WO2019039208A1

WO2019039208A1 - Group 13 element nitride layer, freestanding substrate and functional element

Info

Publication number: WO2019039208A1
Application number: PCT/JP2018/028563
Authority: WO
Inventors: 崇行平尾; 中西　宏和; 幹也市村; 孝直下平; 坂井　正宏; 隆史吉野
Original assignee: 日本碍子株式会社
Priority date: 2017-08-24
Filing date: 2018-07-31
Publication date: 2019-02-28
Also published as: JPWO2019039208A1; JP6854902B2

Abstract

When the upper surface 13a of this group 13 element nitride crystal layer 13 is observed using cathode luminescence, there is a linear high luminance light-emitting portion 5 and a low luminance light-emitting region 6 adjoining the low luminance light-emitting portion 5. The half-width of (0002) plane reflection of the X-ray rocking curve on the upper surface 13a falls within the range of 20 seconds to 3000 seconds, and the arithmetic mean roughness Ra of the upper surface 13a falls within the range of 0.05 nm to 1.0 nm, inclusive.

Description

Group 13 element nitride layer, free-standing substrate and functional element

The present invention relates to a group 13 element nitride layer, a free-standing substrate and a functional device.

As a light emitting element such as a light emitting diode (LED) using a single crystal substrate, one in which various gallium nitride (GaN) layers are formed on sapphire (α-alumina single crystal) is known. For example, on a sapphire substrate, an n-type GaN layer, a multiple quantum well layer (MQW) in which quantum well layers composed of InGaN layers and barrier layers composed of GaN layers are alternately stacked, and p-type GaN layers are sequentially deposited. Those having a different structure are mass-produced.

The gallium nitride layer described in Patent Document 1 is polycrystalline gallium nitride composed of a large number of gallium nitride single crystal particles, and a large number of columnar gallium nitride single crystal particles are arranged in the lateral direction.

The gallium nitride layer described in Patent Document 2 is polycrystalline gallium nitride composed of a large number of gallium nitride single crystal particles, and a large number of columnar gallium nitride single crystal particles are arranged in the lateral direction. In addition, the average tilt angle (average value of the inclination of crystal orientation (crystal axis) in the direction normal to the surface) on the surface is 1 to 10 °.

In Patent Document 3, a large number of inclusions are included from the bottom to an intermediate position, and a plurality of grain boundaries including only a low concentration are formed diagonally from the lower surface from the intermediate position to the upper surface. In addition, the grain boundaries extend obliquely in the direction having an angle of 50 to 70 ° with respect to the c axis.

Patent Document 5 describes that a gallium nitride crystal having a low dislocation density is obtained by increasing the Ga ratio in the melt.

Patent No. 5770905 Patent No. 6154066 Patent No. 5897790 WO 2011/046203 WO 2010/084682

When light emitting devices are fabricated on gallium nitride crystals described in

Patent Documents

1 and 2, the current path may be interrupted to cause a decrease in light emission efficiency depending on the balance between the device size and the particle diameter. It turned out. Although the reason for this is not clear, anisotropy in orientation between single crystal grains may be involved.

In the gallium nitride crystals of Patent Documents 3 and 4, the larger the diameter, the more difficult it is to control the flow of the melt over the entire surface of the substrate, and in some cases voids may remain around the crystal.

In Patent Document 5, the grain size can be increased to reduce the dislocation density by controlling the flow of the high Ga ratio and the flux, but voids are likely to be contained between grains.

An object of the present invention is to reduce dislocation density in a Group 13 element nitride crystal layer comprising a Group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or mixed crystals thereof and having top and bottom surfaces. It is possible to provide a microstructure which is capable of reducing the variation of the characteristics throughout.

A first aspect of the present invention is a Group 13 element nitride crystal layer comprising a Group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or mixed crystals thereof, and having a top surface and a bottom surface. ,
When the upper surface is observed by cathode luminescence, it has a linear high luminance light emitting portion and a low luminance light emitting region adjacent to the high luminance light emitting portion,
The half value width of (0002) plane reflection of the X-ray rocking curve on the upper surface is 3000 seconds or less and 20 seconds or more,
Arithmetic mean roughness Ra of the upper surface is 0.05 nm or more and 1.0 nm or less.

The second aspect of the present invention is a Group 13 element nitride crystal layer comprising a Group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or mixed crystals thereof, and having a top surface and a bottom surface. There,
When the upper surface is observed by cathode luminescence, it has a high brightness light emitting portion and a low brightness light emitting region adjacent to the high brightness light emitting portion,
The half value width of (1000) plane reflection of the X-ray rocking curve on the upper surface is 10000 seconds or less and 20 seconds or more,
Arithmetic mean roughness Ra of the upper surface is 0.05 nm or more and 1.0 nm or less.

The present invention also relates to a self-supporting substrate characterized by comprising the group 13 element nitride layer.

Also, the present invention is
A composite substrate, comprising: a support substrate; and the group 13 element nitride layer provided on the support substrate.

Further, the present invention relates to a functional device having the above-mentioned self-supporting substrate and a functional layer provided on the above-mentioned Group 13 element nitride layer.

In addition, the present invention relates to a functional device including the composite substrate and a functional layer provided on the group 13 element nitride layer.

According to the first aspect of the present invention, when the top surface of the Group 13 element nitride crystal layer is observed by cathode luminescence, a linear high luminance light emitting portion and a low luminance light emitting region adjacent to the high luminance light emitting portion And the half width of (0002) plane reflection of the X-ray rocking curve on the upper surface is 3000 seconds or less and 20 seconds or more. This is because a linear high-intensity light emitting portion appears on the upper surface, so that a linear high-intensity light emitting portion in which a dopant component, a trace amount component, and the like contained in a Group 13 element nitride crystal are dark is generated. Means. At the same time, since the average tilt angle on the upper surface is small and the orientations of the crystal axes are substantially aligned, a very homogeneous microstructure similar to a single crystal is obtained.

According to the second aspect of the present invention, when the upper surface of the Group 13 element nitride crystal layer is observed by cathode luminescence, a linear high luminance light emitting portion and a low luminance light emitting region adjacent to the high luminance light emitting portion And the half value width of (1000) plane reflection of the X-ray rocking curve on the upper surface of the group 13 element nitride crystal layer is 10000 seconds or less and 20 seconds or more. This means that since the linear high-intensity light emitting portion appears on the upper surface, the dopant component contained in the Group 13 element nitride crystal forms a very linear high-intensity light emitting portion that is very dark. doing. At the same time, since the average twist angle on the upper surface is small and the orientations of the crystal axes are substantially aligned, a very homogeneous microstructure similar to a single crystal is obtained.

Group 13 element nitride crystal layers having such novel microstructures can reduce dislocation density even if the size is increased (for example, even if the diameter is 6 inches or more), and the variation in characteristics can be reduced overall It is possible to provide a group 13 element nitride crystal layer.
In addition to this, the arithmetic average roughness Ra of the upper surface of the group 13 element nitride crystal layer is 0.05 nm or more and 1.0 nm or less. This makes it possible to suppress the generation of surface pits when epitaxially growing a functional device layer such as an LD device or an LED device on the top surface of a Group 13 element nitride crystal layer.

(A) shows the state in which the alumina layer 2, the seed crystal layer 3 and the group 13 element nitride crystal layer 13 are provided on the support substrate 1, and (b) is a group 13 element nitride separated from the support substrate The crystal layer 13 is shown. FIG. 6 is a schematic view for explaining a cathode luminescence image of the upper surface 13 a of the group 13 element nitride crystal layer 13. It is a photograph which shows the cathode luminescence image of upper surface 13a of 13 group element nitride crystal layer 13. FIG. It is a partial enlarged photograph of FIG. It is a schematic diagram corresponding to the cathode luminescence image of FIG. It is a photograph which shows the cathode luminescence image of the section of 13 group element nitride crystal layer 13. 7 is a scanning electron micrograph showing a cross section of a Group 13 element nitride crystal layer 13; It is a schematic diagram which shows the functional element 21 which concerns on this invention. It is a photography picture with a scanning electron microscope of the upper surface of 13 group element nitride crystal layer. 2 shows a gray scale histogram generated from a CL image.

Hereinafter, the present invention will be described in more detail.
(Group 13 element nitride crystal layer)
The Group 13 element nitride crystal layer of the present invention is composed of Group 13 element nitride crystals selected from gallium nitride, aluminum nitride, indium nitride or mixed crystals thereof, and has top and bottom surfaces. For example, as shown in FIG. 1B, in the group 13 element nitride crystal layer 13, the top surface 13a and the bottom surface 13b face each other.

The nitride constituting the Group 13 element nitride crystal layer is gallium nitride, aluminum nitride, indium nitride or mixed crystals thereof. Specifically, GaN, AlN, InN, Ga _x Al _1-x N (1>x> 0), Ga _x In _1-x N (1>x> 0), Ga _x Al _y In _z N (1 >X> 0, 1>y> 0, x + y + z = 1).

Particularly preferably, the nitride constituting the Group 13 element nitride crystal layer is a gallium nitride based nitride. _{_{Specifically, GaN, Ga x Al 1-}} x N (1>x> 0.5), Ga x In 1-x N (1>x> 0.4), Ga x Al y In z N (1>x> 0.5 , 1>y> 0.3, x + y + z = 1).

Group 13 element nitrides may be doped with zinc, calcium or other n-type dopants or p-type dopants, in which case polycrystalline group 13 element nitrides may be p-type electrodes, n-type electrodes, p It can be used as a member or layer other than a substrate such as a mold layer and an n-type layer. Preferred examples of the p-type dopant include one or more selected from the group consisting of beryllium (Be), magnesium (Mg), strontium (Sr), and cadmium (Cd). Preferred examples of the n-type dopant include one or more selected from the group consisting of silicon (Si), germanium (Ge), tin (Sn) and oxygen (O).

Here, when the upper surface 13a of the group 13 element nitride crystal layer 13 is observed by cathode luminescence, it is adjacent to the linear high-intensity light emitting portion 5 and the high-intensity light emitting portion 5 as schematically shown in FIG. And a low luminance light emitting area 6.

However, observation by cathode luminescence (CL) shall be performed as follows.
For CL observation, a scanning electron microscope (SEM) with a cathode luminescence detector is used. For example, when using Hitachi High-Technologies S-3400N scanning electron microscope with Gatan MiniCL system, measurement conditions are: acceleration voltage 10 kV, probe current “90” with CL detector inserted between sample and objective lens The working distance (W.D.) is preferably 22.5 mm and observed at a magnification of 50 times.
Further, the high luminance light emitting portion and the low luminance light emitting region are distinguished as follows from the observation by cathode luminescence.
Image analysis software (for example, Mitani Shoji Co., Ltd. WinROOF Ver. 6.1), the luminance of the image observed CL at an acceleration voltage of 10 kV, probe current “90”, working distance (W.D.) 22.5 mm, magnification 50 × 3. Create a 256-step gray scale histogram using the vertical axis as the frequency and the horizontal axis as the luminance (GRAY) using 3). In the histogram, as shown in FIG. 10, two peaks are confirmed, and the high side is defined as a high brightness light emitting portion and the low side as a low brightness light emitting region with the brightness at which the frequency is minimum between the two peaks as a boundary. Do.

Further, on the top surface of the group 13 element nitride crystal layer, the low luminance light emitting region is adjacent to the linear high luminance light emitting portion. By this, adjacent low-intensity light emission areas are divided by the linear high-intensity light emission parts located between them. Here, that the high brightness light emitting portion is linear means that the high brightness light emitting portion is elongated and elongated between adjacent low brightness light emitting regions to form a boundary line.

Here, the line made by the high-intensity light emitting portion may be a straight line, a curved line, or a combination of a straight line and a curved line. The curve may include various forms such as arc, ellipse, parabola, hyperbola and the like. Moreover, although the high-intensity light emission part from which a direction mutually differs may be continuous, the terminal of the high-intensity light emission part may be cut off.

In the upper surface of the group 13 element nitride crystal layer, the low luminance light emitting region may be an exposed surface of the group 13 element nitride crystal grown therebelow, and is two-dimensionally spread in a planar manner. On the other hand, the high brightness light emitting portion is linear, but extends in a one-dimensional manner as a boundary that divides adjacent low brightness light emitting regions. This is because, for example, a dopant component and a trace component are discharged from a Group 13 element nitride crystal grown from below, and are gathered between adjacent Group 13 element nitride crystals in the growth process, and the low luminance emission is adjacent on the top surface It is considered that linear bright light-emitting portions were generated between the regions.

For example, FIG. 3 shows a photograph by cathode luminescence measurement of the top surface of the group 13 element nitride crystal layer obtained in the example. 4 is a partial enlarged view of FIG. 3, and FIG. 5 is a schematic view corresponding to FIG. The low brightness light emitting area is two-dimensionally spread in a plane, and the high brightness light emitting portion is linear, and is one-dimensionally stretched like a boundary dividing the adjacent low brightness light emitting areas. I understand that.

From this, the shape of the low luminance light emitting region is not particularly limited, and usually extends two-dimensionally in a planar shape. On the other hand, the line formed by the high luminance light emitting portion needs to be elongated. From such a viewpoint, the width of the high brightness light emitting portion is preferably 100 μm or less, more preferably 20 μm or less, and particularly preferably 5 μm or less. In addition, the width of the high brightness light emitting portion is usually 0.01 μm or more.

From the viewpoint of the present invention, the ratio (length / width) of the length to the width of the high luminance light emitting portion is preferably 1 or more, and more preferably 10 or more.

From the viewpoint of the present invention, the ratio of the area of the high luminance light emitting portion to the area of the low luminance light emitting region on the upper surface (area of high luminance light emitting portion / area of low luminance light emitting region) is 0.001 or more Is more preferably 0.01 or more.
From the viewpoint of the present invention, the ratio of the area of the high luminance light emitting portion to the area of the low luminance light emitting region on the upper surface (area of high luminance light emitting portion / area of low luminance light emitting region) is 0.3 or less Is more preferably 0.1 or less.

In a preferred embodiment, on the upper surface of the Group 13 element nitride crystal layer, the high brightness light emitting portion forms a continuous phase, and the low brightness light emitting region forms a discontinuous phase partitioned by the high brightness light emitting portion. ing. For example, in the schematic views of FIGS. 2 and 5, the linear high brightness light emitting portion 5 forms a continuous phase, and the low brightness light emitting region 6 forms a discontinuous phase partitioned by the high brightness light emitting portion 5. ing.

However, the continuous phase means that the high brightness light emitting portion 5 is continuous on the upper surface, but it is not essential that all the high brightness light emitting portions 5 are completely continuous, and the whole It is to be allowed that a small amount of the high luminance light emitting portion 5 is separated from the other high luminance light emitting portions 5 without affecting the pattern.

Further, the dispersed phase means that the low brightness light emitting region 6 is divided by the high brightness light emitting portion 5 and divided into a large number of regions which are not connected to each other. In addition, even if the low brightness light emitting region 6 is separated by the high brightness light emitting portion 5 on the upper surface, it is acceptable that the low brightness light emitting region 6 is continuous inside the group 13 element nitride crystal layer.

In a preferred embodiment, the high brightness light emitting portion includes a portion extending along the m-plane of the Group 13 element nitride crystal. For example, in the example of FIG. 2, FIG. 5, the high-intensity light emission part 5 is extended in elongate linear form, and contains

many parts

5a, 5b, 5c extended along m surface. Specifically, the directions along the m-plane of Group 13 element nitride crystal, which is a hexagonal crystal, are [-2110], [-12-10], [11-20], and [2-1-10]. The high-intensity light emitting unit 5 includes a part of the side of a substantially hexagonal shape reflecting the hexagonal crystal, which is a [1-210], [-1-120] direction. The linear high-intensity light emitting portion extending along the m-plane means that the longitudinal direction of the high-intensity light emitting portion is [-2110], [-12-10], [11-20], [2- It means extending along one of 1-10 directions, [1-210] and [-1-120] directions. Specifically, the case where the longitudinal direction of the linear high luminance light emitting part is preferably within ± 1 °, more preferably within ± 0.3 ° with respect to the m-plane is included.

The ratio of the portion extending in the direction along the m-plane to the total length of the high luminance light emitting portion is preferably 60% or more, more preferably 80% or more, and substantially occupies the entire high luminance light emitting portion It is also good.

In the first aspect of the present invention, the half width of (0002) plane reflection of the X-ray rocking curve on the top surface of the group 13 element nitride crystal layer is 3000 seconds or less and 20 seconds or more. This indicates that the top surface has a small surface tilt angle, and the crystal orientation as a whole is highly oriented like a single crystal. A characteristic distribution on the upper surface of a Group 13 element nitride crystal layer as having a microstructure in which the crystal orientation on the surface as a whole is highly oriented while having the cathode luminescence distribution as described above It is possible to make the characteristics of the various functional elements provided thereon uniform, and to improve the yield of the functional elements.

From such a viewpoint, the half value width of (0002) plane reflection of the X-ray rocking curve on the top surface of the group 13 element nitride crystal layer is preferably 1000 seconds or less and 20 seconds or more, and 500 seconds or less and 20 seconds or more It is even more preferable that there be. In addition, it is practically difficult to reduce the half width of (0002) plane reflection of the X-ray rocking curve on the upper surface of the group 13 element nitride crystal layer to less than 20 seconds.

However, X-ray rocking curve (0002) surface reflection is measured as follows. Measurement conditions are: tube voltage 40 kV, tube current 40 mA, collimator diameter 0.1 mm, anti-scattering slit 3 mm, using an XRD apparatus (for example, D8-DISCOVER manufactured by Bruker-AXS), ω = peak position angle ± 0.3 ° And the ω step width of 0.003 ° and the counting time of 1 second. In this measurement, it is preferable to parallelize CuKα rays (half-width 28 seconds) with a Ge (022) asymmetric reflection monochromator and measure the axis after setting the axis at a tilt angle CHI of about 0 °. The half width of the X-ray rocking curve (0002) surface reflection can be calculated by performing peak search using XRD analysis software (LEPTOS 4.03 manufactured by Bruker-AXS). The peak search conditions are preferably Noise Filter “10”, Threshold “0.30”, and Points “10”.

When a cross section substantially perpendicular to the top surface of the group 13 element nitride crystal layer is observed by cathode luminescence, as shown in FIG. 6, a linear high-intensity light emitting portion that emits whitish may be observed. In FIG. 6, the low brightness light emitting area is two-dimensionally spread in a planar manner, and the high brightness light emitting portion is linear, and extends like a boundary line which divides adjacent low brightness light emitting areas. Know that The observation method of such a high luminance light emitting portion and the low luminance light emitting region is the same as the observation method of the high luminance light emitting portion and the low luminance light emitting region on the upper surface.

There is no particular limitation on the shape of the low luminance light emitting region in the cross section of the Group 13 element nitride crystal layer, and usually it is two-dimensionally extended in a planar shape. On the other hand, the line formed by the high luminance light emitting portion needs to be elongated. From such a viewpoint, the width of the high brightness light emitting portion is preferably 50 μm or less, and more preferably 10 μm or less.

In a preferred embodiment, in the cross section substantially perpendicular to the top surface of the Group 13 element nitride crystal layer, the linear high luminance light emitting portion forms a continuous phase, and the low luminance light emitting region is formed by the high luminance light emitting portion. It forms a partitioned discontinuous phase. For example, in the cathode luminescence image of FIG. 6, the linear high brightness light emitting portion forms a continuous phase, and the low brightness light emitting region forms a discontinuous phase partitioned by the high brightness light emitting portion.

However, the continuous phase means that the high brightness light emitting portion is continuous in the cross section, but it is not essential that all the high brightness light emitting portions are completely continuous, and the whole pattern It is acceptable that a small amount of high-intensity light emitting portions are separated from other high-intensity light emitting portions without affecting the above.

Further, the dispersed phase means that the low brightness light emitting region is divided by the high brightness light emitting portion and divided into many regions which are not connected to each other.

In a preferred embodiment, no void is observed in a cross section substantially perpendicular to the top surface of the Group 13 element nitride crystal layer. That is, in the scanning electron micrograph shown in FIG. 7, different crystal phases other than voids (voids) and group 13 element nitride crystals are not observed. However, observation of void is performed as follows.

A void is observed when a cross section substantially perpendicular to the top surface of the Group 13 element nitride crystal layer is observed with a scanning electron microscope (SEM), and a void having a maximum width of 1 μm to 500 μm is a “void”. . For this SEM observation, for example, S-3400N scanning electron microscope manufactured by Hitachi High-Technologies Corporation is used. Measurement conditions are preferably observed at an acceleration voltage of 15 kV, a probe current of "60", a working distance (W.D.) of 6.5 mm, and a magnification of 100 times.

In a preferred embodiment, the dislocation density on the top surface of the Group 13 element nitride crystal layer is 1 × 10 ² / cm ² or more and 1 × 10 ⁶ / cm ² or less. It is particularly preferable to set the dislocation density to 1 × 10 ⁶ / cm ² or less from the viewpoint of improving the characteristics of the functional element. From this viewpoint, it is more preferable to set the dislocation density to 1 × 10 ⁴ / cm ² or less. The dislocation density is measured as follows.

For the measurement of dislocation density, a scanning electron microscope (SEM) with a cathode luminescence detector can be used. For example, when using a Hitachi High-Technologies S-3400N scanning electron microscope with Gatan MiniCL system, dislocation sites are observed as dark spots without light emission. Dislocation density is calculated by measuring the dark spot density. As the measurement conditions, while the CL detector is inserted between the sample and the objective lens, it is preferable to observe at an acceleration voltage of 10 kV, a probe current of "90", a working distance (W.D.) 22.5 mm, and a magnification of 1200 times. preferable.

In a preferred embodiment, the half width of (1000) plane reflection of the X-ray rocking curve on the top surface of the group 13 element nitride crystal layer is 10000 seconds or less, 20 seconds or more, and half of (1000) plane reflection. The value range is 10000 seconds or less and 20 seconds or more. This indicates that both the surface tilt angle and the surface twist angle at the upper surface are small, and the crystal orientation is highly oriented as a whole, like a single crystal. With such a fine structure in which the crystal orientation at the surface as a whole is more highly oriented, the characteristic distribution on the upper surface of the group 13 element nitride crystal layer can be reduced, and the characteristics of various functional elements provided thereon Can be made uniform, and the yield of functional devices is also improved.

In the second aspect of the present invention, the half value width of (1000) plane reflection of the X-ray rocking curve on the upper surface of the group 13 element nitride crystal layer is 10000 seconds or less and 20 seconds or more. This means that the surface twist angle at the top surface is very low. It indicates that the crystal orientation as a whole is highly oriented like a single crystal. A characteristic distribution on the upper surface of a Group 13 element nitride crystal layer as having a microstructure in which the crystal orientation on the surface as a whole is highly oriented while having the cathode luminescence distribution as described above It is possible to make the characteristics of the various functional elements provided thereon uniform, and to improve the yield of the functional elements.

From such a viewpoint, the half value width of (1000) plane reflection of the X-ray rocking curve on the upper surface of the group 13 element nitride crystal layer is preferably 5000 seconds or less, more preferably 1000 seconds or less, further 20 seconds or more It is more preferable that In addition, it is practically difficult to reduce this half-width to less than 20 seconds.

However, X-ray rocking curve (1000) surface reflection is measured as follows. Measurement conditions are: tube voltage 40 kV, tube current 40 mA, no collimator, anti-scattering slit 3 mm, range of ω = peak position angle ± 0.3 °, using an XRD apparatus (for example, D8-DISCOVER manufactured by Bruker-AXS) The ω step width may be set to 0.003 ° and the counting time to 4 seconds. In this measurement, it is preferable to measure CuKα rays in parallel monochromatization (half-width 28 seconds) with a Ge (022) asymmetric reflection monochromator and centering around a tilt angle CHI = 88 °. And the half value width of X-ray rocking curve (1000) surface reflection can be calculated by performing peak search using XRD analysis software (manufactured by Bruker-AXS, LEPTOS 4.03). The peak search conditions are preferably Noise Filter “10”, Threshold “0.30”, and Points “10”.

Furthermore, in the first aspect and the second aspect of the present invention, the arithmetic average roughness Ra of the top surface of the group 13 element nitride crystal layer is 0.05 nm or more and 1.0 nm or less.
Arithmetic mean roughness Ra has shown the average value of the absolute value deviation from an average line | wire, and is a numerical value measured according to "JIS0601".

(Example of suitable manufacturing method)
Hereafter, the suitable manufacturing method of a group 13 element nitride crystal layer is illustrated.
The group 13 element nitride crystal layer of the present invention can be produced by forming a seed crystal layer on a base substrate and forming a layer composed of group 13 element nitride crystal thereon.

For example, as illustrated in FIG. 1, the base substrate may be a single crystal substrate 1 on which an alumina layer 2 is formed. Single crystal substrate 1 is a perovskite such as sapphire, AlN template, GaN template, GaN freestanding substrate, SiC single crystal, MgO single crystal, spinel (MgAl ₂ O ₄ ), LiAlO ₂ , LiGaO ₂ , LaAlO ₃ , LaGaO ₃ , NdGaO _{3 and the} like Type composite oxide, SCAM (ScAlMgO ₄ ) can be exemplified. The composition formula _{_{[A 1-y (Sr 1-}} x Ba x) y ] _{_{_{[(Al 1-z Ga z)}}} 1-u · D u ] _O 3 (A is a rare earth element; D is niobium and One or more elements selected from the group consisting of tantalum; y = 0.3 to 0.98; x = 0 to 1; z = 0 to 1; u = 0.15 to 0.49; x + z = 0 The cubic perovskite structure complex oxide of 1) to 2) can also be used.

The alumina layer 2 can be formed by a known technique, and is prepared by sputtering, MBE (molecular beam epitaxy) method, vapor deposition, mist CVD method, sol gel method, aerosol deposition (AD) method, or tape forming. The method of bonding an alumina sheet to the said single crystal substrate is illustrated, and especially the sputtering method is preferable. It is possible to use one to which heat treatment, plasma treatment, or ion beam irradiation has been added after forming the alumina layer, if necessary. The method of heat treatment is not particularly limited, but heat treatment may be performed in an air atmosphere, vacuum, a reducing atmosphere such as hydrogen, or an inert atmosphere such as nitrogen / Ar, a hot press (HP) furnace, a hot isostatic press (HIP) Heat treatment may be performed under pressure using a furnace or the like.

Further, a sapphire substrate to which the same heat treatment, plasma treatment, or ion beam irradiation as described above is added can be used as a base substrate.
Next, as shown in FIG. 1A, for example, a seed crystal layer 3 is provided on the alumina layer 2 or the single crystal substrate 1. The material constituting the seed crystal layer 3 is a nitride of one or two or more kinds of Group 13 elements specified by IUPAC. The group 13 element is preferably gallium, aluminum or indium. Further, specifically, group 13 element nitride crystals are GaN, AlN, InN, Ga _x Al _{1 -x} N (1>x> 0), Ga _x In _1-x N (1>x> 0) And Ga _x Al _y InN _{1 -x-y} (1>x> 0, 1>y> 0).

The method of producing the seed crystal layer 3 is not particularly limited, but MOCVD (organic metal vapor phase growth method), MBE (molecular beam epitaxy method), HVPE (hydride vapor phase growth method), vapor phase method such as sputtering, Na flux method Liquid phase methods such as ammonothermal method, hydrothermal method, sol-gel method, powder method utilizing solid phase growth of powder, and combinations thereof are preferably exemplified.
For example, a seed crystal layer is formed by depositing a low-temperature growth buffer GaN layer at 450 to 550 ° C. for 20 to 50 nm and then laminating a GaN film having a thickness of 2 to 4 μm at 1000 to 1200 ° C. Preferably by

Group 13 element nitride crystal layer 13 is formed to have a crystal orientation substantially conforming to the crystal orientation of seed crystal layer 3. The method of forming the group 13 element nitride crystal layer is not particularly limited as long as it has a crystal orientation substantially following the crystal orientation of the seed crystal film, and a vapor phase method such as MOCVD or HVPE, Na flux method, ammonothermal method, A hydrothermal method, a liquid phase method such as a sol-gel method, a powder method utilizing solid phase growth of powder, and a combination thereof are preferably exemplified, but the Na flux method is particularly preferable.

When forming a Group 13 element nitride crystal layer by Na flux method, it is preferable to strongly stir the melt and mix the melt sufficiently uniformly. As such a stirring method, a swing, rotation, vibration method may be mentioned, but the method is not limited.

Formation of Group 13 element nitride crystal layer by Na flux method, Group 13 metal, metal Na and optionally dopant (for example, germanium (Ge), silicon (Si), oxygen (O), etc., etc. in place of the seed crystal substrate) Filled with a melt composition containing n-type dopants or p-type dopants such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), zinc (Zn) and cadmium (Cd) After heating to 830 ° C. to 910 ° C. and 3.5 to 4.5 MPa in a nitrogen atmosphere, it is preferable to carry out rotation while maintaining the temperature and pressure. The holding time varies depending on the target film thickness, but may be about 10 to 100 hours.

Further, it is preferable to flatten the plate surface by grinding the gallium nitride crystal thus obtained by the Na flux method with a grindstone, and then to smooth the plate surface by lapping using diamond abrasive grains.

(Separation method of Group 13 element nitride crystal layer)
Then, the freestanding substrate including the group 13 element nitride crystal layer can be obtained by separating the group 13 element nitride crystal layer from the single crystal substrate.

Here, the method of separating the group 13 element nitride crystal layer from the single crystal substrate is not limited. In a preferred embodiment, the Group 13 element nitride crystal layer is naturally exfoliated from the single crystal substrate in the temperature lowering step after the Group 13 element nitride crystal layer is grown.

Alternatively, the group 13 element nitride crystal layer can be separated from the single crystal substrate by chemical etching.
As an etchant at the time of chemical etching, a strong acid such as sulfuric acid or hydrochloric acid, a mixed solution of sulfuric acid and phosphoric acid, or a strong alkali such as sodium hydroxide aqueous solution or potassium hydroxide aqueous solution is preferable. Moreover, as for the temperature at the time of performing chemical etching, 70 degreeC or more is preferable.

Alternatively, the group 13 element nitride crystal layer can be separated from the single crystal substrate by a laser lift-off method.
Alternatively, the group 13 element nitride crystal layer can be peeled off from the single crystal substrate by grinding.
Alternatively, the group 13 element nitride crystal layer can be peeled off from the single crystal substrate with a wire saw.

(Self-standing substrate)
A freestanding substrate can be obtained by separating the group 13 element nitride crystal layer from the single crystal substrate. In the present invention, the term "self-supporting substrate" means a substrate which can be handled as a solid without deformation or breakage under its own weight. The self-supporting substrate of the present invention can be used as a substrate for various semiconductor devices such as light emitting elements, but in addition to that, it can be an electrode (may be a p-type electrode or an n-type electrode), a p-type layer, an n-type layer, etc. It can be used as a member or layer other than the base material. This freestanding substrate may further be provided with one or more other layers.

When the group 13 element nitride crystal layer constitutes a self-supporting substrate, the thickness of the self-supporting substrate needs to be able to impart self-supporting properties to the substrate, preferably 20 μm or more, more preferably 100 μm or more, and still more preferably It is 300 μm or more. The upper limit of the thickness of the free-standing substrate should not be defined, but 3000 μm or less is realistic in terms of manufacturing cost.

(How to adjust the arithmetic mean roughness Ra of the upper surface)
The method of adjusting the arithmetic average roughness Ra of the upper surface of the Group 13 element nitride crystal layer to 0.05 to 1.0 nm is not particularly limited, and examples thereof include polishing and etching.
Polishing refers to mechanical polishing, which is processing using loose abrasives, and chemical mechanical polishing (CMP) using colloidal silica or the like. As an etching method, reactive ion etching (RIE) may be mentioned. The etching gas is preferably a chlorine gas or a fluorine gas.

(Composite substrate)
When a group 13 element nitride crystal layer is provided on a single crystal substrate, the group 13 element nitride crystal layer can be used as a template substrate for forming another functional layer without separating the group 13 element nitride crystal layer.

(Functional element)
Although the functional element structure provided on the Group 13 element nitride crystal layer of the present invention is not particularly limited, the light emitting function, the rectifying function or the power control function can be exemplified.
The structure of the light emitting device using the group 13 element nitride crystal layer of the present invention and the method for producing the same are not particularly limited. Typically, a light emitting element is manufactured by providing a light emitting functional layer in a Group 13 element nitride crystal layer. However, a light emitting element is manufactured using the Group 13 element nitride crystal layer as a member or layer other than the base material such as an electrode (which may be a p-type electrode or an n-type electrode), a p-type layer, or an n-type layer. It is also good.

FIG. 8 schematically shows a layer configuration of a light emitting element according to one embodiment of the present invention. A light emitting element 21 shown in FIG. 8 includes a self-supporting substrate 13 and a light emitting functional layer 18 formed on the substrate. The light emitting functional layer 18 provides light emission based on the principle of a light emitting element such as an LED by appropriately providing an electrode or the like and applying a voltage.

The light emitting functional layer 18 is formed on the substrate 13. The light emitting functional layer 18 may be provided on the entire surface or a part of the substrate 13, or may be provided on the entire surface or a part of the buffer layer when the buffer layer described later is formed on the substrate 13. Good. The light emitting functional layer 18 can adopt various known layer configurations that provide light emission based on the principle of a light emitting element represented by an LED by appropriately providing an electrode and / or a phosphor and applying a voltage. Therefore, the light emitting functional layer 18 may emit visible light such as blue and red, or may emit ultraviolet light without visible light or together with visible light. The light emitting functional layer 18 preferably constitutes at least a part of a light emitting element utilizing a pn junction, and the pn junction includes a p-type layer 18a and an n-type layer 18c as shown in FIG. The active layer 18 b may be included between At this time, a double hetero junction or a single hetero junction (hereinafter collectively referred to as a hetero junction) using a layer having a smaller band gap than the p-type layer and / or the n-type layer may be used as the active layer. In addition, a quantum well structure in which the thickness of the active layer is reduced can be employed as one mode of the p-type layer-active layer-n-type layer. It goes without saying that in order to obtain a quantum well, a double hetero junction in which the band gap of the active layer is smaller than that of the p-type layer and the n-type layer should be employed. Further, a multiple quantum well structure (MQW) in which a large number of these quantum well structures are stacked may be used. With these structures, the light emission efficiency can be enhanced as compared to a pn junction. Thus, the light emitting functional layer 18 is preferably provided with a pn junction and / or hetero junction and / or quantum well junction having a light emitting function. 20 and 22 are examples of electrodes.

Therefore, at least one layer constituting the light emitting functional layer 18 is at least selected from the group consisting of an n-type layer doped with an n-type dopant, a p-type layer doped with a p-type dopant, and an active layer. It can be one or more. The n-type layer, the p-type layer and the active layer (if present) may be composed of the same material as the main component or may be composed of materials different from each other in the main component.

The material of each layer constituting the light emitting functional layer 18 is not particularly limited as long as it grows substantially in accordance with the crystal orientation of the group 13 element nitride crystal layer and has a light emitting function, but a gallium nitride (GaN) based material It is preferable to be composed of a material mainly composed of at least one or more selected from zinc oxide (ZnO) based materials and aluminum nitride (AlN) based materials, and a dopant for controlling p type to n type is suitably selected It may be included. Particularly preferred materials are gallium nitride (GaN) based materials. Further, the material constituting the light emitting functional layer 18 may be, for example, a mixed crystal in which AlN, InN or the like is solid-solved in GaN in order to control the band gap. In addition, as described in the immediately preceding paragraph, the light emitting functional layer 18 may be a heterojunction made of a plurality of material systems. For example, a gallium nitride (GaN) based material may be used for the p-type layer, and a zinc oxide (ZnO) based material may be used for the n-type layer. Further, a zinc oxide (ZnO) based material may be used for the p-type layer, and a gallium nitride (GaN) based material may be used for the active layer and the n-type layer, and the combination of materials is not particularly limited.

The film formation method of the light emitting functional layer 18 and the buffer layer is not particularly limited as long as it is a method of growing substantially in accordance with the crystal orientation of the Group 13 element nitride crystal layer, but a vapor phase method such as MOCVD, MBE, HVPE, sputtering, etc. Preferred examples thereof include liquid phase methods such as Na flux method, ammonothermal method, hydrothermal method and sol-gel method, powder method utilizing solid phase growth of powder, and combinations thereof.

Example 1
(Preparation of a gallium nitride free-standing substrate)
An alumina film 2 of 0.3 μm in thickness is formed on a sapphire substrate 1 with a diameter of 6 inches by sputtering, and then a seed crystal film 3 of 2 μm in thickness made of gallium nitride is formed by MOCVD. Obtained.

The seed crystal substrate was placed in an alumina crucible in a nitrogen atmosphere glove box. Next, metallic gallium and metallic sodium were filled in the crucible so that Ga / Ga + Na (mol%) = 15 mol%, and the lid was covered with an alumina plate. The crucible was placed in a stainless steel inner container, further placed in a stainless steel outer container capable of containing it, and closed with a container lid with a nitrogen introduction pipe. The outer container was placed on a rotary table installed in a heating unit in a crystal manufacturing apparatus which has been vacuum baked in advance, and the pressure resistant container was covered and sealed.

Subsequently, the inside of the pressure resistant container was evacuated to 0.1 Pa or less by a vacuum pump. Subsequently, nitrogen gas is introduced from a nitrogen gas cylinder to 4.0 MPa while heating the temperature of the heating space to 870 ° C. by adjusting the upper heater, middle heater and lower heater, and the outer container around the central axis It was rotated at a speed of 20 rpm in a constant cycle clockwise and counterclockwise. The acceleration time was 12 seconds, the holding time was 600 seconds, the deceleration time was 12 seconds, and the stop time was 0.5 seconds. And it hold | maintained in this state for 40 hours. Thereafter, the vessel was naturally cooled to room temperature and depressurized to the atmospheric pressure, and then the lid of the pressure container was opened and the bale was taken out from the inside. The solidified metallic sodium in the crucible was removed, and the crack-free gallium nitride free-standing substrate peeled off from the seed crystal substrate was recovered.

(Evaluation)
When CL observation of the upper surface 13a of the gallium nitride free-standing substrate 13 obtained by polishing processing the gallium nitride surface with a scanning electron microscope (SEM) equipped with a cathode luminescence (CL) detector, the high brightness light emitting portion 5 as shown in FIGS. And the low luminance light emitting area 6 was confirmed.

In addition, the upper surface of the gallium nitride free-standing substrate was polished on a cut surface and observed with a scanning electron microscope (SEM) equipped with a cathode luminescence (CL) detector. As a result, as shown in FIG. 3, in the CL image, a high brightness light emitting portion emitting whitish light was confirmed inside the gallium nitride crystal. However, at the same time, as shown in FIG. 9, when the same field of view was imaged and confirmed with a scanning electron microscope, it was confirmed that a homogeneous gallium nitride crystal was grown without voids.

Further, the gallium nitride free-standing substrate was cut into a cross section perpendicular to the upper surface, and the cut surface was polished and observed with a scanning electron microscope (SEM) equipped with a cathode luminescence (CL) detector. As a result, as shown in FIG. 6, in the CL image, a high luminance light emitting portion emitting whitish light was confirmed inside the gallium nitride crystal. However, at the same time, as shown in FIG. 7, when the same field of view was imaged and confirmed with a scanning electron microscope (SEM), no void etc. were confirmed, and it was confirmed that a homogeneous gallium nitride crystal was grown. That is, even on the top surface of the Group 13 element nitride crystal layer, as in the cross section, the high brightness light emitting portion exists in CL observation but the same shape as the high brightness light emitting portion seen in the same field of view in the SEM There was no microstructure similar to it or that.

(Measurement of dislocation density)
Then, the dislocation density was measured on the top surface of the group 13 element nitride crystal layer. The dislocation density was calculated by performing CL observation and measuring the density of dark spots as dislocation sites. As a result of observing five 80 μm × 105 μm fields of view, they varied within a range of 1.2 × 10 ⁴ / cm ² to 9.4 × 10 ⁴ / cm ² , and were 3.3 × 10 ⁴ / cm ² on average.

(Measurement of surface tilt angle)
It was 73 seconds as a result of measuring the half value width of (0002) plane reflection of the X ray rocking curve in the upper surface of a gallium nitride crystal layer.

(Measurement of surface twist angle)
It was 85 seconds when the half value width of (1000) plane reflection of the X-ray rocking curve in the upper surface of the gallium nitride crystal layer was measured.

(Arithmetic mean roughness Ra)
Arithmetic mean roughness Ra of the upper surface of the obtained free-standing substrate was measured with an atomic force microscope (model: AFM5400L) manufactured by Hitachi High-Tech Science. As a cantilever, MICRO CANTILEVER OMCL-AC160TS-C3 manufactured by OLYMPUS was used. The measurement conditions were a dynamic focus mode, a scanning frequency of 0.81 Hz, and a visual field of 10 × 10 μm. We used Nano Navi Real for analysis software. As a result, Ra was 0.08 nm.

(Deposition of light emitting functional layer by MOCVD method)
Using an MOCVD method, an n-type n-type layer was deposited 1 μm as an n-type layer at 1050 ° C. to have a Si atomic concentration of 5 × 10 ¹⁸ / cm ³ as the n-type layer. Next, a multiple quantum well layer was deposited at 750 ° C. as a light emitting layer. Specifically, five layers of 2.5 nm well layers of InGaN and six layers of 10 nm of barrier layers of GaN were alternately stacked. Next, as a p-type layer, 200 nm of p-GaN doped at a temperature of 950 ° C. so that the Mg atom concentration is 1 × 10 ¹⁹ / cm ³ was deposited. Thereafter, it was taken out of the MOCVD apparatus, and heat treatment at 800 ° C. in a nitrogen atmosphere was performed for 10 minutes as activation treatment of Mg ions in the p-type layer.
No pits were observed on the surface of the obtained light emitting functional layer.

(Fabrication of light emitting element)
15 nm and 70 nm Ti / Al / Ni / Au film as cathode electrode on the opposite side of n-GaN layer and p-GaN layer of gallium nitride freestanding substrate by photolithography process and vacuum evaporation method It patterned in thickness of 12 nm and 60 nm. Thereafter, heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds in order to improve ohmic contact characteristics. Further, a Ni / Au film was patterned to a thickness of 6 nm and 12 nm as a light transmitting anode electrode in the p-type layer using a photolithography process and a vacuum evaporation method. Thereafter, a heat treatment at 500 ° C. was performed for 30 seconds in a nitrogen atmosphere in order to improve ohmic contact characteristics. Furthermore, using a photolithography process and a vacuum evaporation method, the Ni / Au film to be the anode electrode pad has a thickness of 5 nm and 60 nm, respectively, on a partial region of the upper surface of the Ni / Au film as the translucent anode electrode. Patterned. The substrate thus obtained was cut into chips, and then mounted on lead frames to obtain light emitting elements of a vertical structure.

(Evaluation of light emitting element)
When current was applied between the cathode electrode and the anode electrode, and IV measurement was carried out for 100 individuals arbitrarily selected from the manufactured elements, rectification was confirmed for 90 pieces. In addition, when forward current flowed, emission of wavelength 460 nm was confirmed.

(Adjustment of the arithmetic mean roughness Ra on the upper surface and deposition of the light emitting functional layer)
The upper surface of the obtained free-standing substrate was polished to adjust the arithmetic mean roughness Ra to 0.05, 0.1, and 1.0 nm, respectively. However, Ra was adjusted as follows.
The upper surface with Ra of 0.05 nm is adjusted by CMP, the upper surface with Ra of 0.1 nm is adjusted with RIE, and the upper surface with Ra of 1.0 nm is adjusted by mechanical polishing. did.
Next, the light emitting functional layer was epitaxially grown on the upper surface of each freestanding substrate by the MOCVD method as described above. As a result, no surface pit was observed in any case.

(Creation of rectification function element)
A functional element having a rectifying function was produced.
That is, a Schottky barrier diode structure was formed as follows on the upper surface of the freestanding substrate obtained in the example, and an electrode was formed to obtain a diode, and the characteristics were confirmed.

(Deposition of rectifying function layer by MOCVD method)
A 5 μm thick n-GaN layer doped as an n-type layer at 1050 ° C. and having a Si atomic concentration of 1 × 10 ¹⁶ / cm ³ on a free-standing substrate using MOCVD (metal organic chemical vapor deposition) method I made a film.

Ti / Al / Ni / Au films with a thickness of 15 nm, 70 nm, 12 nm, and 60 nm as ohmic electrodes on the surface of the free-standing substrate opposite to the n-GaN layer using photolithography process and vacuum evaporation method Patterned. Thereafter, heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds in order to improve ohmic contact characteristics. Further, a Ni / Au film was patterned as a Schottky electrode to a thickness of 6 nm and 80 nm, respectively, on the n-GaN layer formed by the MOCVD method using a photolithography process and a vacuum evaporation method. The substrate obtained in this manner was cut into chips, and then mounted on lead frames to obtain rectifying devices.

(Evaluation of rectifier)
When the IV measurement was performed, the rectification characteristic was confirmed.

(Creating a power control element)
A functional element having a power control function was produced.
A self-supporting substrate was produced in the same manner as in the above example. However, unlike Example 1, when forming a gallium nitride crystal film by Na flux method, doping of impurities was not performed. The upper surface of the free-standing substrate obtained in this manner, in the following manner, forming a Al _0.25 Ga _{0.75 N} / GaN HEMT structure by MOCVD to form the electrodes was confirmed transistor characteristics.

Using an MOCVD (metal organic chemical vapor deposition) method, a 3 μm-thick GaN layer was formed as an i-type layer at 1050 ° C. as an i-type layer on a free-standing substrate. Next, a 25 nm Al _0.25 Ga _0.75 N layer was deposited at 1050 ° C. as a functional layer. This resulted in an Al _0.25 Ga _0.75 N / GaN HEMT structure.

Ti / Al / Ni / Au films as source and drain electrodes were patterned to thicknesses of 15 nm, 70 nm, 12 nm, and 60 nm, respectively, using a photolithography process and a vacuum evaporation method. Thereafter, heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds in order to improve ohmic contact characteristics. Furthermore, using a photolithography process and a vacuum evaporation method, a Ni / Au film as a gate electrode was formed by Schottky junction with a thickness of 6 nm and 80 nm, respectively, and patterned. The substrate thus obtained was cut into chips, and then mounted on lead frames to obtain power control elements.

(Evaluation of power control element)
When the IV characteristics were measured, good pinch-off characteristics were confirmed, and the maximum drain current was 710 mA / mm, and the maximum transconductance was 210 mS / mm.

The upper surface of the Group 13 element nitride crystal in the present embodiment is an N-face, but the same effect can be obtained with a Ga-face.

Claims

13. Group 13 element nitride crystal layer comprising a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or mixed crystals thereof, having a top surface and a bottom surface,
When the upper surface is observed by cathode luminescence, it has a high brightness light emitting portion and a low brightness light emitting region adjacent to the high brightness light emitting portion,
The half value width of (0002) plane reflection of the X-ray rocking curve on the upper surface is 3000 seconds or less and 20 seconds or more,
Arithmetic mean roughness Ra of the upper surface is 0.05 nm or more and 1.0 nm or less, and the group 13 element nitride layer is characterized.
The group 13 element nitride crystal layer according to claim 1, wherein no void is observed in a cross section substantially perpendicular to the upper surface of the group 13 element nitride crystal layer.
The group 13 element nitride crystal layer according to claim 1 or 2, wherein a dislocation density on the upper surface of the group 13 element nitride crystal layer is 1 × 10 6 / cm 2 or less.
The group 13 element nitrided according to claim 3, wherein the dislocation density on the upper surface of the group 13 element nitride crystal layer is 1 x 10 2 / cm 2 or more and 1 x 10 6 / cm 2 or less. Crystal layer.
The high brightness light emitting portion forms a continuous phase, and the low brightness light emitting region forms a discontinuous phase partitioned by the high brightness light emitting portion. A group 13 element nitride crystal layer according to any one of the claims.
The group 13 element nitrided according to any one of claims 1 to 5, wherein the high brightness light emitting portion includes a portion extending along the m-plane of the group 13 element nitride crystal. Crystal layer.
The group 13 element according to any one of claims 1 to 6, wherein a half value width of (1000) plane reflection of the X-ray rocking curve on the upper surface is 10000 seconds or less and 20 seconds or more. Nitride layer.
The Group 13 element nitride layer according to any one of claims 1 to 7, wherein the Group 13 element nitride is a gallium nitride based nitride.
A freestanding substrate comprising the group 13 element nitride layer according to any one of claims 1 to 8.
A functional device comprising: the self-supporting substrate according to claim 9; and a functional layer provided on the group 13 element nitride layer.
The functional device according to claim 10, wherein the function of the functional layer is a light emitting function, a rectifying function or a power control function.
A composite substrate, comprising: a support substrate; and the Group 13 element nitride layer according to any one of claims 1 to 8 provided on the support substrate.
A functional device comprising the composite substrate according to claim 12 and a functional layer provided on the group 13 element nitride layer.
The functional device according to claim 13, wherein the function of the functional layer is a light emitting function, a rectifying function or a power control function.
13. Group 13 element nitride crystal layer comprising a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or mixed crystals thereof, having a top surface and a bottom surface,
When the upper surface is observed by cathode luminescence, it has a high brightness light emitting portion and a low brightness light emitting region adjacent to the high brightness light emitting portion,
The half value width of (1000) plane reflection of the X-ray rocking curve on the upper surface is 10000 seconds or less and 20 seconds or more,
Arithmetic mean roughness Ra of the upper surface is 0.05 nm or more and 1.0 nm or less, and the group 13 element nitride layer is characterized.
The group 13 element nitride crystal layer according to claim 15, wherein no void is observed in a cross section substantially perpendicular to the upper surface of the group 13 element nitride crystal layer.
The group 13 element nitride crystal layer according to claim 15 or 16, wherein a dislocation density on the upper surface of the group 13 element nitride crystal layer is 1 × 10 6 / cm 2 or less.
The group 13 element nitrided according to claim 17, wherein the dislocation density on the upper surface of the group 13 element nitride crystal layer is 1 x 10 2 / cm 2 or more and 1 x 10 6 / cm 2 or less. Crystal layer.
19. The high-intensity light emitting portion forms a continuous phase, and the low-intensity light emitting region forms a discontinuous phase partitioned by the high-intensity light emitting portion. A group 13 element nitride crystal layer according to any one of the claims.
20. The group 13 element nitrided according to any one of claims 15 to 19, wherein the high brightness light emitting portion includes a portion extending along the m-plane of the group 13 element nitride crystal. Crystal layer.
The group 13 element nitride layer according to any one of claims 15 to 20, wherein the group 13 element nitride is a gallium nitride based nitride.
A freestanding substrate comprising the group 13 element nitride layer according to any one of claims 15 to 21.
A functional element comprising: the self-supporting substrate according to claim 22; and a functional layer provided on the group 13 element nitride layer.
The functional device according to claim 23, wherein the function of the functional layer is a light emitting function, a rectifying function or a power control function.
A composite substrate comprising: a support substrate; and the group 13 element nitride layer according to any one of claims 15 to 21 provided on the support substrate.
A functional element comprising: the composite substrate according to claim 25; and a functional layer provided on the group 13 element nitride layer.
The functional device according to claim 26, wherein the function of the functional layer is a light emitting function, a rectifying function or a power control function.