to include at least one resonator.
[0070]
The GaN-based violet semiconductor laser device fabricated in this way has an oscillation wavelength of 405 nm. When the output characteristics and current characteristics of the laser beam are evaluated, the threshold current is about 45 mA and the threshold voltage is about Good characteristics of 4.5V are obtained. As a result, since the operating current and operating voltage when the optical output is 30 mW can be reduced, the injected power is reduced, so that the reliability is improved and the life can be extended.
[0071]
The MQW active layer 24 is composed of a well layer composed of InGaN and a barrier layer composed of GaN. Instead, the MQW active layer 24 is composed of a well layer composed of GaN or AlGaN and a barrier layer composed of n-type AlGaN. Then, a laser beam having an oscillation wavelength in the ultraviolet region can be obtained.
[0072]
In the first embodiment, neither the well layer nor the active layer of the MQW active layer 24 is doped with an n-type impurity, but the n-type impurity is diffused by the diffusion from the n-type light guide layer 23 during growth. May show conductivity. However, at the time of growing the MQW active layer 24, at least one of the well layer and the active layer may be positively doped with impurities.
[0073]
(Second embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
[0074]
The second example shows an example of a method for manufacturing a blue light-emitting diode element manufactured using the GaN-based compound semiconductor epiwafer according to the second embodiment.
[0075]
Also here, the MOVPE method in which the growth pressure is 300 Torr which is a reduced pressure state is used as the crystal growth method of the element layer.
[0076]
As in the first embodiment, a source gas made of trimethylaluminum (TMAl), trimethylgallium (TMGa) or trimethylindium (TMIn) is used as the group III source. In addition, group V sources include ammonia (NH Three ) Use gas. Examples of n-type impurity materials include monosilane (SiH Four For example, cyclopentadienyl magnesium (Cp) 2 Mg) is used. Further, hydrogen gas and nitrogen gas are used as carrier gases for these source gases.
[0077]
As the substrate on which the element layer is grown, a substrate 11 made of gallium nitride (GaN) having a main surface inclined by about 5 ° in the <1-100> direction from the (0001) plane is used.
[0078]
First, after the substrate 11 is put into the reaction chamber of the MOVPE apparatus, the substrate 11 is heated to about 1050 ° C., which is the growth temperature of the element layer 12. Here, when the temperature of the substrate reaches about 400 ° C., NH is prevented so that the surface of the substrate 11 is not transformed by heat. Three Start supplying gas. After the substrate temperature reaches about 1050 ° C. and a few minutes have passed, TMGa and SiH Four Supply of gas is started, and an n-type semiconductor layer 41 made of n-type GaN having a thickness of about 3 μm is grown on the main surface of the substrate 11.
[0079]
Subsequently, an n-type superlattice cladding layer 42 made of n-type GaN / undoped InGaN is grown on the n-type semiconductor layer 41. Specifically, TMGa, NH Three And SiH Four To grow a barrier layer made of n-type GaN having a film thickness of about 2.5 nm, and TMGa, TMIn and NH Three , A well layer made of undoped InGaN having a thickness of about 2.5 nm is grown, and these barrier layers and well layers are alternately stacked.
[0080]
Thereafter, the growth temperature is lowered to about 800 ° C., and then an MQW active layer 43 is grown on the n-type superlattice cladding layer 42. Specifically, TMGa, TMIn and NH Three , A well layer made of InGaN having a thickness of about 3 nm is grown, and TMGa, NH Three And SiH Four , A barrier layer made of n-type GaN having a thickness of about 7.5 nm is grown, and these well layers and barrier layers are alternately stacked to obtain five pairs of MQW active layers 43.
[0081]
Subsequently, after raising the growth temperature to 1000 ° C., TMAl, TMGa, NH Three And Cp 2 By supplying Mg, a p-type cap layer 44 made of p-type AlGaN having a thickness of about 2 nm is grown on the MQW active layer 43.
[0082]
Subsequently, a p-type superlattice cladding layer 45 made of p-type AlGaN / undoped GaN is grown on the p-type cap layer 44. Specifically, TMGa, TMAl, NH Three And Cp 2 By supplying Mg, a barrier layer made of p-type AlGaN having a thickness of about 2.5 nm is grown, and TMGa and NH Three , A well layer made of GaN having a thickness of about 2.5 nm is grown, and these barrier layers and well layers are alternately stacked.
[0083]
Next, TMGa, NH Three And Cp 2 By supplying Mg, a p-type contact layer 46 made of p-type GaN having a thickness of about 0.2 μm is grown on the p-type superlattice cladding layer 45.
[0084]
Next, although not shown, a p-side electrode is formed on the p-type contact layer, an n-side electrode is formed on the surface of the substrate 11 opposite to the element layer 12, and then the substrate 11 is formed as desired. Divide into chips of size.
[0085]
The surface morphology of the epitaxial wafer 10 according to the second embodiment formed in this way is substantially parallel to the off-angle direction of the main surface of the substrate 11, that is, the <1-100> direction, as shown in FIG. A striped pattern extending in various directions is shown.
[0086]
Moreover, the half-value width of the X-ray rocking curve obtained from the epi-wafer 10 is about 80 seconds, and it can be seen that good crystallinity is exhibited.
[0087]
The n-type superlattice cladding layer 42 is doped with impurities only in the GaN layer that is the barrier layer, and the p-type superlattice cladding layer 45 is also doped with impurities only in the AlGaN layer that is the barrier layer. What is necessary is just to dope at least one among well layers.
[0088]
In addition, the MQW active layer 43 is doped with impurities only in the GaN layer which is a barrier layer, but it may be doped in at least one of the barrier layer and the well layer, and both the barrier layer and the well layer may be undoped. Good.
[0089]
As described above, the superlattice layers 42 and 45 and the MQW active layer 43 are not substantially doped with impurities during crystal growth. However, impurities may be included in the undoped layer due to diffusion of impurities from the semiconductor layer adjacent to these undoped layers and doped with impurities during or after crystal growth. Therefore, in this specification, an undoped layer is not limited to a semiconductor layer that is not substantially doped with impurities during crystal growth, but a semiconductor layer that has impurities contained in an adjacent semiconductor layer as a result of diffusion. Also say.
[0090]
【The invention's effect】
According to the GaN-based compound semiconductor epiwafer of the present invention and a semiconductor device fabricated using the epiwafer, the width of the stripes is not reduced even when the off-angle of the substrate is increased to 1 ° or more. The surface morphology of the film becomes good, and an element layer having excellent crystallinity can be obtained.
[Brief description of the drawings]
FIG. 1 is a partially enlarged perspective view showing a GaN-based compound semiconductor epiwafer according to a first embodiment of the present invention.
FIG. 2 is a partial cross-sectional view of a GaN-based compound semiconductor epiwafer according to a second embodiment of the present invention.
FIG. 3 is a partial cross-sectional view of a GaN-based compound semiconductor epiwafer according to a third embodiment of the present invention.
FIG. 4 is a perspective view showing a violet semiconductor laser device fabricated using a GaN-based compound semiconductor epiwafer according to the first embodiment of the present invention.
FIG. 5 is a partially enlarged perspective view showing a conventional GaN-based compound semiconductor epi-wafer.
[Explanation of symbols]
10 Epi wafer
11 Substrate
12 element layers
21 n-type semiconductor layer
22 n-type cladding layer
23 n-type light guide layer
24 Multiple quantum well (MQW) active layer
25 p-type cap layer
26 p-type light guide layer
27 p-type cladding layer
28 p-type contact layer
29 Protective insulating film
30 p-side electrode
31 n-side electrode
41 n-type semiconductor layer
42 n-type superlattice cladding layer
43 Multiple quantum well (MQW) active layer
44 p-type cap layer
45 p-type superlattice cladding layer
46 p-type contact layer

Claims (2)

  1. A substrate made of a first nitride semiconductor belonging to a hexagonal system;
    A semiconductor laser device using a GaN-based compound semiconductor epi-wafer having a device layer made of a second nitride semiconductor belonging to a hexagonal system and formed by growth on the main surface of the substrate. hand,
    The plane orientation of the principal surface of the substrate has an off angle of 1 ° or more and 10 ° or less in one direction from the (0001) plane,
    The element layer have a stripe-like surface morphology extending substantially parallel to said one direction,
    Semiconductors laser devices resonance direction (longitudinal direction) has a cavity which is substantially parallel to said one direction.
  2. The one direction, the semiconductor laser device according to claim 1 <1-100> Ru direction Der the zone axis.
JP2002161782A 2001-06-06 2002-06-03 Semiconductor laser element Active JP3696182B2 (en)

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US6596079B1 (en) 2000-03-13 2003-07-22 Advanced Technology Materials, Inc. III-V nitride substrate boule and method of making and using the same
JP4276020B2 (en) 2003-08-01 2009-06-10 住友電気工業株式会社 Method for producing group III nitride compound semiconductor
US7118813B2 (en) * 2003-11-14 2006-10-10 Cree, Inc. Vicinal gallium nitride substrate for high quality homoepitaxy
JP2010168277A (en) * 2004-03-17 2010-08-05 Sumitomo Electric Ind Ltd Semiconductor light emitting device
JP2005340765A (en) * 2004-04-30 2005-12-08 Sumitomo Electric Ind Ltd Semiconductor light emitting element
JP4691911B2 (en) * 2004-06-11 2011-06-01 日立電線株式会社 III-V nitride semiconductor free-standing substrate manufacturing method
US7339255B2 (en) 2004-08-24 2008-03-04 Kabushiki Kaisha Toshiba Semiconductor device having bidirectionally inclined toward <1-100> and <11-20> relative to {0001} crystal planes
JP3816942B2 (en) 2004-10-27 2006-08-30 三菱電機株式会社 Manufacturing method of semiconductor device
JP4997744B2 (en) * 2004-12-24 2012-08-08 日亜化学工業株式会社 Nitride semiconductor device and manufacturing method thereof
JP2006210660A (en) * 2005-01-28 2006-08-10 Hitachi Cable Ltd Manufacturing method of semiconductor substrate
JP2006210795A (en) * 2005-01-31 2006-08-10 Sanyo Electric Co Ltd Compound semiconductor light emitting device
JP2006310766A (en) * 2005-03-31 2006-11-09 Sanyo Electric Co Ltd Gallium nitride compound semiconductor laser element and manufacturing method therefor
DE102005021099A1 (en) * 2005-05-06 2006-12-07 Universität Ulm GaN layers
US7884447B2 (en) 2005-07-11 2011-02-08 Cree, Inc. Laser diode orientation on mis-cut substrates
EP2003696B1 (en) 2007-06-14 2012-02-29 Sumitomo Electric Industries, Ltd. GaN substrate, substrate with epitaxial layer, semiconductor device and method of manufacturing GaN substrate
JP2010536181A (en) * 2007-08-08 2010-11-25 ザ リージェンツ オブ ザ ユニバーシティ オブ カリフォルニアThe Regents of The University of California Planar nonpolar M-plane III-nitride thin films grown on miscut substrates
JP5262545B2 (en) * 2007-10-29 2013-08-14 日立電線株式会社 Nitride semiconductor free-standing substrate and device using the same
CN102598320B (en) * 2010-04-02 2016-01-13 松下知识产权经营株式会社 Nitride-based semiconductor device
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US9646827B1 (en) 2011-08-23 2017-05-09 Soraa, Inc. Method for smoothing surface of a substrate containing gallium and nitrogen

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