CN115116828A - Homoepitaxial structure based on nitride single crystal substrate and its uniformity control method - Google Patents

Abstract

The present application discloses a homoepitaxial structure based on a nitride single crystal substrate and a method for controlling the uniformity thereof. The uniformity control method includes: providing a nitride single crystal substrate containing a second group III element; growing an interface relaxation layer on the substrate, the interface relaxation layer comprising a binary nitride layer, and the The binary nitride layer includes a first group III element different from the second group III element to generate compressive or tensile stress to balance the warpage of the substrate; in the A warpage control layer is grown on the interface relaxation layer, and the warpage control layer includes a ternary nitride layer or a superlattice structure including the ternary nitride layer. In the present application, the controllable growth of the interface relaxation layer and the warpage control layer is carried out on the substrate, so as to realize the warpage controllable and high uniform growth of the homoepitaxial structure; at the same time, the prepared homoepitaxial structure is more flat, It has broad application prospects in optoelectronic 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, in particular to a homoepitaxial structure based on a nitride single crystal substrate and a uniformity control method thereof, belonging to the technical field of semiconductors.

Background technique

The growth of GaN-based devices is mostly based on heterogeneous substrates such as sapphire and silicon, and it is necessary to remove the mismatch by growing a transition layer from the substrate to obtain a GaN epitaxial layer. At the same time, the transition layer is also an important means to adjust the unevenness of the epitaxial wafer, thereby achieving the adjustment of the growth uniformity of the epitaxial wafer. For example, in the epitaxial growth of blue LEDs, when the quantum wells in the active region are grown, the In composition 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 warpage can usually be adjusted by adjusting the transition layer, so that the epitaxial wafer is as flat as possible during the growth of the quantum well, thereby ensuring wavelength uniformity.

For the homoepitaxial growth based on GaN single crystal substrate, since the substrate is already a GaN material layer and does not need any transition layer, the warpage value cannot be adjusted by the transition layer in the later growth. With different doping concentrations of epitaxial layer materials and the warpage of the GaN single crystal substrate itself at high temperatures, the temperature of the epitaxial wafer during growth will be affected, thereby affecting the uniformity of the epitaxial wafer. However, the current conventional growth methods do not have any technology and 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 the uniformity thereof, so as to overcome the deficiencies in the prior art.

In order to achieve the aforementioned purpose of the invention, 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 including a second group III element;

An interfacial relaxation layer is grown on the substrate, the interfacial relaxation layer includes a binary nitride layer, the binary nitride layer includes a first group III element, the first group III element and the second Different Group III elements to create compressive or tensile stress to balance the warpage of the substrate;

A warpage control layer is grown on the interface relaxation layer, the surface of the warpage control layer is flat, the warpage control layer includes a ternary nitride layer or a superlattice structure including a ternary nitride layer, the The ternary nitride layer includes 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 by comprising:

Nitride single crystal substrates,

an interface relaxation layer grown on the substrate, the interface relaxation layer comprising a binary nitride layer, and the constituent material of the binary nitride layer is lattice mismatched with the constituent material of the substrate, to generate compressive or tensile stress to balance the warpage of the substrate;

The warpage control layer is grown on the interface relaxation layer, the surface of the warpage control layer is flat, and the warpage control layer includes a ternary nitride layer or a superlattice structure including a ternary nitride layer.

Yet another aspect of the present application provides use of the nitride single crystal substrate-based homoepitaxial structure in the preparation of a UV-LED device or a GaN-based device.

Compared with the prior art, the present application firstly performs the controllable growth of the interface relaxation layer and the warpage control layer on the nitride single crystal substrate (specifically, through the composition and thickness of the interface relaxation layer and the warpage control layer. adjustment), thereby achieving high uniformity growth of the homoepitaxial structure; at the same time, the prepared homoepitaxial structure is more flat, and has broad application prospects in optoelectronic devices or electronic devices.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings that are used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

1a-1b are schematic diagrams of a homoepitaxial structure according to a typical embodiment of the present application, respectively.

Fig. 2 is the photoluminescence PL test pattern of the homoepitaxial structure sample A prepared in Example 1 of the application;

Fig. 3 is the photoluminescence PL test pattern of the homoepitaxial structure sample B prepared in Comparative Example 1 of the application;

FIG. 4 is a schematic diagram of the device for feeding the first group III source, the second group III source and the nitrogen source during the preparation of the interface relaxation layer and the warpage control layer in a typical embodiment of the present application.

Detailed ways

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

A method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate provided by some embodiments of the present application includes:

providing a nitride single crystal substrate, the substrate including a second group III element;

An interfacial relaxation layer is grown on the substrate, the interfacial relaxation layer includes a binary nitride layer, the binary nitride layer includes a first group III element, the first group III element and the second Different Group III elements to create compressive or tensile stress to balance the warpage of the substrate;

A warpage control layer is grown on the interface relaxation layer, the surface of the warpage control layer is flat, the warpage control layer includes a ternary nitride layer or a superlattice structure including a ternary nitride layer, the The ternary nitride layer includes 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 binary nitride The lattice constant of the constituent material of the layer is smaller 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 more than 1 μm.

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

In one embodiment, the thickness of the interfacial 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 pre-stress is tensile stress, the content of the first group III element in the binary nitride layer is 5 at. % to 10 at. The content of the first group III element in the superlattice structure is 5 at.% to 20 at.%.

Specifically, when the binary nitride layer is made of InN material, the ternary nitride layer is made of InGaN material, and the content of In element in the InGaN material is 5 at.% to 10 at.%, and the thickness of the ternary nitride layer is It is 10-50 nm, and the composition in the ternary nitride layer can be unchanged or the composition can be graded.

Specifically, when the binary nitride layer is an 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 5 at.%～ 20 at. %, the thickness of the superlattice structure including the ternary nitride layer is 10 to 200 nm.

In one embodiment, when the pre-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 ternary nitride layer containing the The content of the first group III element in the superlattice structure is 5 at. % to 100 at. %.

Specifically, when the binary nitride layer is an AlN material, the ternary nitride layer is an AlGaN single-layer material, the content of Al element in AlGaN is 5 at.% to 20 at.%, and the thickness of the ternary nitride layer is It is 10-100 nm, and the composition in the ternary nitride layer can be unchanged or the composition can be graded.

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

Further, the superlattice structure includes an InGaN/GaN superlattice structure, an AlGaN/GaN superlattice structure, etc., and 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 transformation between tensile stress and compressive stress can be flexibly realized. For example, the lattice constant of InN is larger than that of GaN. In this case, 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. However, the lattice constant of AlN is smaller than that of GaN. At this time, when Al(Ga)N is grown on the substrate, compressive stress will be introduced, causing the subsequently grown epitaxial layer to bend in a convex direction. However, due to the growth of heterogeneous layer materials, the lattices are not matched, and a material with good crystal quality such as a single crystal substrate is required as the base. Thus, the uniformity control method of the homoepitaxial structure of the nitride single crystal substrate in the present application is realized.

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

S1. Put the substrate into a growth chamber, and form a protective atmosphere in the growth chamber, then set the substrate temperature to the growth temperature of the binary nitride layer, and then grow the inputting the first group III source into the 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, and growing a binary nitride layer on the interface wetting layer, thereby forming an interface relaxation layer;

S3. Input the first group III source, the second group III source and the nitrogen source into the growth chamber, and grow a ternary nitride layer or a superlattice structure including a ternary nitride layer on the interface relaxation layer , thereby forming a warpage control layer.

Further, the first Group III source may be In, Al, Ga, B source, etc., and 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., and 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, and growing a superlattice structure on the interface relaxation layer, Thus, the warpage regulating layer is formed.

In one embodiment, step S3 specifically includes: inputting the first group III source, the second group III source and the nitrogen source into the growth chamber, and adding the first group III source, the second group III source and the nitrogen source to the growth chamber The flow rate of the source is controlled below 200 sccm, and the gas pressure in the growth chamber is set to 30-70 torr to grow a superlattice structure on the interface relaxation layer, thereby forming the warpage control layer.

For example, for the superlattice layer of AlGaN/GaN, by alternately feeding in the required Al source, Ga source and N source, alternately depositing films on the surface of the substrate, reducing the growth rate and improving the density of the lattice arrangement In addition, during the growth of the AlGaN/GaN superlattice layer, the airflow rate can be reduced to 200sccm; the pressure can be reduced to 30-70torr to improve the density of the lattice arrangement.

In one embodiment, during the preparation of the interface relaxation layer and the warpage control layer, a schematic diagram of the device for feeding the first group III source, the second group III source and the nitrogen source is shown in FIG. 4 .

In one embodiment, when the nitride single crystal substrate is a GaN single crystal substrate, the binary nitride layer is an AlN layer, and the ternary nitride layer is an AlxGa1 _{- xN} layer , the superlattice structure comprising 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 InyGa1 _{-yN layer} , and the The superlattice structure of the ternary nitride layer is 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, and the The superlattice structure of the ternary nitride layer is 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 B _x Al _1-x N layer, and the The superlattice structure of the ternary nitride layer is a BxAl1 _- xN/AlN superlattice structure, 0<x<1.

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

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

First, the growth of the interface relaxation layer is performed after the temperature is raised to the growth temperature of the InN-based or AlN-based material while the GaN single crystal substrate is protected by ammonia gas. When the ammonia gas needs to be disconnected, the organometallic source TMIn or TMAl is introduced, and the time is controlled within a few seconds. The purpose is to lay a layer of metal In atoms or metal Al atoms on the GaN single crystal substrate, and the function is to wet the substrate two. Sub-epitaxial interface layer. Then, ammonia gas is cut to grow InN or AlN material, and lattice relaxation is performed for the subsequent mismatch material, so as to grow the interface relaxation layer, and the thickness is controlled at 1-10 nm. The interfacial relaxation layer performs pre-relaxation and interfacial treatment for the growth warpage control layer to ensure the crystal quality and effective control of subsequent thicker materials.

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

This application proposes to deposit an interface relaxation layer on the GaN single crystal substrate first to prepare for the subsequent warpage control layer. The material of this layer is metal In/InN material or metal Al/AlN material, and then Al(In ) GaN material or superlattice material is the warpage control layer, and then the epitaxial structure is grown, such as the LED of the optoelectronic device or the HEMT structure of the electronic device. The present application realizes the adjustment of the unevenness of the entire epitaxial wafer by adjusting the composition and thickness of In(Ga)N or Al(Ga)N in the warpage control layer, so as to achieve controllable warpage and high uniformity of the epitaxial wafer growth.

In this application, in order to balance the warpage problem of the nitride single crystal substrate, the interfacial relaxation layer with a large lattice mismatch with the nitride single crystal substrate is first grown to balance the warpage of the substrate, and it can also be used as a subsequent warpage. The transition layer of the control layer improves the crystal quality; secondly, the warpage control layer of the subsequent growth is to gradually flatten the structure after the equilibrium warping, which can slow down the growth rate and make the lattice arrangement more dense, tensile stress or compressive stress. More uniform for better flatness.

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, and the constituent material of the binary nitride layer is lattice mismatched with the constituent material of the substrate, to generate compressive or tensile stress to balance the warpage of the substrate;

The warpage control layer is grown on the interface relaxation layer, the surface of the warpage control layer is flat, and the warpage control layer includes a ternary nitride layer or a superlattice structure including a ternary nitride layer.

In one embodiment, the homoepitaxial structure based on the nitride single crystal substrate further includes a semiconductor functional layer, and the semiconductor functional layer is grown on the warpage control 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, so as to generate tensile stress; or, the third The lattice constant of the constituent material of a group III nitride layer is smaller 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 more than 1 μm.

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

In one embodiment, the thickness of the interfacial 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 comprising 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, and the ternary nitride layer is an AlxGa1 _{- xN} layer , the superlattice structure comprising 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 InyGa1 _{-yN layer} , and the The superlattice structure of the ternary nitride layer is 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, and the The superlattice structure of the ternary nitride layer is 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 B _x Al _1-x N layer, and the The superlattice structure of the ternary nitride layer is a BxAl1 _{- xN} /AlN superlattice structure, 0<x<1.

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

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

Specifically, when the binary nitride layer is made of InN material, the ternary nitride layer is made of InGaN material, and the content of In element in the InGaN material is 5 at.% to 10 at.%, and the thickness of the ternary nitride layer is It is 10-50 nm, and the composition in the ternary nitride layer can be unchanged or the composition can be graded.

Specifically, when the binary nitride layer is an 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 5 at.%～ 20 at. %, the thickness of the superlattice structure including the ternary nitride layer is 10 to 200 nm.

In one embodiment, when the pre-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 ternary nitride layer containing the The content of the first group III element in the superlattice structure is 5 at. % to 100 at. %.

Specifically, when the binary nitride layer is an AlN material, the ternary nitride layer is an AlGaN single-layer material, the content of Al element in AlGaN is 5 at.% to 20 at.%, and the thickness of the ternary nitride layer is It is 10-100 nm, and the composition in the ternary nitride layer can be unchanged or the composition can be graded.

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

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

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

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 FIG. 1a, including a GaN single crystal substrate (the aforementioned nitride semiconductor single crystal substrate), which is sequentially grown on The interface relaxation layer and the warpage control layer on the substrate, and the N-type GaN region layer, the MQWs light-emitting layer, and the p-type GaN region layer (the aforementioned semiconductor functional layer) formed on the warpage control layer. The uniformity control of the N-type GaN region layer, the MQWs light-emitting layer, and the p-type GaN region layer is achieved through the interface relaxation layer and the warpage control layer.

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

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

Conventional GaN single crystal substrates are prone to concave phenomenon in homoepitaxy. Therefore, the embodiment takes the uniformity control method adopted to solve the concave phenomenon of the GaN single crystal substrate as an example.

Example 1

The GaN single crystal substrate is put into the MOCVD epitaxy system to grow the GaN homogenous LED epitaxial wafer, which is denoted as sample A.

First, the pressure was set to 70torr, the ammonia gas was turned on, and the temperature was raised to 1100 °C in the atmosphere of N ₂ carrier gas. After reaching equilibrium, the ammonia gas was turned off and the flow rate of TMAl was switched to 300sccm for 5s. layer of metal Al atoms. Then the ammonia gas was turned on again, and AlN was grown for about 1 min with a thickness of about 2 nm. So far, the growth of the interface relaxation layer is completed. Then, under the same conditions, Al source, Ga source and nitrogen source were simultaneously fed to grow AlGaN/GaN superlattice material, wherein the thickness of AlGaN was 3 nm, the content of Al element in AlGaN was 50%, and the thickness of GaN was 2nm, 30 cycles.

After completing the warpage control layer, grow the LED epitaxial structure with a thickness of 2 μm n-type GaN, followed by 5 cycles of InGaN/GaN quantum wells, where the content of In element in InGaN is 15%, the thickness is 3 nm, the thickness of GaN is 12 nm, and then the 200nm thick p-type GaN.

Comparative Example 1

The method is the same as in Example 1, except that the interface relaxation layer and the warpage control layer are not grown on the GaN single crystal substrate, and the prepared homogenous GaN epitaxial wafer is recorded as sample B.

The samples A and B in Example 1 and Comparative Example 1 were tested. Figures 2 to 3 are the photoluminescence PL test patterns of samples A and B. It can be seen that the conventional growth method (ie the solution in Comparative Example 1), due to the growth process of the GaN single crystal substrate and the subsequent cutting, grinding and polishing, is easy to bend the lattice and grow LEDs. In the case of the center depression, in the case of the dominant wavelength of 450 nm, the wavelength uniformity is 4.4 nm. However, after inserting the interface relaxation layer and the warpage control layer in Example 1 of the present application, the GaN homoepitaxial wafer sample A has the same dominant wavelength, and the wavelength uniformity is improved to 1.2 nm. This is the result of the curvature of the epitaxial wafer becoming convex, which verifies the effectiveness of the control method provided in this application.

Comparative Example 2

The method is the same as in Example 1, except that the interface relaxation layer is not grown on the GaN single crystal substrate (that is, the AlGaN/GaN superlattice material and the LED epitaxial structure are grown on the GaN single crystal substrate in turn), and the preparation The homogenous GaN epitaxial wafer is denoted as sample C.

Comparative Example 3

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

Example 2

The method is the same as that in Example 1, except that: when growing the warpage control layer, Al source, Ga source and nitrogen source are alternately input into the growth chamber, and the AlGaN/GaN superlattice is grown on the AlN interface relaxation layer. structure to form a warpage control layer.

Specifically, the flow rates of the Al source, Ga source and nitrogen source are controlled to be less than 200 sccm, and the gas pressure in the growth chamber is set to 30-70 torr to grow the AlGaN/GaN superlattice structure on the AlN interface relaxation layer, thereby A warpage control layer is formed.

The prepared homogenous GaN epitaxial wafer is denoted as sample E.

Example 3

The GaN single crystal substrate is put into the MOCVD epitaxy system to grow the GaN homogenous LED epitaxial wafer, which is denoted as sample F.

First, the pressure is set to 50torr, the ammonia gas is turned on, and the temperature is raised to 1100 °C in the atmosphere of N ₂ carrier gas. After reaching equilibrium, the TMAl flow is cut to 300 ccm while the ammonia gas is turned off, and the duration is 5s. layer of metal Al atoms. Then the ammonia gas was turned on again, and AlN was grown for about 1 min with a thickness of about 2 nm. So far, the growth of the interface relaxation layer is completed. Then, under the same conditions, AlGaN monolayer material growth is performed, wherein the thickness of AlGaN is 3 nm, the content of Al element in AlGaN is 10%, the thickness of GaN is 2 nm, and the period is 30. After completing the warpage control layer, grow the LED epitaxial structure with a thickness of 2 μm n-type GaN, followed by 5 cycles of InGaN/GaN quantum wells, where the content of In element in InGaN is 15%, the thickness is 3 nm, the thickness of GaN is 12 nm, and then the 200nm thick p-type GaN.

Example 4

The AlN single crystal substrate is put into the MOCVD epitaxy system to grow the AlN homogenous UV-LED epitaxial wafer, which is denoted as sample G.

First, the pressure is set to 30torr, the ammonia gas is turned on, and the temperature is raised to 1100 °C in the atmosphere of N ₂ carrier gas. After reaching equilibrium, the ammonia gas is turned off and the flow rate of the B source is switched to 200 ccm for 5s. The surface of the single crystal substrate is spread about A layer of B atoms. Then the ammonia gas was turned on again, and BN was grown for about 1 min with a thickness of about 2 nm. So far, the growth of the interface relaxation layer is completed. Then, under the same conditions, the superlattice material growth of BN/AlN was carried out, wherein the thickness of BN was 3 nm, the thickness of AlN was 2 nm, and the period was 25. After completing the warpage control layer, grow a UV-LED epitaxial structure with a thickness of 2μm n-type AlGaN, followed by 5 cycles of AlGaN/GaN quantum wells, where the content of Al element in AlGaN is 50%, the thickness is 3nm, and the thickness of GaN is 12nm. Then there is p-type AlGaN with a thickness of 200 nm.

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

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

Finally, it should be noted that the above are only the preferred embodiments of the present application, and are not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the The technical solutions described in the foregoing embodiments can be modified, or some technical features thereof can be equivalently replaced, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included. within the scope of protection of this application.

Claims (10)

1. a uniformity control method based on the homoepitaxial structure of a nitride single crystal substrate, is characterized in that, comprising: providing a nitride single crystal substrate, the substrate including a second group III element; An interfacial relaxation layer is grown on the substrate, the interfacial relaxation layer includes a binary nitride layer, the binary nitride layer includes a first group III element, the first group III element and the second Different Group III elements to create compressive or tensile stress to balance the warpage of the substrate; A warpage control layer is grown on the interface relaxation layer, the surface of the warpage control layer is flat, the warpage control layer includes a ternary nitride layer or a superlattice structure including a ternary nitride layer, the The ternary nitride layer includes a first group III element and a second group III element. 2 . The method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate according to claim 1 , wherein the lattice constant of the constituent material of the binary nitride layer is greater than that of the nitride. 3 . the lattice constant of the constituent material of the single crystal 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 nitride single crystal substrate, to generate compressive stress. 3 . The uniformity control method of the homoepitaxial structure based on a nitride single crystal substrate according to claim 1 , wherein the thickness of the nitride single crystal substrate is more than 1 μm; 4 . And/or, the thickness of the interface relaxation layer is 1-10 nm; And/or, the thickness of the ternary nitride layer is 10 nm-100 nm, and the thickness of the superlattice structure comprising the ternary nitride layer is 10 nm-200 nm. 4 . The method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate according to claim 3 , wherein the thickness of the nitride single crystal substrate is 1-2.5 μm. 5 . 5. The method for regulating the uniformity of a homoepitaxial structure based on a nitride single crystal substrate according to any one of claims 1-4, wherein the method specifically comprises: S1. Put the substrate into a growth chamber, and form a protective atmosphere in the growth chamber, then set the substrate temperature to the growth temperature of the binary nitride layer, and then grow the inputting the first group III source into the 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, and growing a binary nitride layer on the interface wetting layer, thereby forming an interface relaxation layer; S3. Input the first group III source, the second group III source and the nitrogen source into the growth chamber, and grow a ternary nitride layer or a superlattice structure including a ternary nitride layer on the interface relaxation layer , thereby forming a warpage control layer. 6 . The method for controlling the uniformity of a homoepitaxial structure based on a nitride single crystal substrate according to claim 5 , wherein step S3 specifically comprises: combining the first group III source and the second group III source and nitrogen sources are alternately input into the growth chamber to grow a superlattice structure on the interface relaxation layer, thereby forming the warpage control layer. And/or, step S3 specifically includes: inputting the first group III source, the second group III source, and the nitrogen source into the growth chamber, and mixing the first group III source, the second group III source, and the nitrogen source into the growth chamber. The flow rate is controlled below 200 sccm, and the gas pressure in the growth chamber is set to 30-70 torr to grow a superlattice structure on the interface relaxation layer, thereby forming the warpage control layer. 7. The uniformity control method of the homoepitaxial structure based on the nitride single crystal substrate according to claim 5, is characterized in that: 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} , and the ternary nitride layer includes a ternary nitride layer. The superlattice structure of the 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 InyGa1 _{-yN layer} , and the The superlattice structure of the ternary nitride layer is 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, and the The superlattice structure of the ternary nitride layer is 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 B _x Al _1-x N layer, and the The superlattice structure of the ternary nitride layer is a B _x Al _1-x N/AlN superlattice structure, 0<x<1; And/or, the uniformity control method further includes: growing a semiconductor functional layer on the warpage control layer. 8. A homoepitaxial structure based on a nitride single crystal substrate, characterized in that, comprising: Nitride single crystal substrates, an interface relaxation layer grown on the substrate, the interface relaxation layer comprising a binary nitride layer, and the constituent material of the binary nitride layer is lattice mismatched with the constituent material of the substrate, to generate compressive or tensile stress to balance the warpage of the substrate; The warpage control layer is grown on the interface relaxation layer, the surface of the warpage control layer is flat, and the warpage control layer includes a ternary nitride layer or a superlattice structure including a ternary nitride layer. 9 . The homoepitaxial structure based on a nitride single crystal substrate according to claim 8 , further comprising a semiconductor functional layer, and the semiconductor functional layer is grown on the warpage control layer; 9 . And/or, 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 constituent material of the first group III nitride layer The lattice constant is less than the lattice constant of the constituent material of the substrate to generate compressive stress; And/or, the thickness of the nitride single crystal substrate is more than 1 μm; And/or, the thickness of the interface relaxation layer is 1-10 nm; And/or, the thickness of the ternary nitride layer is 10 nm-100 nm, and the thickness of the superlattice structure comprising the ternary nitride layer is 10 nm-200 nm. 10. The homoepitaxial structure based on a nitride single crystal substrate according to claim 8, wherein: 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} , and the ternary nitride layer includes a ternary nitride layer. The superlattice structure of the 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 InyGa1 _{-yN layer} , and the The superlattice structure of the ternary nitride layer is 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, and the The superlattice structure of the ternary nitride layer is 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 B _x Al _1-x N layer, and the The superlattice structure of the ternary nitride layer is a BxAl1 _{- xN} /AlN superlattice structure, 0<x<1.

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