CN115116828B - Homoepitaxial structure based on nitride single crystal substrate and uniformity regulating and controlling method thereof - Google Patents

Abstract

The application discloses a homoepitaxial structure based on a nitride single crystal substrate and a uniformity regulating and controlling method thereof. The uniformity control method comprises the following steps: providing a nitride single crystal substrate containing a second group III element; growing an interfacial relaxation layer on the substrate, the interfacial relaxation layer comprising a binary nitride layer comprising a first group III element, the first group III element being different from the second group III element to create a compressive or tensile stress to balance warpage of the substrate; and growing a warp-controlling layer on the interface relaxation layer, wherein the warp-controlling layer comprises a ternary nitride layer or a superlattice structure containing the ternary nitride layer. The application realizes the controllable warp and high uniformity growth of the homoepitaxial structure by the controllable growth of the interfacial relaxation layer and the warp regulating layer on the substrate; meanwhile, the prepared homoepitaxial structure is smoother, and has wide application prospect in photoelectric devices or electronic devices.

Description

Homoepitaxial structure based on nitride single crystal substrate and its uniformity control method

Technical Field

The present application relates to a semiconductor light-emitting structure, specifically to a homoepitaxial structure based on a nitride single crystal substrate and a method for regulating its uniformity, and belongs to the field of semiconductor technology.

Background technique

The growth of GaN-based devices is mostly based on heterogeneous substrates such as sapphire and silicon. It is necessary to eliminate the mismatch from the substrate by growing a transition layer to obtain a GaN epitaxial layer. At the same time, its transition layer is also an important means to adjust the unevenness of the epitaxial wafer, thereby adjusting the uniformity of the epitaxial wafer growth. For example, in the epitaxial growth of blue light LEDs, when growing the quantum wells in the active area, the In component determines the emission wavelength, and the incorporation of In is related to temperature. If the epitaxial wafer is uneven, the temperature will be uneven, resulting in uneven distribution of In, thereby reducing the uniformity of the wavelength. At this time, the warping can usually be adjusted by adjusting the transition layer, so that the epitaxial wafer is as flat as possible during the quantum well growth process, thereby ensuring wavelength uniformity.

Homoepitaxial growth based on GaN single crystal substrates does not require any transition layer because the substrate is already a GaN material layer. Therefore, the warpage value cannot be adjusted through the transition layer in the later growth. The warpage changes of epitaxial layer materials with different doping concentrations and the GaN single crystal substrate itself at high temperatures will affect the temperature of the epitaxial wafer during growth, and thus affect the uniformity of the epitaxial wafer. However, the current conventional growth methods do not have any technology or method to regulate this.

Summary of the invention

The main purpose of the present application is to provide a homoepitaxial structure based on a nitride single crystal substrate and a method for controlling its uniformity, so as to overcome the deficiencies in the prior art.

In order to achieve the aforementioned invention objectives, the technical solutions adopted in this application include:

One aspect of the present application provides a method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate, comprising:

providing a nitride single crystal substrate, the substrate comprising a second Group III element;

Growing an interface relaxation layer on the substrate, the interface relaxation layer comprising a binary nitride layer, the binary nitride layer comprising a first Group III element, the first Group III element being different from the second Group III element to generate compressive stress or tensile stress, thereby balancing the warpage of the substrate;

A warp regulation layer is grown on the interface relaxation layer, the surface of the warp regulation layer is flat, the warp regulation layer comprises a ternary nitride layer or a superlattice structure comprising a ternary nitride layer, and the ternary nitride layer comprises a first group III element and a second group III element.

One aspect of the present application provides a homoepitaxial structure based on a nitride single crystal substrate, characterized in that it includes:

Nitride single crystal substrate,

An interface relaxation layer grown on the substrate, the interface relaxation layer comprising a binary nitride layer, the constituent material of the binary nitride layer being lattice mismatched with the constituent material of the substrate to generate compressive stress or tensile stress, thereby balancing the warping of the substrate;

A warp regulation layer is grown on the interface relaxation layer, the surface of the warp regulation layer is flat, and the warp regulation layer includes a ternary nitride layer or a superlattice structure including the ternary nitride layer.

Another aspect of the present application provides use of the homoepitaxial structure based on a nitride single crystal substrate in preparing a UV-LED device or a GaN-based device.

Compared with the prior art, the present application realizes highly uniform growth of a homoepitaxial structure by first performing controllable growth of an interface relaxation layer and a warp regulation layer on a nitride single crystal substrate (specifically by adjusting the composition and thickness of the interface relaxation layer and the warp regulation layer); at the same time, the prepared homoepitaxial structure is smoother and has broad application prospects in optoelectronic devices or electronic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

FIG. 1a - FIG. 1b are schematic diagrams of a homoepitaxial structure in a typical embodiment of the present application.

FIG2 is a photoluminescence PL test spectrum of the homoepitaxial structure sample A prepared in Example 1 of the present application;

FIG3 is a photoluminescence PL test spectrum of the homoepitaxial structure sample B prepared in Comparative Example 1 of the present application;

4 is a schematic diagram of a device for introducing a first Group III source, a second Group III source and a nitrogen source when preparing an interface relaxation layer and a warpage regulation layer in a typical embodiment of the present application.

Detailed ways

In view of the deficiencies in the prior art, the inventor of this case, after long-term research and practice, was able to propose the technical solution of this application, which will be described in more detail below.

Some embodiments of the present application provide a method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate, including:

providing a nitride single crystal substrate, the substrate comprising a second Group III element;

Growing an interface relaxation layer on the substrate, the interface relaxation layer comprising a binary nitride layer, the binary nitride layer comprising a first Group III element, the first Group III element being different from the second Group III element to generate compressive stress or tensile stress, thereby balancing the warpage of the substrate;

A warp regulation layer is grown on the interface relaxation layer, the surface of the warp regulation layer is flat, the warp regulation layer comprises a ternary nitride layer or a superlattice structure comprising a ternary nitride layer, and the ternary nitride layer comprises a first group III element and a second group III element.

In one embodiment, the lattice constant of the constituent material of the binary nitride layer is greater than the lattice constant of the constituent material of the nitride single crystal substrate to generate tensile stress; or, the lattice constant of the constituent material of the binary nitride layer is less than the lattice constant of the constituent material of the nitride single crystal substrate to generate compressive stress.

In one embodiment, the first Group III element is Al or In, and the second Group III element is Ga.

In one embodiment, the first Group III element is adjacent to the second Group III element.

In one embodiment, the thickness of the nitride single crystal substrate is greater than 1 μm.

Furthermore, the thickness of the nitride single crystal substrate is 1-2.5 μm.

In one embodiment, the thickness of the interface relaxation layer is 1-10 nm.

In one embodiment, the thickness of the ternary nitride layer is 10 nm-100 nm, and the thickness of the superlattice structure including the ternary nitride layer is 10 nm-200 nm.

In one embodiment, when the preset stress is tensile stress, the content of the first group III element in the binary nitride layer is 5 at.% to 10 at.%, and the content of the first group III element in the superlattice structure including the ternary nitride layer is 5 at.% to 20 at.%.

Specifically, when the binary nitride layer is InN material, the ternary nitride layer is InGaN material, and the content of In element in the InGaN material is 5at.% to 10at.%, the thickness of the ternary nitride layer is 10 to 50nm, and the components in the ternary nitride layer can be constant or gradually changed.

Specifically, when the binary nitride layer is InN material, the superlattice structure including the ternary nitride layer is an InGaN/GaN superlattice structure, and the content of In element in the InGaN material is 5at.% to 20at.%, and the thickness of the superlattice structure including the ternary nitride layer is 10 to 200nm.

In one embodiment, when the preset stress is compressive stress, the content of the first group III element in the ternary nitride layer is 5 at.% to 20 at.%, and the content of the first group III element in the superlattice structure including the ternary nitride layer is 5 at.% to 100 at.%.

Specifically, when the binary nitride layer is AlN material, the ternary nitride layer is AlGaN single layer material, the Al content in AlGaN is 5at.% to 20at.%, the thickness of the ternary nitride layer is 10 to 100nm, and the components in the ternary nitride layer can be constant or gradually changed.

Specifically, when the binary nitride layer is AlN material, the superlattice structure including the ternary nitride layer is an AlGaN/GaN superlattice structure, the content of Al element in AlGaN is 5at.% to 100at.%, and the thickness of the superlattice structure including the ternary nitride layer is 10 to 200nm.

Furthermore, the superlattice structure includes an InGaN/GaN superlattice structure, an AlGaN/GaN superlattice structure, etc., but is not limited thereto.

In the present application, the lattice constant of GaN is between InN and AlN, and the thermal mismatch of the three is smaller than the lattice mismatch, so the transition between tensile stress and compressive stress can be flexibly realized. For example, the lattice constant of InN is greater than that of GaN. At this time, when In(Ga)N is grown on a GaN single crystal substrate, tensile stress will be introduced, causing the subsequently grown epitaxial layer to bend in a concave direction. The lattice constant of AlN is smaller than that of GaN. At this time, when Al(Ga)N is grown on a substrate, compressive stress will be introduced, causing the subsequently grown epitaxial layer to bend in a convex direction. However, since a heterogeneous layer material is grown, its lattice is not matched, and a single crystal substrate with very good crystal quality is required as a substrate. Thereby realizing the uniformity control method of the homoepitaxial structure of a nitride single crystal substrate in the present application.

In one embodiment, the method for controlling the uniformity of the homoepitaxial structure based on a nitride single crystal substrate specifically includes:

S1, placing the substrate into a growth chamber, and forming a protective atmosphere in the growth chamber, then setting the substrate temperature to the growth temperature of the binary nitride layer, and then inputting a first group III source into the growth chamber to deposit a layer of atoms of the first group III element on the surface of the substrate to form an interface wetting layer;

S2, inputting a first Group III source and a nitrogen source into the growth chamber to grow a binary nitride layer on the interface wetting layer, thereby forming an interface relaxation layer;

S3. Inputting a first Group III source, a second Group III source and a nitrogen source into the growth chamber, growing a ternary nitride layer or a superlattice structure including the ternary nitride layer on the interface relaxation layer, thereby forming a warp regulation layer.

Furthermore, the first Group III source may be an In, Al, Ga, B source, etc., but is not limited thereto.

Specifically, the first Group III source may be TMIn or TMAl.

Further, the second Group III source may be Al, Ga, source, etc., but is not limited thereto.

In one embodiment, the nitride single crystal substrate includes a GaN single crystal substrate or an AlN single crystal substrate.

In one embodiment, step S3 specifically includes: alternately inputting the first group III source, the second group III source and the nitrogen source into the growth chamber, growing a superlattice structure on the interface relaxation layer, thereby forming the warp regulation layer.

In one embodiment, step S3 specifically includes: inputting a first Group III source, a second Group III source and a nitrogen source into the growth chamber, and controlling the flow rates of the first Group III source, the second Group III source and the nitrogen source to be below 200 sccm, and setting the gas pressure in the growth chamber to 30-70 torr, growing a superlattice structure on the interface relaxation layer, thereby forming the warp regulation layer.

For example, for the AlGaN/GaN superlattice layer, the required Al source, Ga source and N source can be alternately introduced to alternately deposit films on the substrate surface to reduce the growth rate and improve the density of the lattice arrangement; in addition, when growing the AlGaN/GaN superlattice layer, the gas flow rate can be reduced to 200sccm and the pressure can be reduced to 30-70torr to improve the density of the lattice arrangement.

In one embodiment, when preparing the interface relaxation layer and the warpage regulation layer, the schematic diagram of the first Group III source, the second Group III source and the nitrogen source introduction device is shown in FIG4 .

In one embodiment, when the nitride single crystal substrate is a GaN single crystal substrate, the binary nitride layer is an AlN layer, the ternary nitride layer is an _{AlxGa1 -xN} layer, the superlattice structure including the ternary nitride layer is an _{AlxGa1 -xN} /GaN superlattice structure, 0＜x＜1;

Alternatively, when the nitride single crystal substrate is a GaN single crystal substrate, the binary nitride layer is an InN layer, the ternary nitride layer is an In _y Ga _1-y N layer, the superlattice structure including the ternary nitride layer is an In _y Ga _1-y N/GaN superlattice structure, 0＜y＜1;

Alternatively, when the nitride single crystal substrate is an AlN single crystal substrate, the binary nitride layer is a GaN layer, the ternary nitride layer is an _{AlxGa1 -xN} layer, the superlattice structure including the ternary nitride layer is an _{AlxGa1 -xN} /AlN superlattice structure, 0＜x＜1;

Alternatively, when the nitride single crystal substrate is an AlN single crystal substrate, the binary nitride layer is a BN layer, the ternary nitride layer is a _{BxAl1 -xN} layer, the superlattice structure including the ternary nitride layer is a _BxAl1-xN /AlN superlattice structure, and 0＜x＜1.

In one embodiment, the uniformity control method further comprises: growing a semiconductor functional layer on the warp control layer.

In a more specific embodiment, the method for controlling the uniformity of the homoepitaxial structure based on a nitride single crystal substrate may include:

First, under the protection of ammonia, the temperature of the GaN single crystal substrate is raised to the growth temperature of the InN-based or AlN-based material, and then the interface relaxation layer is grown. It is necessary to disconnect the ammonia and introduce the organic metal source TMIn or TMAl at the same time, and the time is controlled to be a few seconds. The purpose is to lay a layer of metal In atoms or metal Al atoms on the GaN single crystal substrate, which serves to wet the interface layer of the secondary epitaxial growth of the substrate. Then cut in the ammonia to grow InN or AlN materials, and perform lattice relaxation for subsequent mismatch materials, so as to grow an interface relaxation layer with a thickness controlled at 1-10nm. The interface relaxation layer performs early relaxation and interface treatment for the growth of the warp control layer to ensure the crystal quality and effective regulation of subsequent thicker materials.

Next, corresponding to the interface relaxation layer of the InN-based material, the warpage control layer is grown as InGaN material or InGaN/GaN superlattice structure to adjust the curvature of the epitaxial wafer in the concave direction; the content of the In element in the InGaN material is 5% to 10%, the composition can be unchanged or the composition can be gradually changed, and the thickness range is 10-50nm. If it is an InGaN/GaN superlattice structure, the content of the In element in InGaN is 5% to 20%, and the thickness range is 10-200nm. Corresponding to the interface relaxation layer of the AlN-based material, the warpage control layer is grown as AlGaN single layer material or AlGaN superlattice structure to adjust the curvature of the epitaxial wafer in the convex direction; the content of the Al element in the AlGaN material is 5% to 20%, the composition can be unchanged or the composition can be gradually changed, and the thickness range is 10-100nm. If it is an AlGaN/GaN superlattice structure, the content of the Al element in AlGaN is 5% to 100%, and the thickness range is 10-200nm. The above completes the growth of the warpage control layer.

The present application proposes to first deposit an interface relaxation layer on a GaN single crystal substrate to prepare for a subsequent warpage control layer, wherein the material of the layer is a metal In/InN material or a metal Al/AlN material, and then an Al(In)GaN material or a superlattice material is used as a warpage control layer, and then an epitaxial structure is grown, such as an LED of an optoelectronic device or a HEMT structure of an electronic device. The present application adjusts the concavity and convexity of the entire epitaxial wafer by adjusting the composition and thickness of In(Ga)N or Al(Ga)N in the warpage control layer, thereby achieving controllable warpage and growth of highly uniform epitaxial wafers.

In order to balance the warping problem of the nitride single crystal substrate in the present application, an interface relaxation layer with a large lattice mismatch with the nitride single crystal substrate is first grown to balance the warping of the substrate. It can also serve as a transition layer for the subsequent warping control layer to improve the crystal quality. Secondly, the subsequently grown warping control layer is to gradually flatten the structure after the balanced warping. The growth rate can be slowed down to make the lattice arrangement denser, the tensile stress or compressive stress more uniform, and better flatness can be achieved.

Some embodiments of the present application provide a homoepitaxial structure based on a nitride single crystal substrate, comprising:

Nitride single crystal substrate;

An interface relaxation layer grown on the substrate, the interface relaxation layer comprising a binary nitride layer, the constituent material of the binary nitride layer being lattice mismatched with the constituent material of the substrate to generate compressive stress or tensile stress, thereby balancing the warping of the substrate;

A warp regulation layer is grown on the interface relaxation layer, the surface of the warp regulation layer is flat, and the warp regulation layer includes a ternary nitride layer or a superlattice structure including the ternary nitride layer.

In one embodiment, the homoepitaxial structure based on a nitride single crystal substrate further includes a semiconductor functional layer, and the semiconductor functional layer is grown on the warp regulating layer.

In one embodiment, the lattice constant of the constituent material of the first Group III nitride layer of the binary nitride layer is greater than the lattice constant of the constituent material of the substrate to generate tensile stress; or, the lattice constant of the constituent material of the first Group III nitride layer is less than the lattice constant of the constituent material of the substrate to generate compressive stress.

In one embodiment, the thickness of the nitride single crystal substrate is greater than 1 μm.

Furthermore, the thickness of the nitride single crystal substrate is 1-2.5 μm.

In one embodiment, the thickness of the interface relaxation layer is 1-10 nm.

In one embodiment, the thickness of the ternary nitride layer is 10 nm-100 nm, and the thickness of the superlattice structure composed of the ternary nitride layer is 10 nm-200 nm.

In one embodiment, when the nitride single crystal substrate is a GaN single crystal substrate, the binary nitride layer is an AlN layer, the ternary nitride layer is an _{AlxGa1 -xN} layer, the superlattice structure including the ternary nitride layer is an _{AlxGa1 -xN} /GaN superlattice structure, 0＜x＜1;

Alternatively, when the nitride single crystal substrate is a GaN single crystal substrate, the binary nitride layer is an InN layer, the ternary nitride layer is an In _y Ga _1-y N layer, the superlattice structure including the ternary nitride layer is an In _y Ga _1-y N/GaN superlattice structure, 0＜y＜1;

Alternatively, when the nitride single crystal substrate is an AlN single crystal substrate, the binary nitride layer is a GaN layer, the ternary nitride layer is an _{AlxGa1 -xN} layer, the superlattice structure including the ternary nitride layer is an _{AlxGa1 -xN} /AlN superlattice structure, 0＜x＜1;

Alternatively, when the nitride single crystal substrate is an AlN single crystal substrate, the binary nitride layer is a BN layer, the ternary nitride layer is a _{BxAl1 -xN} layer, the superlattice structure including the ternary nitride layer is a _{BxAl1 -xN} /AlN superlattice structure, and 0<x<1.

In one embodiment, the uniformity control method further comprises: growing a semiconductor functional layer on the warp control layer.

In one embodiment, when the preset stress is tensile stress, the content of the first group III element in the binary nitride layer is 5 at.% to 10 at.%, and the content of the first group III element in the superlattice structure including the ternary nitride layer is 5 at.% to 20 at.%.

Specifically, when the binary nitride layer is InN material, the ternary nitride layer is InGaN material, and the content of In element in the InGaN material is 5at.% to 10at.%, the thickness of the ternary nitride layer is 10 to 50nm, and the components in the ternary nitride layer can be constant or gradually changed.

Specifically, when the binary nitride layer is InN material, the superlattice structure including the ternary nitride layer is an InGaN/GaN superlattice structure, and the content of In element in the InGaN material is 5at.% to 20at.%, and the thickness of the superlattice structure including the ternary nitride layer is 10 to 200nm.

In one embodiment, when the preset stress is compressive stress, the content of the first group III element in the ternary nitride layer is 5 at.% to 20 at.%, and the content of the first group III element in the superlattice structure including the ternary nitride layer is 5 at.% to 100 at.%.

Specifically, when the binary nitride layer is AlN material, the ternary nitride layer is AlGaN single layer material, the Al content in AlGaN is 5at.% to 20at.%, the thickness of the ternary nitride layer is 10 to 100nm, and the components in the ternary nitride layer can be constant or gradually changed.

Specifically, when the binary nitride layer is AlN material, the superlattice structure including the ternary nitride layer is an AlGaN/GaN superlattice structure, the content of Al element in AlGaN is 5at.% to 100at.%, and the thickness of the superlattice structure including the ternary nitride layer is 10 to 200nm.

In one embodiment, the nitride single crystal substrate includes a GaN single crystal substrate or an AlN single crystal substrate, but is not limited thereto.

In one embodiment, the homoepitaxial structure is a semiconductor light-emitting device structure, wherein the semiconductor functional layer comprises a semiconductor layer of a first conductivity type, a multi-quantum well light-emitting layer and a semiconductor layer of a second conductivity type.

In one embodiment, the homoepitaxial structure is an electronic device structure, wherein the semiconductor functional layer includes a high resistance layer, an insertion layer, a channel layer, a barrier layer, a cap layer, and the like.

In a more specific embodiment, a homoepitaxial structure based on a nitride single crystal substrate is shown in Figure 1a, comprising a GaN single crystal substrate (the aforementioned nitride semiconductor single crystal substrate), an interface relaxation layer and a warpage regulation layer sequentially grown on the substrate, and an N-type GaN regional layer, an MQWs light-emitting layer, and a p-type GaN regional layer (the aforementioned semiconductor functional layer) formed on the warpage regulation layer. The uniformity of the N-type GaN regional layer, the MQWs light-emitting layer, and the p-type GaN regional layer is regulated by the interface relaxation layer and the warpage regulation layer.

In a more specific embodiment, a homoepitaxial structure based on a nitride single crystal substrate is shown in Figure 1b, including a GaN single crystal substrate (the aforementioned nitride semiconductor single crystal substrate), an interface relaxation layer and a warp regulation layer sequentially grown on the substrate, and a high resistance layer, an insertion layer, a channel layer, a barrier layer, and a cap layer (the aforementioned semiconductor functional layer) formed on the warp regulation layer.

The technical solution of the present application will be described in more detail below in conjunction with the accompanying drawings and several embodiments, but it should be understood that the following embodiments are only for the purpose of explaining and illustrating the technical solution, but do not limit the scope of the present application. In addition, unless otherwise specified, the various raw materials, reaction equipment, detection equipment and methods used in the following embodiments are all known in the art.

Conventional GaN single crystal substrates are prone to concavity during homoepitaxial growth. Therefore, the embodiment takes the uniformity control method adopted to solve the concavity phenomenon of the GaN single crystal substrate as an example.

Example 1

The GaN single crystal substrate was placed in a MOCVD epitaxial system to grow a GaN homogeneous LED epitaxial wafer, which was recorded as sample A.

First, the pressure is set to 70torr, ammonia is turned on, and the temperature is raised to 1100°C in an atmosphere of _N2 carrier gas. After reaching equilibrium, the ammonia is turned off and the TMAl flow rate is cut in at 300sccm for 5s, so that a layer of metal Al atoms is laid on the surface of the single crystal substrate. Then the ammonia is turned on again, and AlN is grown for about 1min with a thickness of about 2nm. The growth of the interface relaxation layer is completed. Then, under the same conditions, Al source, Ga source and nitrogen source are introduced at the same time to grow AlGaN/GaN superlattice materials, where the thickness of AlGaN is 3nm, the content of Al element in AlGaN is 50%, the thickness of GaN is 2nm, and there are 30 periods.

After the warp control layer is completed, the LED epitaxial structure is grown, with 2μm thick n-type GaN, followed by 5 periods of InGaN/GaN quantum wells, where the InGaN has an In element content of 15% and a thickness of 3nm, the GaN has a thickness of 12nm, and then a p-type GaN with a thickness of 200nm.

Comparative Example 1

The method is the same as Example 1, except that: the GaN single crystal substrate does not grow an interface relaxation layer and a warp regulation layer, and the prepared homogeneous GaN epitaxial wafer is recorded as sample B.

Samples A and B in Example 1 and Comparative Example 1 were tested, and Figures 2-3 are the photoluminescence PL test spectra of Sample A and Sample B. It can be seen that the conventional growth method (i.e., the scheme in Comparative Example 1) is prone to lattice bending due to the growth process and subsequent cutting, grinding and polishing of the GaN single crystal substrate, and when growing LEDs, it is easy to have a situation such as sample B with a short wavelength in the middle and a concave center as a whole. In the case of a main wavelength of 450nm, the wavelength uniformity is 4.4nm. After inserting the interface relaxation layer and the warping control layer in Example 1 of the present application, the wavelength uniformity of GaN homogeneous epitaxial wafer sample A is improved to 1.2nm under the same main wavelength. This is the result of the bending of the epitaxial wafer becoming convex, which verifies the effectiveness of the control method provided in the present application.

Comparative Example 2

The method is the same as Example 1, except that: the GaN single crystal substrate does not grow an interface relaxation layer (ie, the AlGaN/GaN superlattice material and the LED epitaxial structure are grown directly on the GaN single crystal substrate in sequence), and the prepared homogeneous GaN epitaxial wafer is recorded as sample C.

Comparative Example 3

The method is the same as Example 1, except that: the warpage regulation layer is not grown on the GaN single crystal substrate (ie, the interface relaxation layer and the LED epitaxial structure are grown sequentially directly on the GaN single crystal substrate), and the prepared homogeneous GaN epitaxial wafer is recorded as sample D.

Example 2

The method is the same as that in Example 1, except that when the warp control layer is grown, the Al source, Ga source and nitrogen source are alternately input into the growth chamber to grow an AlGaN/GaN superlattice structure on the AlN interface relaxation layer, thereby forming the warp control layer.

Specifically, the flow rates of the Al source, Ga source and nitrogen source are controlled to be lower than 200 sccm, and the gas pressure in the growth chamber is set to 30-70 torr, and an AlGaN/GaN superlattice structure is grown on the AlN interface relaxation layer, thereby forming a warp regulation layer.

The prepared homogeneous GaN epitaxial wafer is recorded as sample E.

Example 3

The GaN single crystal substrate is placed in a MOCVD epitaxial system to grow a GaN homogeneous LED epitaxial wafer, which is recorded as sample F.

First, the pressure is set to 50torr, ammonia is turned on, and the temperature is raised to 1100℃ in an atmosphere of _N2 carrier gas. After reaching equilibrium, the ammonia is turned off and the TMAl flow rate is cut in at 300ccm for 5s, and a layer of metal Al atoms is laid on the surface of the single crystal substrate. Then the ammonia is turned on again, and AlN is grown for about 1min with a thickness of about 2nm. The growth of the interface relaxation layer is completed. Then under the same conditions, AlGaN single layer material is grown, where the thickness of AlGaN is 3nm, the content of Al element in AlGaN is 10%, the thickness of GaN is 2nm, and the period is 30. After completing the warp control layer, the LED epitaxial structure is grown, 2μm thick n-type GaN, followed by 5 cycles of InGaN/GaN quantum wells, where the content of InGaN is 15%, the thickness is 3nm, the thickness of GaN is 12nm, and then 200nm thick p-type GaN.

Example 4

The AlN single crystal substrate was placed in a MOCVD epitaxial system to grow an AlN homogeneous UV-LED epitaxial wafer, which was recorded as sample G.

First, the pressure is set to 30torr, ammonia is turned on, and the temperature is raised to 1100°C in an atmosphere of _N2 carrier gas. After reaching equilibrium, the ammonia is turned off and the B source flow rate is cut in at 200ccm for 5 seconds to spread about a layer of B atoms on the surface of the single crystal substrate. Then the ammonia is turned on again, and BN is grown for about 1 minute with a thickness of about 2nm. The growth of the interface relaxation layer is completed. Then, under the same conditions, the superlattice material of BN/AlN is grown, where the thickness of BN is 3nm, the thickness of AlN is 2nm, and the period is 25. After completing the warp control layer, the UV-LED epitaxial structure is grown, 2μm thick n-type AlGaN, followed by 5 cycles of AlGaN/GaN quantum wells, where the Al content of AlGaN is 50%, the thickness is 3nm, the thickness of GaN is 12nm, and then 200nm thick p-type AlGaN.

LED devices were fabricated using the homoepitaxial structures in Examples 1-4 and Comparative Examples 1-3 in a manner known in the art, and then these devices were tested as shown in Table 1.

Table 1 Test results of LED devices made of homoepitaxial structures in Examples 1-4 and Comparative Examples 1-3

Finally, it should be noted that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims (7)

1. A method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate, comprising: S1, placing a nitride single crystal substrate into a growth chamber, and forming a protective atmosphere in the growth chamber, then setting the substrate temperature to the growth temperature of the binary nitride layer, and then inputting a first group III source into the growth chamber to deposit a layer of atoms of the first group III element on the surface of the substrate to form an interface wetting layer; wherein the substrate includes a second group III element; and the thickness of the nitride single crystal substrate is greater than 1 μm; S2, inputting a first group III source and a nitrogen source into the growth chamber, growing a binary nitride layer on the interface wetting layer, thereby forming an interface relaxation layer; the interface relaxation layer comprises a binary nitride layer, the binary nitride layer comprises a first group III element, the first group III element is different from the second group III element, so as to generate compressive stress or tensile stress, thereby balancing the warping of the substrate; the thickness of the interface relaxation layer is 1-10nm; S3, inputting a first group III source, a second group III source and a nitrogen source into the growth chamber, growing a ternary nitride layer or a superlattice structure including the ternary nitride layer on the interface relaxation layer, thereby forming a warp regulation layer; the surface of the warp regulation layer is flat, the warp regulation layer includes a ternary nitride layer or a superlattice structure including the ternary nitride layer, the ternary nitride layer includes a first group III element and a second group III element; the thickness of the ternary nitride layer is 10nm-100nm, and the thickness of the superlattice structure including the ternary nitride layer is 10nm-200nm; S4, growing a semiconductor functional layer on the warpage regulating layer; The nitride single crystal substrate is an AlN single crystal substrate, the binary nitride layer is a BN layer, the ternary nitride layer is a _{BxAl1 -xN} layer, the superlattice structure including the ternary nitride layer is a _{BxAl1 -xN} /AlN superlattice structure, and 0<x<1. 2. The uniformity control method of the homoepitaxial structure based on the nitride single crystal substrate according to claim 1 is characterized in that: the lattice constant of the constituent material of the binary nitride layer is greater than the lattice constant of the constituent material of the nitride single crystal substrate to generate tensile stress; or, the lattice constant of the constituent material of the binary nitride layer is less than the lattice constant of the constituent material of the nitride single crystal substrate to generate compressive stress. 3. The method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate according to claim 1, wherein the thickness of the nitride single crystal substrate is 1-2.5 μm. 4. The uniformity control method of the homoepitaxial structure based on the nitride single crystal substrate according to claim 1 is characterized in that step S3 specifically comprises: alternately inputting the first Group III source, the second Group III source and the nitrogen source into the growth chamber, growing a superlattice structure on the interface relaxation layer, thereby forming the warp control layer. 5. The uniformity control method of the homoepitaxial structure based on the nitride single crystal substrate according to claim 1 is characterized in that step S3 specifically includes: inputting a first Group III source, a second Group III source and a nitrogen source into the growth chamber, and controlling the flow rates of the first Group III source, the second Group III source and the nitrogen source to be below 200 sccm, and setting the gas pressure in the growth chamber to 30-70 torr, growing a superlattice structure on the interface relaxation layer, thereby forming the warp control layer. 6. A homoepitaxial structure based on a nitride single crystal substrate, characterized by comprising: A nitride single crystal substrate, wherein the thickness of the nitride single crystal substrate is greater than 1 μm; An interface relaxation layer grown on the substrate, the interface relaxation layer comprising a binary nitride layer, the constituent material of the binary nitride layer being lattice mismatched with the constituent material of the substrate to generate compressive stress or tensile stress, thereby balancing the warping of the substrate; the thickness of the interface relaxation layer is 1-10 nm; A warp regulation layer, which is grown on the interface relaxation layer, the surface of the warp regulation layer is flat, the warp regulation layer comprises a ternary nitride layer or a superlattice structure comprising the ternary nitride layer; the thickness of the ternary nitride layer is 10nm-100nm, and the thickness of the superlattice structure comprising the ternary nitride layer is 10nm-200nm; A semiconductor functional layer grown on the warp regulation layer; The nitride single crystal substrate is an AlN single crystal substrate, the binary nitride layer is a BN layer, the ternary nitride layer is a _{BxAl1 -xN} layer, the superlattice structure including the ternary nitride layer is a _{BxAl1 -xN} /AlN superlattice structure, and 0<x<1. 7. The homoepitaxial structure based on a nitride single crystal substrate according to claim 6 is characterized in that the lattice constant of the constituent material of the binary nitride layer is greater than the lattice constant of the constituent material of the substrate to generate tensile stress; or, the lattice constant of the constituent material of the binary nitride layer is smaller than the lattice constant of the constituent material of the substrate to generate compressive stress.