JPWO2019039208A1 - Group 13 element nitride layer, self-supporting substrate and functional element - Google Patents

Abstract

When the upper surface 13a of the Group 13 element nitride crystal layer 13 is observed by cathodoluminescence, it has a linear high-intensity light emitting unit 5 and a low-intensity light-emitting region 6 adjacent to the high-intensity light-emitting unit 5. The half width of the (0002) surface reflection of the X-ray locking curve on the upper surface 13a is 3000 seconds or less and 20 seconds or more, and the arithmetic mean roughness Ra of the upper surface 13a is 0.05 nm or more and 1.0 nm or less. [Selection diagram] Fig. 1

Description

The present invention relates to a Group 13 elemental nitride layer, a self-supporting substrate and a functional element.

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 a quantum well layer composed of an InGaN layer and a barrier layer composed of a GaN layer are alternately laminated, and a p-type GaN layer are sequentially laminated and formed. Those with a similar structure have been 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. Further, the average tilt angle on the surface (the average value of the inclination of the crystal orientation (crystal axis) in the normal direction with respect to the surface) is 1 to 10 °.

In Patent Document 3, a plurality of grain boundaries containing a high concentration of inclusions from the bottom surface to the intermediate position and a low concentration from the intermediate position to the upper surface are formed in an oblique direction from the lower surface. In addition, the grain boundaries extend diagonally in a 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 can be obtained by increasing the Ga ratio in the melt.

Patent No. 5770905 Patent No. 6154066 Patent No. 5897790 WO 2011/046203 WO2010 / 084682

When a light emitting device is formed on the gallium nitride crystals of Patent Documents 1 and 2, the current path may be blocked and the luminous efficiency may be lowered depending on the balance between the device size and the particle size. It has become clear. The reason for this is not clear, but it is possible that the anisotropy of the orientation between the single crystal particles is 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 voids may remain on the outer periphery of the crystal.

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

An object of the present invention is to reduce the dislocation density in a group 13 element nitride crystal layer having a top surface and a bottom surface, which comprises a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof. It is possible to provide a microstructure that can reduce the variation in characteristics throughout.

A first aspect of the present invention is a group 13 element nitride crystal layer composed of a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof, and having a top surface and a bottom surface. ,
When the upper surface is observed by cathodoluminescence, it has a linear high-intensity light emitting portion and a low-intensity light emitting region adjacent to the high-intensity light emitting portion.
The half width of the (0002) plane reflection of the X-ray locking curve on the upper surface is 3000 seconds or less and 20 seconds or more.
The arithmetic average roughness Ra of the upper surface is 0.05 nm or more and 1.0 nm or less.

A second aspect of the present invention is a group 13 element nitride crystal layer composed of a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof, and having an upper surface and a bottom surface. There,
When the upper surface is observed by cathodoluminescence, it has a high-intensity light emitting portion and a low-intensity light emitting region adjacent to the high-intensity light emitting portion.
The half width of the (1000) surface reflection of the X-ray locking curve on the upper surface is 10,000 seconds or less and 20 seconds or more.
The arithmetic average 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, which comprises the above-mentioned group 13 element nitride layer.

In addition, the present invention
The present invention relates to a composite substrate, which comprises a support substrate and the group 13 element nitride layer provided on the support substrate.

The present invention also relates to a functional element having the self-supporting substrate and a functional layer provided on the group 13 element nitride layer.

The present invention also relates to a functional element having 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 upper surface of the group 13 element nitride crystal layer is observed by cathodoluminescence, a linear high-intensity light emitting portion and a low-intensity light emitting region adjacent to the high-intensity light emitting portion And the half-value width of the (0002) plane reflection of the X-ray locking curve on the upper surface is 3000 seconds or less and 20 seconds or more. This is because the linear high-intensity light-emitting part appears on the upper surface, so that the linear high-intensity light-emitting part in which the dopant component and the trace component contained in the group 13 element nitride crystal are dense 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 almost 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 cathodoluminescence, a linear high-intensity light emitting portion and a low-intensity light emitting region adjacent to the high-intensity light-emitting portion The half-value width of the (1000) plane reflection of the X-ray locking curve on the upper surface of the group 13 element nitride crystal layer is 10,000 seconds or less and 20 seconds or more. This means that since the linear high-intensity light-emitting part appears on the upper surface, the dopant component contained in the Group 13 element nitride crystal produces a very dense linear high-intensity light-emitting part. doing. At the same time, since the average twist angle on the upper surface is small and the orientations of the crystal axes are almost aligned, a very homogeneous microstructure similar to a single crystal is obtained.

With the group 13 element nitride crystal layer having a novel microstructure like these, even if the size is increased (for example, even if the diameter is 6 inches or more), the dislocation density can be reduced and the variation in characteristics can be reduced as a whole. A group 13 element nitride crystal layer can be provided.
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. As a result, the generation of surface pits can be suppressed when a functional element layer such as an LD element or an LED element is epitaxially grown on the upper surface of the Group 13 element nitride crystal layer.

(A) shows a 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 the group 13 element nitride separated from the support substrate. The crystal layer 13 is shown. It is a schematic diagram for demonstrating the cathode luminescence image of the upper surface 13a of the group 13 element nitride crystal layer 13. It is a photograph which shows the cathode luminescence image of the upper surface 13a of the group 13 element nitride crystal layer 13. It is a partially 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 cross section of the group 13 element nitride crystal layer 13. It is a scanning electron micrograph which shows the cross section of the 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 photograph taken by a scanning electron microscope on the upper surface of the group 13 element nitride crystal layer. A grayscale histogram generated from the CL image is shown.

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 a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof, and has an upper surface and a bottom surface. For example, as shown in FIG. 1B, in the group 13 element nitride crystal layer 13, the upper 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 a mixed crystal 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). >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, 1>y> 0.3, x + y + z = 1).

The group 13 element nitride may be doped with zinc, calcium or other n-type dopant or p-type dopant. In this case, the polycrystalline group 13 element nitride may be doped with a p-type electrode, an n-type electrode, or p. It can be used as a member or layer other than a base material 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, as schematically shown in FIG. 2, the linear high-intensity light emitting unit 5 and the high-intensity light-emitting unit 5 are adjacent to each other. It has a low-luminance light emitting region 6 and the like.

However, observation by cathodoluminescence (CL) shall be performed as follows.
A scanning electron microscope (SEM) equipped with a cathodoluminescence detector is used for CL observation. For example, when a Hitachi High-Technologies S-3400N scanning electron microscope with a Gatan MiniCL system is used, the measurement conditions are an acceleration voltage of 10 kV and a probe current of "90" with the CL detector inserted between the sample and the objective lens. It is preferable to observe at a working distance (WD) of 22.5 mm and a magnification of 50 times.
Further, the high-intensity light emitting portion and the low-intensity light-emitting region are distinguished from the observation by cathodoluminescence as follows.
Image analysis software (for example, WinROOF Ver6.1 manufactured by Mitani Shoji Co., Ltd.) determines the brightness of the CL observed image with an acceleration voltage of 10 kV, a probe current of "90", a working distance (WD) of 22.5 mm, and a magnification of 50 times. Using 3.3), a 256-step grayscale histogram is created with the vertical axis representing the frequency and the horizontal axis representing the luminance (GRAY). As shown in FIG. 10, two peaks are confirmed in the histogram, and the high side is defined as the high-intensity light emitting part and the low side is defined as the low-intensity light-emitting region with the brightness at which the frequency is the minimum value between the two peaks as a boundary. To do.

Further, on the upper surface of the Group 13 element nitride crystal layer, a low-luminance light emitting region is adjacent to a linear high-luminance light emitting portion. As a result, the adjacent low-brightness light emitting regions are separated by the linear high-brightness light emitting portion between them. Here, the linear high-luminance light emitting portion indicates a state in which the high-luminance light emitting portion is elongated and forms a boundary line between adjacent low-luminance light emitting regions.

Here, the line formed by the high-luminance light emitting unit 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 an arc, an ellipse, a parabola, and a hyperbola. Further, the high-luminance light emitting portions having different directions may be continuous, but the end of the high-luminance light emitting portion may be cut off.

On 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 that has grown beneath the exposed surface, and extends two-dimensionally in a planar manner. On the other hand, although the high-luminance light emitting portion has a linear shape, it extends unilaterally like a boundary line that divides adjacent low-luminance light emitting regions. This is because, for example, dopant components, trace components, etc. are discharged from the Group 13 element nitride crystals that have grown from below, gather between adjacent Group 13 element nitride crystals during the growth process, and emit low-intensity light that is adjacent on the upper surface. It is probable that a portion that emits strong light linearly was generated between the regions.

For example, FIG. 3 shows a photograph of the upper surface of the Group 13 element nitride crystal layer obtained in the example by cathodoluminescence measurement. FIG. 4 is a partially enlarged view of FIG. 3, and FIG. 5 is a schematic view corresponding to FIG. The low-intensity light emitting region extends two-dimensionally in a plane shape, and the high-intensity light emitting portion has a linear shape, and extends one-dimensionally like a boundary line that divides adjacent low-luminance light emitting regions. You can see that.

From this, there is no particular limitation on the shape of the low-luminance light emitting region, and it is usually planar and two-dimensionally extended. On the other hand, the line formed by the high-luminance light emitting portion needs to be elongated. From this point of view, the width of the high-luminance light emitting portion is preferably 100 μm or less, more preferably 20 μm or less, and particularly preferably 5 μm or less. Further, the width of the high-luminance light emitting portion is usually 0.01 μm or more.

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

Further, from the viewpoint of the present invention, the ratio of the area of the high-intensity light emitting portion to the area of the low-intensity light emitting region (area of the high-intensity light emitting portion / area of the low-intensity light emitting region) is 0.001 or more on the upper surface. It is preferable, and more preferably 0.01 or more.
From the viewpoint of the present invention, the ratio of the area of the high-intensity light emitting portion to the area of the low-intensity light emitting region (area of the high-intensity light emitting portion / area of the low-intensity light emitting region) is 0.3 or less on the upper surface. It is preferable, and more preferably 0.1 or less.

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

However, the continuous phase means that the high-intensity light emitting unit 5 is continuous on the upper surface, but it is not essential that all the high-intensity light emitting units 5 are completely continuous, and the whole It is permissible that a small amount of the high-intensity light emitting unit 5 is separated from the other high-intensity light emitting unit 5 within a range that does not affect the pattern.

Further, the dispersed phase means that the low-luminance light emitting region 6 is generally partitioned by the high-luminance light emitting unit 5 and is divided into a large number of regions that are not connected to each other. Further, even if the low-luminance light emitting region 6 is separated by the high-luminance light emitting unit 5 on the upper surface, it is permissible that the low-luminance light emitting region 6 is continuous inside the group 13 element nitride crystal layer.

In a preferred embodiment, the high-intensity light emitting portion includes a portion extending along the m-plane of the Group 13 element nitride crystal. For example, in the examples of FIGS. 2 and 5, the high-luminance light emitting portion 5 extends in an elongated linear shape, and includes many portions 5a, 5b, and 5c extending along the m-plane. The directions along the m-plane of the hexagonal group 13 element nitride crystal are specifically [-2110], [-12-10], [11-20], [2-1-10]. , [1-210], [-1-120], and the high-intensity light emitting unit 5 includes a part of the side of a substantially hexagon reflecting a hexagonal crystal. In addition, the linear high-intensity light-emitting part extends along the m-plane means that the longitudinal direction of the high-intensity light-emitting part is [-2110], [-12-10], [11-20], [2- It means that it extends along one of the directions 1-10], [1-210], and [-1-120]. Specifically, this includes a case where the longitudinal direction of the linear high-luminance light emitting portion is preferably within ± 1 °, more preferably within ± 0.3 ° with respect to the m-plane.

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-intensity light emitting portion. May be good.

In the first aspect of the present invention, the half width of the (0002) plane reflection of the X-ray locking curve on the upper surface of the Group 13 element nitride crystal layer is 3000 seconds or less and 20 seconds or more. This indicates that the surface tilt angle is small on the upper surface, and the crystal orientation is highly oriented like a single crystal as a whole. In addition to having the cathodoluminescence distribution as described above, if the microstructure has a highly oriented crystal orientation on the surface as a whole, the characteristic distribution on the upper surface of the group 13 element nitride crystal layer. Can be made smaller, the characteristics of various functional elements provided on the functional elements can be made uniform, and the yield of the functional elements can be improved.

From this point of view, the half width of the (0002) plane reflection of the X-ray locking curve on the upper 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 to have. It is practically difficult to reduce the half width of the (0002) plane reflection of the X-ray locking curve on the upper surface of the Group 13 element nitride crystal layer to less than 20 seconds.

However, the X-ray locking curve (0002) plane reflection is measured as follows. Using an XRD device (for example, D8-DISCOVER manufactured by Bruker-AXS), the measurement conditions are tube voltage 40 kV, tube current 40 mA, collimator diameter 0.1 mm, anti-scattering slit 3 mm, and ω = peak position angle ± 0.3 °. The range, the ω step width of 0.003 °, and the counting time of 1 second may be set. In this measurement, it is preferable to convert CuKα rays into parallel monochromatic light (half-value width 28 seconds) with a Ge (022) asymmetric reflection monochromator, and to perform the measurement after axially tilting the tilt angle at around CHI = 0 °. Then, the full width at half maximum of the X-ray locking curve (0002) surface reflection can be calculated by performing a peak search using XRD analysis software (manufactured by Bruker-AXS, LEPTOS 4.03). The peak search conditions are preferably Noise Filter "10", Thrashold "0.30", and Points "10".

When the cross section substantially perpendicular to the upper surface of the Group 13 element nitride crystal layer is observed by cathodoluminescence, as shown in FIG. 6, a linear high-intensity light emitting portion that emits whitish light may be observed. In FIG. 6, the low-luminance light emitting region is spread two-dimensionally in a plane shape, and the high-luminance light emitting portion is linear, extending like a boundary line for dividing adjacent low-luminance light emitting regions. You can see that. The method of observing the high-intensity light emitting unit and the low-intensity light emitting region is the same as the observation method of the high-intensity light-emitting part and the low-intensity light-emitting region on the upper surface.

The shape of the low-luminance light emitting region in the cross section of the Group 13 element nitride crystal layer is not particularly limited, and is usually planar and two-dimensionally extended. On the other hand, the line formed by the high-luminance light emitting portion needs to be elongated. From this point of view, the width of the high-luminance 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 upper surface of the Group 13 element nitride crystal layer, the linear high-intensity light-emitting portion forms a continuous phase, and the low-intensity light-emitting region is formed by the high-intensity light-emitting portion. It forms a partitioned discontinuous phase. For example, in the cathode luminescence image of FIG. 6, the linear high-luminance light emitting portion forms a continuous phase, and the low-luminance light emitting region forms a discontinuous phase defined by the high-luminance light emitting portion.

However, although the continuous phase means that the high-luminance light emitting parts are continuous in the cross section, it is not essential that all the high-luminance light emitting parts are completely continuous, and the entire pattern is not required. It is permissible that a small amount of high-intensity light-emitting part is separated from other high-intensity light-emitting parts within a range that does not affect the above.

Further, the dispersed phase means that the low-luminance light emitting region is generally divided by the high-luminance light emitting portion and is divided into a large number of regions that are not connected to each other.

In a preferred embodiment, no voids are 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, no different crystal phases other than voids and Group 13 element nitride crystals are observed. However, voids are observed as follows.

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

Further, in a preferred embodiment, the dislocation density on the upper 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 that the dislocation density is 1 × 10 ⁶ / cm ² or less from the viewpoint of improving the characteristics of the functional element. From this point of view, it is more preferable that the dislocation density is 1 × 10 ⁴ / cm ² or less. This dislocation density shall be measured as follows.

A scanning electron microscope (SEM) with a cathodoluminescence detector can be used to measure the dislocation density. For example, when a Hitachi High-Technologies S-3400N scanning electron microscope equipped with a Gatan MiniCL system is used, the dislocations are observed as black spots (dark spots) without emitting light. The dislocation density is calculated by measuring the dark spot density. The measurement conditions are to observe with the CL detector inserted between the sample and the objective lens at an accelerating voltage of 10 kV, a probe current of "90", a working distance (WD) of 22.5 mm, and a magnification of 1200 times. preferable.

Further, in a preferred embodiment, the half width of the (1000) plane reflection of the X-ray locking curve on the upper surface of the Group 13 element nitride crystal layer is 10,000 seconds or less, 20 seconds or more, and half of the (1000) plane reflection. The price range is 10,000 seconds or less and 20 seconds or more. This indicates that both the surface tilt angle and the surface twist angle on the upper surface are small, and the crystal orientation as a whole is more highly oriented like a single crystal. With such a microstructure in which the crystal orientation on the surface is more highly oriented as a whole, 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 on the microstructure can be reduced. Can be uniformly aligned, and the yield of functional elements is also improved.

In the second aspect of the present invention, the half width of the (1000) plane reflection of the X-ray locking curve on the upper surface of the Group 13 element nitride crystal layer is 10,000 seconds or less and 20 seconds or more. This means that the surface twist angle on the top surface is very low. It shows that the crystal orientation is highly oriented like a single crystal as a whole. In addition to having the cathodoluminescence distribution as described above, if the microstructure has a highly oriented crystal orientation on the surface as a whole, the characteristic distribution on the upper surface of the group 13 element nitride crystal layer. Can be made smaller, the characteristics of various functional elements provided on the functional elements can be made uniform, and the yield of the functional elements can be improved.

From this point of view, the half width of the (1000) plane reflection of the X-ray locking 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, and further 20 seconds or more. Is more preferable. Moreover, it is practically difficult to reduce this half width to less than 20 seconds.

However, the X-ray locking curve (1000) surface reflection is measured as follows. Using an XRD device (for example, D8-DISCOVER manufactured by Bruker-AXS), the measurement conditions are tube voltage 40 kV, tube current 40 mA, no collimator, anti-scattering slit 3 mm, ω = peak position angle ± 0.3 ° range, The ω step width may be set to 0.003 ° and the counting time may be set to 4 seconds. In this measurement, it is preferable to convert CuKα rays into parallel monochromatic light (half-value width 28 seconds) with a Ge (022) asymmetric reflection monochromator, and to perform the measurement after axially tilting the tilt angle at around CHI = 88 °. Then, the full width at half maximum of the X-ray locking curve (1000) surface reflection can be calculated by performing a peak search using XRD analysis software (manufactured by Bruker-AXS, LEPTOS 4.03). The peak search conditions are preferably Noise Filter "10", Thrashold "0.30", and Points "10".

Further, in the first aspect and the second aspect of the present invention, 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.
The arithmetic mean roughness Ra indicates the average value of the absolute value deviation from the average line, and is a numerical value measured according to "JIS0601".

(Example of suitable manufacturing method)
Hereinafter, a suitable method for producing the Group 13 element nitride crystal layer will be 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 crystals on the seed crystal layer.

For example, as illustrated in FIG. 1, as the base substrate, one in which the alumina layer 2 is formed on the single crystal substrate 1 can be used. The single crystal substrate 1 is a perovskite such as sapphire, AlN template, GaN template, GaN free-standing substrate, SiC single crystal, MgO single crystal, spinel (MgAl ₂ O ₄ ), LiAlO ₂ , LiGaO ₂ , LaAlO ₃ , LaGaO ₃ , NdGaO _3. A 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 A cubic perovskite structure composite oxide of 1 to 2) can also be used.

A known technique can be used for forming the alumina layer 2, and the alumina layer 2 is produced by sputtering, MBE (molecular beam epitaxy) method, thin film deposition, mist CVD method, sol-gel method, aerosol deposition (AD) method, tape molding, or the like. A method of bonding the alumina sheet to the single crystal substrate is exemplified, and the sputtering method is particularly preferable. If necessary, an alumina layer to which heat treatment, plasma treatment, or ion beam irradiation is applied after being formed can be used. The method of heat treatment is not particularly limited, but the heat treatment may be performed in an atmospheric atmosphere, a vacuum, a reducing atmosphere such as hydrogen, or an inert atmosphere such as nitrogen / Ar, and a hot press (HP) furnace or a hot hydrostatic press (HIP) may be used. ) The heat treatment may be performed under pressure using a furnace or the like.

Further, as the base substrate, a sapphire substrate subjected to the same heat treatment, plasma treatment, and ion beam irradiation as described above can also be used.
Next, for example, as shown in FIG. 1A, the 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 one or more nitrides of Group 13 elements specified by IUPAC. The Group 13 element is preferably gallium, aluminum or indium. Specifically, the 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). , Ga _x Al _y InN _1-xy (1>x> 0, 1>y> 0) is preferable.

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

The Group 13 element nitride crystal layer 13 is formed so as to have a crystal orientation that roughly follows the crystal orientation of the seed crystal layer 3. The method for forming the Group 13 element nitride crystal layer is not particularly limited as long as it has a crystal orientation that roughly follows the crystal orientation of the seed crystal film, and is a vapor phase method such as MOCVD and HVPE, a Na flux method, and an amonothermal method. A liquid phase method such as a hydrothermal method and a solgel method, a powder method utilizing solid phase growth of a powder, and a combination thereof are preferably exemplified, but the Na flux method is particularly preferable.

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

The formation of the Group 13 element nitride crystal layer by the Na flux method involves forming a Group 13 metal, metal Na, and optionally a dopant (eg, germanium (Ge), silicon (Si), oxygen (O), etc.) in a pit on which the seed crystal substrate is placed. , Or a melt composition containing beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), zinc (Zn), cadmium (Cd) and other p-type dopants). It is preferable that the temperature and pressure are raised and pressurized to 830 to 910 ° C. and 3.5 to 4.5 MPa in a nitrogen atmosphere, and then the rotation is performed 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 that the gallium nitride crystal thus obtained by the Na flux method is ground with a grindstone to flatten the plate surface, and then the plate surface is smoothed by a lapping process using diamond abrasive grains.

(Method for separating Group 13 element nitride crystal layer)
Next, by separating the Group 13 element nitride crystal layer from the single crystal substrate, a self-supporting substrate containing the Group 13 element nitride crystal layer can be obtained.

Here, the method for 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 peeled 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 the etchant for 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 an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution is preferable. The temperature at which chemical etching is performed is preferably 70 ° C. or higher.

Alternatively, the Group 13 element nitride crystal layer can be peeled off 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-supporting board)
A free-standing substrate can be obtained by separating the Group 13 element nitride crystal layer from the single crystal substrate. In the present invention, the "self-supporting substrate" means a substrate that can be handled as a solid substance without being deformed or damaged by its own weight when handled. The self-supporting substrate of the present invention can be used as a substrate for various semiconductor devices such as light emitting elements, but other than that, electrodes (which may be p-type electrodes or n-type electrodes), p-type layers, n-type layers, etc. It can be used as a member or layer other than the base material. The self-supporting substrate may be further provided with other layers than one layer.

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 independence to the substrate, and is preferably 20 μm or more, more preferably 100 μm or more, still more preferably. It is 300 μm or more. An upper limit should not be specified for the thickness of the self-supporting substrate, but from the viewpoint of manufacturing cost, 3000 μm or less is realistic.

(How to adjust the arithmetic mean roughness Ra on the upper surface)
The method for adjusting the arithmetic mean 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 free abrasive grains, and chemical mechanical polishing (CMP), which uses colloidal silica or the like. Etching methods include reactive ion etching (RIE). Chlorine-based or fluorine-based gas is preferable as the etching gas.

(Composite board)
With the Group 13 element nitride crystal layer provided on the single crystal substrate, it can be used as a template substrate for forming another functional layer without separating the Group 13 element nitride crystal layer.

(Functional element)
The functional element structure provided on the Group 13 element nitride crystal layer of the present invention is not particularly limited, and examples thereof include a light emitting function, a rectifying function, and a power control function.
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, the light emitting device is manufactured by providing a light emitting functional layer on a group 13 element nitride crystal layer. However, a light emitting device is produced by 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, and an n-type layer. May be good.

FIG. 8 schematically shows the layer structure of the light emitting device according to one aspect of the present invention. The light emitting element 21 shown in FIG. 8 includes a self-standing substrate 13 and a light emitting functional layer 18 formed on the substrate. The light emitting functional layer 18 brings about 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 bring about 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 or red, or may emit ultraviolet light without or together with visible light. The light emitting functional layer 18 preferably constitutes at least a part of a light emitting element using a pn junction, and the pn junction forms the p-type layer 18a and the n-type layer 18c as shown in FIG. The active layer 18b may be included between the two. At this time, a double heterojunction or a single heterojunction (hereinafter collectively referred to as a heterojunction) using a layer having a bandgap smaller than that of the p-type layer and / or the n-type layer as the active layer may be used. Further, as one form of the p-type layer-active layer-n-type layer, a quantum well structure in which the thickness of the active layer is thinned can be adopted. Needless to say, in order to obtain a quantum well, a double heterojunction 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 adopted. Further, a multiple quantum well structure (MQW) in which a large number of these quantum well structures are stacked may be used. By adopting these structures, the luminous efficiency can be improved as compared with the pn junction. As described above, the light emitting functional layer 18 preferably includes a pn junction and / or a hetero junction and / or a quantum well junction having a light emitting function. In addition, 20 and 22 are examples of electrodes.

Therefore, at least one or more layers constituting the light emitting functional layer 18 are 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 include one or more. The n-type layer, the p-type layer and the active layer (if any) may be composed of materials having the same main component or materials having different main components from each other.

The material of each layer constituting the light emitting functional layer 18 is not particularly limited as long as it grows roughly according to the crystal orientation of the group 13 element nitride crystal layer and has a light emitting function, but is a gallium nitride (GaN) -based material. It is preferable that the material is composed of at least one main component selected from zinc oxide (ZnO) -based material and aluminum nitride (AlN) -based material, and a dopant for controlling the p-type to n-type is appropriately used. It may include. A particularly preferable material is a gallium nitride (GaN) -based material. Further, the material constituting the light emitting functional layer 18 may be a mixed crystal in which AlN, InN or the like is dissolved in GaN in order to control the band gap thereof. Further, as described in the preceding paragraph, the light emitting functional layer 18 may be a heterojunction composed of a plurality of types 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, zinc oxide (ZnO) -based material may be used for the p-type layer, and 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 method for forming the light emitting functional layer 18 and the buffer layer is not particularly limited as long as it grows in accordance with the crystal orientation of the group 13 element nitride crystal layer, but is a vapor phase method such as MOCVD, MBE, HVPE, and sputtering. , Na flux method, amonothermal method, hydrothermal method, liquid phase method such as solgel method, powder method utilizing solid phase growth of powder, and combinations thereof are preferably exemplified.

(Example 1)
(Preparation of gallium nitride self-supporting substrate)
A 0.3 μm alumina film 2 is formed on a sapphire substrate 1 having a diameter of φ6 inch by a sputtering method, and then a seed crystal film 3 made of gallium nitride having a thickness of 2 μm is formed by a MOCVD method to form a seed crystal substrate. Obtained.

This seed crystal substrate was placed in an alumina crucible in a glove box with a nitrogen atmosphere. Next, metallic gallium and metallic sodium were filled in the crucible so that Ga / Ga + Na (mol%) = 15 mol%, and the crucible was covered with an alumina plate. The crucible was placed in a stainless steel inner container, then placed in a stainless steel outer container that could hold it, and closed with a container lid with a nitrogen introduction pipe. This outer container was placed on a turntable installed in a heating section in a crystal manufacturing apparatus that had been vacuum-baked in advance, and the pressure-resistant container was covered and sealed.

Next, the inside of the pressure-resistant container was evacuated to 0.1 Pa or less with a vacuum pump. Then, while adjusting the upper heater, middle heater and lower heater to heat the temperature of the heating space to 870 ° C, nitrogen gas is introduced from the nitrogen gas cylinder up to 4.0 MPa, and the outer container is placed around the central axis. It was rotated clockwise and counterclockwise at a constant cycle at a speed of 20 rpm. Acceleration time = 12 seconds, holding time = 600 seconds, deceleration time = 12 seconds, stop time = 0.5 seconds. Then, it was held in this state for 40 hours. Then, after naturally cooling to room temperature and reducing the pressure to atmospheric pressure, the lid of the pressure-resistant container was opened and the crucible was taken out from the inside. The solidified metallic sodium in the crucible was removed, and a crack-free gallium nitride free-standing substrate peeled off from the seed crystal substrate was recovered.

(Evaluation)
When the upper surface 13a of the gallium nitride self-supporting substrate 13 having the gallium nitride surface polished is observed CL with a scanning electron microscope (SEM) equipped with a cathodoluminescence (CL) detector, the high-intensity light emitting unit 5 as shown in FIGS. And the low-intensity light emitting region 6 was confirmed.

Further, the upper surface of the gallium nitride self-supporting substrate was observed with a scanning electron microscope (SEM) equipped with a cathodoluminescence (CL) detector by polishing the cut surface. As a result, as shown in FIG. 3, in the CL image, a high-intensity light emitting portion that emits 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 had grown without voids.

Further, the gallium nitride free-standing substrate was cut into a cross section perpendicular to the upper surface thereof, and the cut surface was polished and observed with a scanning electron microscope (SEM) equipped with a cathodoluminescence (CL) detector. As a result, as shown in FIG. 6, in the CL image, a high-intensity light emitting portion that emits 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), voids and the like were not confirmed, and it was confirmed that homogeneous gallium nitride crystals were growing. That is, even on the upper surface of the Group 13 element nitride crystal layer, a high-intensity light-emitting part is present in CL observation as in the cross section, but in SEM, it has the same shape as the high-intensity light-emitting part seen in the CL image in the same field of view. Or a similar microstructure did not exist.

(Measurement of dislocation density)
Then, the dislocation density was measured on the upper surface of the Group 13 element nitride crystal layer. The dislocation density was calculated by observing CL and measuring the density of dark spots, which are dislocation sites. As a result of observing 5 fields of 80 μm × 105 μm, the variation was in the range of 1.2 × 10 ⁴ / cm ^{2 to} 9.4 × 10 ⁴ / cm ² , and the average was 3.3 × 10 ⁴ / cm ² .

(Measurement of surface tilt angle)
As a result of measuring the half width of the (0002) plane reflection of the X-ray locking curve on the upper surface of the gallium nitride crystal layer, it was 73 seconds.

(Measurement of surface twist angle)
The half width of the (1000) plane reflection of the X-ray locking curve on the upper surface of the gallium nitride crystal layer was measured and found to be 85 seconds.

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

(Formation of light emitting functional layer by MOCVD method)
Using the MOCVD method, 1 μm of an n-GaN layer doped so that the Si atom concentration was 5 × 10 ¹⁸ / cm ³ was deposited as an n-type layer on the upper surface of the gallium nitride self-supporting substrate at 1050 ° C. Next, a multiple quantum well layer was deposited as a light emitting layer at 750 ° C. Specifically, five 2.5 nm well layers made of InGaN and six 10 nm barrier layers made of GaN were alternately laminated. Next, as a p-type layer, 200 nm of p-GaN doped so that the Mg atom concentration was 1 × 10 ¹⁹ / cm ³ was deposited at 950 ° C. Then, it was taken out from the MOCVD apparatus and heat-treated at 800 ° C. for 10 minutes in a nitrogen atmosphere as a treatment for activating Mg ions in the p-type layer.
No pits were observed on the surface of the obtained light emitting functional layer.

(Manufacturing of light emitting element)
Using a photolithography process and a vacuum vapor deposition method, Ti / Al / Ni / Au films as cathode electrodes were placed on the surfaces of the gallium nitride self-supporting substrate opposite to the n-GaN layer and the p-GaN layer at 15 nm and 70 nm, respectively. , 12 nm and 60 nm were patterned. Then, in order to improve the ohm-like contact characteristics, a heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds. Further, a photolithography process and a vacuum vapor deposition method were used to pattern a Ni / Au film as a translucent anode electrode on the p-type layer to a thickness of 6 nm and 12 nm, respectively. Then, in order to improve the ohm-like contact characteristics, a heat treatment at 500 ° C. was performed for 30 seconds in a nitrogen atmosphere. Furthermore, using a photolithography process and a vacuum vapor deposition method, the Ni / Au film used as the anode electrode pad has a thickness of 5 nm and 60 nm, respectively, in a part of the upper surface of the Ni / Au film used as the translucent anode electrode. Patterned. The substrate thus obtained was cut into chips and further mounted on a lead frame to obtain a light emitting element having a vertical structure.

(Evaluation of light emitting element)
When 100 individuals arbitrarily selected from the produced elements were energized between the cathode electrode and the anode electrode and IV measurement was performed, rectification was confirmed for 90 of them. Further, when a forward current was applied, light emission with a wavelength of 460 nm was confirmed.

(Adjustment of arithmetic average roughness Ra on the upper surface and film formation of light emitting functional layer)
The upper surface of the obtained self-supporting 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 by RIE, and the upper surface with Ra of 1.0 nm is adjusted by mechanical polishing. did.
Next, a light emitting functional layer was epitaxially grown on the upper surface of each self-supporting substrate by the MOCVD method as described above. As a result, no surface pits were observed in any of the cases.

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

(Formation of rectifying function layer by MOCVD method)
Using the MOCVD (organometallic chemical vapor deposition) method, an n-GaN layer doped as an n-type layer at 1050 ° C. so that the Si atom concentration becomes 1 × 10 ¹⁶ / cm ³ is formed into a 5 μm layer. Filmed.

Using a photolithography process and a vacuum vapor deposition method, Ti / Al / Ni / Au films as ohmic electrodes were placed on the surface of the self-supporting substrate opposite to the n-GaN layer at thicknesses of 15 nm, 70 nm, 12 nm, and 60 nm, respectively. Patterned. Then, in order to improve the ohm-like contact characteristics, a heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds. Further, using a photolithography process and a vacuum vapor deposition method, Ni / Au films were patterned as shotkey electrodes on the n-GaN layer formed by the MOCVD method with thicknesses of 6 nm and 80 nm, respectively. The substrate thus obtained was cut into chips and further mounted on a lead frame to obtain a rectifying element.

(Evaluation of rectifying element)
When the IV measurement was performed, the rectification characteristics were confirmed.

(Creation of power control element)
A functional element having a power control function was manufactured.
A self-supporting substrate was produced in the same manner as in the above examples. However, unlike Example 1, when the gallium nitride crystal was formed by the Na flux method, impurities were not doped. An Al _0.25 Ga _0.75 N / GaN HEMT structure was formed on the upper surface of the self-supporting substrate thus obtained by the MOCVD method as follows, electrodes were formed, and transistor characteristics were confirmed.

Using the MOCVD (organometallic chemical vapor deposition) method, a 3 μm film of a GaN layer without impurity doping was formed as an i-type layer at 1050 ° C. on a self-supporting substrate. Next, an Al _0.25 Ga _0.75 N layer was formed into a 25 nm film at the same 1050 ° C. as a functional layer. As a result, an Al _0.25 Ga _0.75 N / GaN HEMT structure was obtained.

Using a photolithography process and a vacuum vapor deposition method, Ti / Al / Ni / Au films as source and drain electrodes were patterned with thicknesses of 15 nm, 70 nm, 12 nm and 60 nm, respectively. Then, in order to improve the ohm-like contact characteristics, a heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds. Further, using a photolithography process and a vacuum vapor deposition method, Ni / Au films as gate electrodes were formed by Schottky junction with thicknesses of 6 nm and 80 nm, respectively, and patterned. The substrate thus obtained was cut into chips and further mounted on a lead frame to obtain a power control element.

(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 this example is the N-plane, but the same effect can be obtained on the Ga-plane.

Further, in a preferred embodiment, the half width of the (1000) plane reflection of the X-ray locking curve on the upper surface of the Group 13 element nitride crystal layer is 10,000 seconds or less and 20 seconds or more. This indicates that both the surface tilt angle and the surface twist angle on the upper surface are small, and the crystal orientation as a whole is more highly oriented like a single crystal. With such a microstructure in which the crystal orientation on the surface is more highly oriented as a whole, 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 on the microstructure can be reduced. Can be uniformly aligned, and the yield of functional elements is also improved.

Claims (27)

A group 13 element nitride crystal layer composed of a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof, and having a top surface and a bottom surface.
When the upper surface is observed by cathodoluminescence, it has a high-intensity light emitting portion and a low-intensity light emitting region adjacent to the high-intensity light emitting portion.
The half width of the (0002) plane reflection of the X-ray locking curve on the upper surface is 3000 seconds or less and 20 seconds or more.
A group 13 element nitride layer, characterized in that the arithmetic average roughness Ra of the upper surface is 0.05 nm or more and 1.0 nm or less. 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 the 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 nitride according to claim 3, wherein the dislocation density on the upper 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. Material crystal layer. Any of claims 1 to 4, wherein the high-intensity light emitting unit forms a continuous phase, and the low-intensity light emitting region forms a discontinuous phase partitioned by the high-intensity light emitting unit. The group 13 element nitride crystal layer according to one claim. The group 13 element nitride according to any one of claims 1 to 5, wherein the high-intensity light emitting portion includes a portion extending along the m-plane of the group 13 element nitride crystal. Material crystal layer. The Group 13 element according to any one of claims 1 to 6, wherein the half width of the (1000) plane reflection of the X-ray locking 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 self-supporting substrate comprising the Group 13 elemental nitride layer according to any one of claims 1 to 8. A functional element comprising the self-supporting substrate according to claim 9 and a functional layer provided on the group 13 element nitride layer. The functional element 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 a Group 13 element nitride layer according to any one of claims 1 to 8 provided on the support substrate. A functional element having the composite substrate according to claim 12 and a functional layer provided on the group 13 element nitride layer. 13. The functional element according to claim 13, wherein the function of the functional layer is a light emitting function, a rectifying function, or a power control function. A group 13 element nitride crystal layer composed of a group 13 element nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof, and having a top surface and a bottom surface.
When the upper surface is observed by cathodoluminescence, it has a high-intensity light emitting portion and a low-intensity light emitting region adjacent to the high-intensity light emitting portion.
The half width of the (1000) surface reflection of the X-ray locking curve on the upper surface is 10,000 seconds or less and 20 seconds or more.
A group 13 element nitride layer, characterized in that the arithmetic average roughness Ra of the upper surface is 0.05 nm or more and 1.0 nm or less. 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 the 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 nitride according to claim 17, wherein the dislocation density on the upper 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. Material crystal layer. Any of claims 15 to 18, wherein the high-intensity light emitting unit forms a continuous phase, and the low-intensity light emitting region forms a discontinuous phase partitioned by the high-intensity light emitting unit. The group 13 element nitride crystal layer according to one claim. The group 13 element nitride according to any one of claims 15 to 19, wherein the high-intensity light emitting portion includes a portion extending along the m-plane of the group 13 element nitride crystal. Material 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 self-supporting 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. 23. The functional element 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 a Group 13 element nitride layer according to any one of claims 15 to 21 provided on the support substrate. A functional element having the composite substrate according to claim 25 and a functional layer provided on the group 13 element nitride layer. The functional element according to claim 26, wherein the function of the functional layer is a light emitting function, a rectifying function, or a power control function.

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