AlGaN film growth method and AlGaN film

Abstract

The invention provides an AlGaN film growth method and an AlGaN film, relates to the technical field of semiconductor material epitaxy, and aims to solve the technical problem of high defect density of an AlGaN film grown based on a silicon carbide substrate in the prior art. The method comprises the following steps: preparing a substrate, and cleaning the substrate; putting the cleaned substrate into high-temperature MOCVD (Metal Organic Chemical Vapor Deposition) equipment, and introducing a metal organic source for appointed time, so that metal atoms are adsorbed on the growth surface of the substrate; carrying out metal atom desorption treatment on the substrate adsorbed with the metal atoms for a specified time to obtain a target substrate; and growing an AlGaN film on the growth surface of the target substrate. According to the method, the step density of the surface of the substrate is reduced through metal atom adsorption and desorption processes, and an oxide layer on the surface is effectively removed, so that the crystal quality and the surface smoothness of the AlGaN film are improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor material epitaxy, and more specifically, to an AlGaN film growth method and an AlGaN film. Background Art

[0002] Group III nitrides and their alloys can cover the wavelength range from infrared to ultraviolet by adjusting the bandgap width (0.7-6.2 eV), providing a broad development space for optoelectronic devices. The alloy composed of gallium nitride (GaN) and aluminum nitride (AlN) materials can realize an ultraviolet light source with an emission wavelength of 210-400 nm. Compared with traditional ultraviolet light sources such as fragile and unreliable mercury lamps, ultraviolet solid-state light sources have a wide range of market application needs in the fields of air and water purification, sterilization and disinfection, photolithography, ultraviolet curing, high-density information storage, biochemical detection and non-line-of-sight communication due to their advantages such as small size, precise and adjustable wavelength, high energy efficiency, non-toxic and environmentally friendly, long life and durability.

[0003] The material quality of AlGaN is one of the main factors affecting the performance of ultraviolet optoelectronic devices. Sapphire is currently a universal substrate for ultraviolet optoelectronic devices, but there is a considerable lattice mismatch and thermal mismatch between sapphire and AlGaN, which will cause a large number of dislocations in the epitaxial layer to act as non-radiative recombination centers and light scattering centers, reducing the internal quantum efficiency. Secondly, sapphire has disadvantages such as insulation and poor thermal conductivity, which seriously affect the life and reliability of the device. Compared with sapphire, silicon carbide (SiC) substrates are theoretically more suitable for growing AlGaN materials. The lattice mismatch and thermal mismatch between silicon carbide and AlGaN are small, and the two have similar crystal structures, which helps to obtain higher quality AlGaN epitaxial layers; secondly, silicon carbide substrates have the advantages of good chemical stability, good electrical conductivity, good thermal conductivity, and easy peeling. Silicon carbide substrates are not inferior to ideal AlN single crystal substrates, and silicon carbide substrates are easier to obtain and have lower costs than AlN substrates. However, in the prior art, AlGaN films grown on silicon carbide substrates have a high defect density. Summary of the invention

[0004] In view of this, the present disclosure provides an AlGaN film growth method and an AlGaN film, so as to solve the technical problem of high defect density in the AlGaN film grown on a silicon carbide substrate in the prior art.

[0005] One aspect of the present disclosure provides an AlGaN thin film growth method, comprising: preparing a substrate and cleaning the substrate; placing the cleaned substrate into a high-temperature MOCVD device, introducing a metal organic source for a specified time to adsorb metal atoms on a growth surface of the substrate; performing a metal atom desorption treatment on the substrate after the metal atoms are adsorbed for a specified time to obtain a target substrate; and growing an AlGaN thin film on the growth surface of the target substrate.

[0006] According to an embodiment of the present disclosure, the material of the substrate includes: one of aluminum nitride, gallium nitride, silicon carbide and silicon.

[0007] According to an embodiment of the present disclosure, the temperature of the substrate during the metal atom adsorption process or the metal atom desorption process is 800-1500° C., and the temperature does not exceed the thermal decomposition temperature corresponding to the substrate material.

[0008] According to an embodiment of the present disclosure, when the substrate is in the process of metal atom adsorption or metal atom desorption, the chamber pressure of the MOCVD equipment is 10-300 Torr.

[0009] According to an embodiment of the present disclosure, the metal organic source includes one of trimethylaluminum, triethylaluminum, trimethylgallium, triethylgallium, trimethylindium, triethylindium and triethylboron.

[0010] According to the embodiments of the present disclosure, the metal atom adsorption process and the metal atom desorption process of the substrate can be operated in multiple cycles to adjust the step density on the substrate surface and remove oxygen impurities on the growth surface of the substrate.

[0011] According to the embodiment of the present disclosure, the AlGaN film is a single layer or a multi-layer Al x Ga 1-x N (0≤x≤1) films.

[0012] According to an embodiment of the present disclosure, before growing an AlGaN film on the growth surface of a target substrate, the method further includes: growing an AlN layer as a buffer layer and a transition layer on the growth surface of the target substrate.

[0013] According to an embodiment of the present disclosure, growing an AlN layer as a buffer layer and a transition layer on the growth surface of the target substrate includes: growing an AlN nucleation layer on the growth surface of the target substrate; and growing an AlN high-temperature layer on the surface of the AlN nucleation layer.

[0014] Another aspect of the present disclosure provides an AlGaN film, the structure of which includes: a substrate; an AlN nucleation layer grown on the substrate; an AlN high-temperature layer grown on the AlN nucleation layer; and an AlGaN film grown on the AlN high-temperature layer.

[0015] The AlGaN thin film growth method and AlGaN thin film provided by the embodiments of the present disclosure have at least the following beneficial effects:

[0016] (1) The AlGaN thin film growth method and the AlGaN thin film provided in the embodiments of the present disclosure reduce the step density on the substrate surface through the metal atom adsorption and desorption process, effectively remove the surface oxide layer, thereby improving the crystal quality and surface smoothness of the AlGaN thin film.

[0017] (2) The AlGaN thin film growth method and AlGaN thin film provided in the embodiments of the present disclosure reduce the step density on the substrate surface through the metal atom adsorption and desorption process, effectively remove the surface oxide layer, and at the same time increase the tensile stress of the AlN epitaxial layer, reduce the lattice mismatch between AlN and AlGaN, and ultimately improve the crystal quality and surface smoothness of the epitaxial layer. This method is not only applicable to silicon carbide substrates, but also to the surface pretreatment of heterogeneous substrates such as aluminum nitride, gallium nitride, and silicon, and the growth of AlGaN thin films thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0019] Figure 1 A flow chart schematically shows a method for growing an AlGaN thin film according to an embodiment of the present disclosure;

[0020] Figure 2 Schematically showing an atomic force microscope image of the growth surface of the 4H-SiC substrate before and after pretreatment according to an embodiment of the present disclosure;

[0021] Figure 3 Schematically shows an X-ray photoelectron spectrum of the growth surface of the 4H-SiC substrate before and after pretreatment according to an embodiment of the present disclosure;

[0022] Figure 4 Schematically showing a comparison of Raman spectra of AlN films grown on 4H-SiC substrates without TMAl pretreatment and with TMAl pretreatment according to an embodiment of the present disclosure;

[0023] Figure 5 The structure of the AlGaN thin film grown according to the AlGaN thin film growth method of the first embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] Group III nitrides and their alloys can cover the wavelength range from infrared to ultraviolet by adjusting the bandgap width (0.7-6.2 eV), providing a broad development space for optoelectronic devices. The alloy composed of gallium nitride (GaN) and aluminum nitride (AlN) materials can realize an ultraviolet light source with an emission wavelength of 210-400 nm. Compared with traditional ultraviolet light sources such as fragile and unreliable mercury lamps, ultraviolet solid-state light sources have a wide range of market application needs in the fields of air and water purification, sterilization and disinfection, photolithography, ultraviolet curing, high-density information storage, biochemical detection and non-line-of-sight communication due to their advantages such as small size, precise and adjustable wavelength, high energy efficiency, non-toxic and environmentally friendly, long life and durability.

[0029] The material quality of AlGaN is one of the main factors affecting the performance of ultraviolet optoelectronic devices. Sapphire is currently a universal substrate for ultraviolet optoelectronic devices, but there is a considerable lattice mismatch and thermal mismatch between sapphire and AlGaN, which will cause a large number of dislocations in the epitaxial layer to act as non-radiative recombination centers and light scattering centers, reducing the internal quantum efficiency. Secondly, sapphire has disadvantages such as insulation and poor thermal conductivity, which seriously affect the life and reliability of the device. Compared with sapphire, silicon carbide (SiC) substrates are theoretically more suitable for growing AlGaN materials. The lattice mismatch and thermal mismatch between silicon carbide and AlGaN are small, and the two have similar crystal structures, which helps to obtain higher quality AlGaN epitaxial layers; secondly, silicon carbide substrates have the advantages of good chemical stability, good electrical conductivity, good thermal conductivity, and easy peeling. Silicon carbide substrates are not inferior to ideal AlN single crystal substrates, and silicon carbide substrates are easier to obtain and have lower costs than AlN substrates.

[0030] However, there are certain technical challenges in the epitaxy of AlGaN on silicon carbide substrates. Silicon carbide and AlGaN have different atomic stacking modes. SiC substrates are generally treated with chemical mechanical polishing to form steps with a height of two atomic layers. The stacking order of AlGaN grown on different steps of the silicon carbide substrate follows the stacking order of the silicon carbide below, so the AlGaN layer boundaries of adjacent steps may be irrelevant, which will form planar defects. With the increase of layer thickness, the energy of planar defects increases with the increase of the cross-sectional area of ​​the defect boundary. Coupled with the accumulation of mismatch strain energy, these strains are released in the form of stacking faults or dislocations. At the same time, the surface of the silicon carbide substrate is easily oxidized, and the oxygen impurities on the surface will cause the initial growth mode of the AlGaN epitaxial layer to be three-dimensional growth. The columnar structure formed by three-dimensional island growth is easy to introduce high-density dislocations during the coalescence process due to the large in-plane orientation difference, which deteriorates the surface morphology. Although conventional hydrochloric acid / hydrofluoric acid ex situ treatment can remove the oxide layer on the surface of the substrate, some oxygen impurities will be adsorbed on the surface after being placed in the growth chamber, which is difficult to be completely removed.

[0031] Based on this, the embodiment of the present disclosure provides an AlGaN film growth method to solve the technical problem of high defect density in AlGaN films grown on silicon carbide substrates in the prior art. The method includes: preparing a substrate and cleaning the substrate; placing the cleaned substrate into a high-temperature MOCVD device, introducing a metal organic source for a specified time, so that metal atoms are adsorbed on the growth surface of the substrate; performing a metal atom desorption treatment on the substrate after the metal atoms are adsorbed for a specified time to obtain a target substrate; and growing an AlGaN film on the growth surface of the target substrate.

[0032] The AlGaN thin film growth method provided in the embodiment of the present disclosure reduces the step density on the substrate surface through the metal atom adsorption and desorption process, effectively removes the surface oxide layer, thereby improving the crystal quality and surface smoothness of the AlGaN thin film.

[0033] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0034] Figure 1 The flowchart of the AlGaN thin film growth method according to an embodiment of the present disclosure is schematically shown.

[0035] like Figure 1 As shown, the AlGaN thin film growth method of the embodiment of the present disclosure may include, for example, operations S1 to S4.

[0036] In operation S1, a substrate is prepared and a cleaning process is performed on the substrate.

[0037] In operation S2, the cleaned substrate is placed in a high-temperature MOCVD device (Metal Organic Chemical Vapor Deposition), and a metal organic source is introduced for a specified time to allow metal atoms to be adsorbed on the growth surface of the substrate.

[0038] In operation S3, the substrate on which the metal atoms are adsorbed is subjected to a metal atom desorption process for a specified time to obtain a target substrate.

[0039] In operation S4, an AlGaN thin film is grown on a growth surface of the target substrate.

[0040] In this embodiment, the material of the substrate may be a heterogeneous substrate such as aluminum nitride, gallium nitride, silicon carbide, and silicon.

[0041] The key to this method is to reduce the step density on the substrate surface through the metal atom adsorption and desorption processes, effectively remove the surface oxide layer, thereby improving the crystal quality and surface smoothness of the AlGaN film.

[0042] The operation S2 is a process of metal atom adsorption on the substrate, and the operation S3 is a process of metal atom desorption on the substrate.

[0043] The AlGaN thin film growth method provided in the embodiment of the present disclosure reduces the step density on the substrate surface through the metal atom adsorption and desorption process, effectively removes the surface oxide layer, thereby improving the crystal quality and surface smoothness of the AlGaN thin film.

[0044] According to an embodiment of the present disclosure, the temperature of the substrate during the metal atom adsorption process or the metal atom desorption process is 800-1500° C., and the temperature does not exceed the thermal decomposition temperature corresponding to the substrate material.

[0045] According to an embodiment of the present disclosure, when the substrate is in the process of metal atom adsorption or metal atom desorption, the chamber pressure of the MOCVD equipment is 10-300 Torr.

[0046] According to an embodiment of the present disclosure, the metal organic source includes one of trimethylaluminum, triethylaluminum, trimethylgallium, triethylgallium, trimethylindium, triethylindium and triethylboron.

[0047] According to the embodiments of the present disclosure, the metal atom adsorption process and the metal atom desorption process of the substrate can be operated in multiple cycles to adjust the step density on the substrate surface and remove oxygen impurities on the growth surface of the substrate.

[0048] According to the embodiment of the present disclosure, the AlGaN film is a single layer or a multi-layer Al x Ga 1-x N (0≤x≤1) films.

[0049] According to an embodiment of the present disclosure, before growing an AlGaN film on the growth surface of a target substrate, the method further includes: growing an AlN layer as a buffer layer and a transition layer on the growth surface of the target substrate.

[0050] According to an embodiment of the present disclosure, growing an AlN layer as a buffer layer and a transition layer on the growth surface of the target substrate includes: growing an AlN nucleation layer on the growth surface of the target substrate; and growing an AlN high-temperature layer on the surface of the AlN nucleation layer.

[0051] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, two preferred embodiments (embodiment 1 and embodiment 2) are provided below to further describe the present disclosure in detail.

[0052] Embodiment 1:

[0053] In this embodiment, 4H-SiC is selected as the material of the substrate, and then trimethylaluminum (TMAl), trimethylgallium (TMGa) and NH3 are used as Al source, Ga source and N source respectively. After pre-treating the growth surface of the substrate, a high-quality AlN transition layer is grown by a two-step method, and a high-quality AlGaN film is further grown on this basis. Specifically:

[0054] First, prepare the silicon carbide substrate and perform organic and inorganic cleaning to remove organic contaminants and inorganic metal particles on the substrate surface. For example, the silicon carbide substrate is sequentially placed in a concentrated sulfuric acid / hydrogen peroxide mixed solution (or acetone, isopropanol organic solution), a hydrofluoric acid solution (or a dilute acid solution such as dilute hydrochloric acid), and deionized water for cleaning, and finally blown dry with a nitrogen gun.

[0055] Then, the cleaned silicon carbide substrate is placed in the MOCVD device, and the growth surface of the silicon carbide substrate is subjected to surface pretreatment, preferably the growth surface of the silicon surface is subjected to surface pretreatment. During the surface pretreatment, the chamber pressure of the MOCVD device is preferably 10-300 Torr, and the substrate is heated to a temperature of 800-1500 ° C in a H2 atmosphere. It should be noted here that the heating temperature should not exceed the thermal decomposition temperature of the substrate.

[0056] Next, a metal organic source is introduced at a certain flow rate and for a certain time to adsorb metal atoms on the growth surface of the substrate. The metal organic source here can be common sources such as trimethylaluminum, triethylaluminum, trimethylgallium, triethylgallium, trimethylindium, triethylindium, and triethylboron. The flow rate of the metal organic source is adjusted according to the model of the MOCVD equipment. In this embodiment, a trimethylaluminum source with a flow rate of 1-100 μmol / min is preferably used for Al atom adsorption. The introduction time of the metal organic source is preferably 1-300 s.

[0057] Subsequently, the metal organic source is turned off to carry out the desorption process of the metal atoms adsorbed on the surface. During this process, the continuous introduction of H2 carrier gas should be maintained to rebuild the growth surface of the substrate with the help of the etching effect of H2, and avoid the introduction of gases such as N2 and NH3 to avoid the formation of SiN on the growth surface of the substrate. x The closing time of the metal organic source is preferably 1-2000 s. When the metal organic source selected is a trimethylaluminum source, the Al atoms adsorbed on the growth surface of the substrate react with the surface oxide to produce volatile suboxides, which evaporate at high temperature, fully desorb the aluminum atoms and remove the oxide layer on the surface of the substrate, and finally obtain a pretreated substrate, i.e., a target substrate.

[0058] In this embodiment, the metal atom adsorption process and the metal atom desorption process of the substrate can be cycled 1-200 times to fully regulate the step density on the surface of the silicon carbide substrate and remove oxygen impurities on the growth surface; the introduction and closing time of the metal organic source in different cycle periods can be flexibly adjusted.

[0059] After heat treatment, the growth surface of the silicon carbide substrate undergoes morphological and chemical changes. For specific changes, refer to Figure 2 and Figure 3 .

[0060] Figure 2Schematically shows an atomic force microscope image of the growth surface of the 4H-SiC substrate before and after pretreatment according to an embodiment of the present disclosure.

[0061] like Figure 2 As shown, driven by the natural minimization of surface free energy, the step density on the substrate growth surface is reduced while still maintaining a smooth atomic step flow.

[0062] Figure 3 The X-ray photoelectron spectrum of the growth surface of the 4H-SiC substrate before and after pretreatment according to the embodiment of the present disclosure is schematically shown.

[0063] like Figure 3 As shown in the figure, the peak intensity related to oxygen atoms on the growth surface of the substrate after pretreatment is significantly reduced, indicating that the oxygen impurities on the growth surface of the substrate have been effectively reduced or removed. This helps to prepare higher quality and smoother AlN and AlGaN films in the subsequent preparation.

[0064] On the pretreated silicon carbide substrate, an AlN layer is grown as a transition layer by a two-step method. In this embodiment, the chamber pressure is preferably 30-50 Torr, the growth temperature is adjusted to 600-1100 °C, TMAl and NH3 are introduced, and an AlN nucleation layer with a thickness of 5-200 nm is grown; then, the temperature is increased to 1000-1500 °C, and a high-quality AlN high-temperature layer with a thickness of 50-2000 nm is grown.

[0065] Figure 4 Schematically showing a comparison of Raman spectra of AlN films grown on 4H-SiC substrates without TMAl pretreatment and with TMAl pretreatment according to an embodiment of the present disclosure.

[0066] like Figure 4 As shown in Figure 2, the AlN film grown on the substrate growth surface after the above pretreatment has a higher tensile stress. This can relieve the tension between the AlN film and the subsequently grown Al x Ga 1-x N (0≤x≤1) films, thereby reducing the dislocations caused by lattice mismatch. Specifically, during the pretreatment process, the long-term etching effect of hydrogen causes some uneven areas on the step edges of the growth surface of the substrate. The tensile stress introduced by the AlN islands grown on these areas during the merging process increases, so the tensile stress of the AlN film increases.

[0067] Finally, AlGaN film is continued to grow on the AlN transition layer, TMAl, TMGa and NH3 are introduced into the chamber, and the growth temperature is 900-1200°C; the gas phase molar ratio of the metal organic source is adjusted to obtain an AlGaN film of the target component.

[0068] In this embodiment, optionally, a composition gradient structure or AlGaN film may be used between the AlN film and the AlGaN film. x Ga 1-x N / A y Ga 1-y N superlattice (0≤x, y≤1, x≠y) structure, intermediate component layer, intermediate temperature layer and other inserted layers are used to regulate the stress on the AlGaN film.

[0069] The AlGaN thin film growth method provided by the embodiment of the present disclosure reduces the step density on the substrate surface through the metal atom adsorption and desorption process, effectively removes the surface oxide layer, and can increase the tensile stress of the AlN epitaxial layer, reduce the lattice mismatch between AlN and AlGaN, and ultimately improve the crystal quality and surface smoothness of the epitaxial layer. This method is not only applicable to silicon carbide substrates, but also to the surface pretreatment of heterogeneous substrates such as aluminum nitride, gallium nitride, and silicon, and the growth of AlGaN films thereon.

[0070] Embodiment 2:

[0071] In this embodiment, SiC is selected as the material of the substrate, and TMAl, TMGa and NH3 are used as Al source, Ga source and N source respectively. After the growth surface of the substrate is pretreated, a high-quality AlGaN film is directly grown. Specifically:

[0072] First, prepare the silicon carbide substrate and perform organic and inorganic cleaning to remove organic contaminants and inorganic metal particles on the substrate surface. For example, the silicon carbide substrate is sequentially placed in a concentrated sulfuric acid / hydrogen peroxide mixed solution (or acetone, isopropanol organic solution), a hydrofluoric acid solution (or a dilute acid solution such as dilute hydrochloric acid), and deionized water for cleaning, and finally blown dry with a nitrogen gun.

[0073] Then, the silicon carbide substrate is placed in the MOCVD device, and the growth surface of the silicon carbide substrate is subjected to surface pretreatment, preferably the growth surface of the silicon surface is subjected to surface pretreatment. During the surface pretreatment, the chamber pressure of the MOCVD device is preferably 10-300 Torr, and the substrate is heated to a temperature of 800-1500° C. in a H2 atmosphere. It should be noted here that the heating temperature should not exceed the thermal decomposition temperature of the substrate.

[0074] Next, a metal organic source is introduced at a certain flow rate and for a certain time to adsorb metal atoms on the growth surface of the substrate. The metal organic source here can be common sources such as trimethylaluminum, triethylaluminum, trimethylgallium, triethylgallium, trimethylindium, triethylindium, and triethylboron. The flow rate of the metal organic source is adjusted according to the model of the MOCVD equipment. In this embodiment, a trimethylaluminum source with a flow rate of 1-100 μmol / min is preferably used for Al atom adsorption. The introduction time of the metal organic source is preferably 1-300 s.

[0075] Subsequently, the metal organic source is turned off to carry out the desorption process of the metal atoms adsorbed on the surface. In this process, the continuous introduction of H2 carrier gas should be maintained to rebuild the substrate growth surface with the help of the etching effect of H2, and avoid the introduction of gases such as N2 and NH3 to avoid the formation of SiNx on the substrate growth surface. The closing time of the metal organic source is preferably 1-2000 s. When the metal organic source selected is a trimethylaluminum source, the Al atoms adsorbed on the substrate growth surface react with the surface oxide to produce volatile suboxides, which evaporate at high temperature, fully desorb aluminum atoms and remove the oxide layer on the substrate surface.

[0076] In this embodiment, the metal atom adsorption process and the metal atom desorption process of the substrate can be cycled 1-200 times to fully regulate the step density on the surface of the silicon carbide substrate and remove oxygen impurities on the growth surface; the introduction and closing time of the metal organic source in different cycle periods can be flexibly adjusted.

[0077] After heat treatment, the growth surface of the silicon carbide substrate undergoes morphological and chemical changes. For specific changes, refer to Figure 2 and Figure 3 .

[0078] Figure 2 Schematically shows an atomic force microscope image of the growth surface of the 4H-SiC substrate before and after pretreatment according to an embodiment of the present disclosure.

[0079] like Figure 2 As shown, driven by the natural minimization of surface free energy, the step density on the substrate growth surface is reduced while still maintaining a smooth atomic step flow.

[0080] Figure 3 The X-ray photoelectron spectrum of the growth surface of the 4H-SiC substrate before and after pretreatment according to the embodiment of the present disclosure is schematically shown.

[0081] like Figure 3 As shown in the figure, the peak intensity related to oxygen atoms on the growth surface of the substrate after pretreatment is significantly reduced, indicating that the oxygen impurities on the growth surface of the substrate have been effectively reduced or removed. This is conducive to the subsequent preparation of higher quality and smoother AlGaN films.

[0082] Grow AlGaN film on the growth surface of pre-treated silicon carbide substrate. Introduce TMAl, TMGa and NH3 into the chamber, the growth temperature is 900-1200 ℃; adjust the gas phase molar ratio of metal organic source to obtain AlGaN film of target component.

[0083] In this embodiment, optionally, a composition gradient structure or AlGaN film may be used between the silicon carbide substrate and the AlGaN film. x Ga 1-xN / A y Ga 1-y N superlattice (0≤x, y≤1, x≠y) structure, intermediate component layer, intermediate temperature layer and other insertion layers are used to relieve the stress on AlGaN film.

[0084] The present disclosure also provides an AlGaN film grown according to the AlGaN film growth method of the first embodiment. The specific structure is shown in Figure 5 .

[0085] Figure 5 The structure of the AlGaN thin film grown according to the AlGaN thin film growth method of the first embodiment of the present disclosure is schematically shown.

[0086] like Figure 5 As shown, the AlGaN film grown by the AlGaN film growth method according to the first embodiment of the present disclosure has a structure comprising:

[0087] Substrate.

[0088] An AlN nucleation layer is grown on the substrate.

[0089] An AlN high temperature layer is grown on the AlN nucleation layer.

[0090] An AlGaN thin film is grown on the AlN high temperature layer.

[0091] Since the AlGaN film is grown according to the AlGaN film growth method of the first embodiment of the present disclosure, its detailed structure and beneficial effects can be referred to the AlGaN film growth method of the first embodiment of the present disclosure, and therefore, they are not described in detail here.

[0092] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present disclosure can be combined and / or combined in a variety of ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0093] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for growing an AlGaN thin film, characterized in that: The method comprises: preparing a substrate and performing a cleaning process on the substrate; The cleaned substrate is placed in a high-temperature MOCVD device, and a metal organic source is introduced for a specified time to allow metal atoms to be adsorbed on the growth surface of the substrate; Performing a metal atom desorption process on the substrate after the metal atoms are adsorbed for a specified time to obtain a target substrate; An AlGaN thin film is grown on the growth surface of the target substrate.

2. The AlGaN thin film growth method according to claim 1, characterized in that: The material of the substrate includes: one of aluminum nitride, gallium nitride, silicon carbide and silicon.

3. The AlGaN thin film growth method according to claim 2, characterized in that: The temperature of the substrate during the metal atom adsorption process or the metal atom desorption process is 800-1500° C., and the temperature does not exceed the thermal decomposition temperature corresponding to the substrate material.

4. The AlGaN thin film growth method according to claim 2, characterized in that: During the metal atom adsorption process or metal atom desorption process of the substrate, the chamber pressure of the MOCVD device is 10-300 Torr.

5. The AlGaN thin film growth method according to claim 1, characterized in that: The metal organic source includes: one of trimethylaluminum, triethylaluminum, trimethylgallium, triethylgallium, trimethylindium, triethylindium and triethylboron.

6. The AlGaN thin film growth method according to claim 1, characterized in that: The metal atom adsorption process and the metal atom desorption process of the substrate can be operated in cycles for multiple times, thereby regulating the step density on the surface of the substrate and removing oxygen impurities on the growth surface of the substrate.

7. The AlGaN thin film growth method according to claim 1, characterized in that: The AlGaN film is a single layer or a multi-layer Al x Ga 1-x N (0≤x≤1) films.

8. The AlGaN thin film growth method according to any one of claims 1 to 7, characterized in that: Before growing the AlGaN film on the growth surface of the target substrate, the method further comprises: An AlN layer is grown on the growth surface of the target substrate as a buffer layer and a transition layer.

9. The AlGaN thin film growth method according to claim 8, characterized in that: The step of growing an AlN layer as a buffer layer and a transition layer on the growth surface of the target substrate comprises: Growing an AlN nucleation layer on the growth surface of the target substrate; An AlN high temperature layer is grown on the surface of the AlN nucleation layer.

10. An AlGaN thin film, characterized in that: The AlGaN film is prepared by the AlGaN film growth method according to any one of claims 1 to 9, and the structure of the AlGaN film includes: substrate; an AlN nucleation layer grown on the substrate; an AlN high temperature layer grown on the AlN nucleation layer; An AlGaN film is grown on the AlN high temperature layer.

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