A beta-ga2o3 epitaxial structure and a method for manufacturing the same

Abstract

The application provides a beta-Ga2O3 epitaxial structure and a manufacturing method thereof. The beta-Ga2O3 epitaxial structure comprises a substrate and a beta-Ga2O3 epitaxial layer on the substrate. The beta-Ga2O3 epitaxial layer comprises a plurality of stacked structures. Each stacked structure comprises a laminated In-doped beta-Ga2O3 layer, an N-type doped beta-Ga2O3 layer and an undoped beta-Ga2O3 layer. The Ga source of at least one of the In-doped beta-Ga2O3 layer, the N-type doped beta-Ga2O3 layer and the undoped beta-Ga2O3 layer comprises TMGa, and the Ga source of at least one layer comprises TEGa. The application can obtain a beta-Ga2O3 epitaxial structure with a certain thickness, improve the crystal quality, growth rate and mobility of the beta-Ga2O3 epitaxial structure, and reduce the roughness and background carrier concentration of the beta-Ga2O3 epitaxial structure.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically to a β-Ga2O3 epitaxial structure and its manufacturing method. Background Technology

[0002] Materials with wider bandgap naturally possess greater resistance to high temperatures, radiation, and high voltages, as well as lower on-resistance. Ga2O3, as a novel ultrawide semiconductor material, boasts an ultrawide bandgap of 4.9 eV, exhibits excellent voltage withstand capability, and possesses an on-resistance of 8 mV·cm⁻¹. -1 With a theoretical field strength of 3444 and a Baliga figure of merit of 3444, devices fabricated using Ga2O3 (i.e., Ga2O3-based devices) exhibit better conduction characteristics, and Ga2O3 materials have broad application prospects in the field of ultra-high voltage power electronic devices.

[0003] Among them, β-Ga₂O₃ with a monoclinic phase is the most stable thermodynamic crystal structure. To realize the application of β-Ga₂O₃ in ultra-high voltage power electronic devices, it is necessary to epitaxially prepare thick epitaxial films (e.g., with a thickness exceeding 10 μm) with high crystal quality on a substrate. Simultaneously, these epitaxial films must also possess low background carrier concentration (including impurities introduced by unintentional doping and intentionally introduced but unactivated impurities) and high mobility. However, the β-Ga₂O₃ epitaxial thick film structures in related technologies suffer from slow growth rates, high background carrier concentrations and low mobility, poor crystal quality, and large roughness.

[0004] Therefore, improvements are needed to at least partially address the aforementioned problems. Summary of the Invention

[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0006] To at least partially solve the above-mentioned technical problems, this application provides a β-Ga2O3 epitaxial structure, comprising:

[0007] Substrate;

[0008] A β-Ga2O3 epitaxial layer is located on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures. Each stacked structure includes stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. The Ga source of at least one of the In-doped β-Ga2O3 layers, the N-type doped β-Ga2O3 layers, and the undoped β-Ga2O3 layers includes TMGa, and the Ga source of at least one of the layers includes TEGa.

[0009] For example, the bottom layer in each of the stacked structures is the In-doped β-Ga2O3 layer.

[0010] For example, each of the stacked structures includes, from bottom to top, the In-doped β-Ga2O3 layer, the N-type doped β-Ga2O3 layer, and the undoped β-Ga2O3 layer.

[0011] For example, the undoped β-Ga2O3 layer includes a first sub-undoped β-Ga2O3 layer and a second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top, and each of the stacked structures includes the In-doped β-Ga2O3 layer, the N-type doped β-Ga2O3 layer, the first sub-undoped β-Ga2O3 layer and the second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top;

[0012] The In-doped β-Ga2O3 layer is formed at the first temperature, and the Ga source of the In-doped β-Ga2O3 layer is TEGa.

[0013] The N-type doped β-Ga2O3 layer is formed during the heating process from the first temperature to the second temperature, and the Ga source of the N-type doped β-Ga2O3 layer is TMGa;

[0014] The first undoped β-Ga2O3 layer is formed at the second temperature, and the Ga source of the first undoped β-Ga2O3 layer is TMGa.

[0015] The second undoped β-Ga2O3 layer is formed during the cooling process from the second temperature to the first temperature, and the Ga source of the second undoped β-Ga2O3 layer is TMGa and TEGa.

[0016] For example, the N-type doping element in the N-type doped β-Ga2O3 layer includes Si, Sn or Ge.

[0017] This application also provides a method for manufacturing a β-Ga2O3 epitaxial structure, comprising:

[0018] Provide substrate;

[0019] A β-Ga2O3 epitaxial layer is formed on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures. Each stacked structure includes stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. The Ga source of at least one of the In-doped β-Ga2O3 layers, the N-type doped β-Ga2O3 layers, and the undoped β-Ga2O3 layers includes TMGa, and the Ga source of at least one of the layers includes TEGa.

[0020] For example, the undoped β-Ga2O3 layer includes a first sub-undoped β-Ga2O3 layer and a second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top, and each of the stacked structures includes the In-doped β-Ga2O3 layer, the N-type doped β-Ga2O3 layer, the first sub-undoped β-Ga2O3 layer and the second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top;

[0021] The In-doped β-Ga2O3 layer is formed at the first temperature, and the Ga source of the In-doped β-Ga2O3 layer is TEGa.

[0022] The N-type doped β-Ga2O3 layer is formed during the heating process from the first temperature to the second temperature, and the Ga source of the N-type doped β-Ga2O3 layer is TMGa;

[0023] The first undoped β-Ga2O3 layer is formed at the second temperature, and the Ga source of the first undoped β-Ga2O3 layer is TMGa.

[0024] The second undoped β-Ga2O3 layer is formed during the cooling process from the second temperature to the first temperature, and the Ga source of the second undoped β-Ga2O3 layer is TMGa and TEGa.

[0025] For example, the first temperature ranges from 700°C to 830°C, and the second temperature ranges from 900°C to 1000°C.

[0026] For example, when forming the In-doped β-Ga2O3 layer, the flow rate of TEGa is 700 sccm-1000 sccm;

[0027] When forming the N-type doped β-Ga2O3 layer, the flow rate of TMGa is 500 sccm-800 sccm;

[0028] When forming the first undoped β-Ga2O3 layer, the flow rate of TMGa is 500 sccm-800 sccm;

[0029] When forming the second undoped β-Ga2O3 layer, the flow rate of TMGa is 80 sccm-200 sccm, and the flow rate of TEGa is 400 sccm-700 sccm.

[0030] For example, the In-doped β-Ga2O3 layer is formed under a first pressure and a first VI / III ratio, and the In-doped β-Ga2O3 layer has a first thickness, wherein the first pressure ranges from 15 mbar to 50 mbar, the first VI / III ratio ranges from 180 to 320, and the first thickness ranges from 10 nm to 16 nm.

[0031] The N-type doped β-Ga2O3 layer is formed under a second pressure and a second VI / III ratio, and the N-type doped β-Ga2O3 layer has a second thickness, wherein the second pressure ranges from 40 mbar to 70 mbar, the second VI / III ratio ranges from 320 to 520, and the second thickness ranges from 8 nm to 12 nm.

[0032] The first undoped β-Ga2O3 layer is formed under a third pressure and a third VI / III ratio, and the first undoped β-Ga2O3 layer has a third thickness, wherein the third pressure ranges from 40 mbar to 70 mbar, the third VI / III ratio ranges from 320 to 520, and the third thickness ranges from 4 nm to 8 nm.

[0033] The second sub-undoped β-Ga2O3 layer is formed under a fourth pressure and a fourth VI / III ratio, and the second sub-undoped β-Ga2O3 layer has a fourth thickness, wherein the fourth pressure ranges from 20 mbar to 50 mbar, the fourth VI / III ratio ranges from 240 to 420, and the fourth thickness ranges from 1 nm to 4 nm.

[0034] The β-Ga2O3 epitaxial structure and its manufacturing method disclosed in this application include a β-Ga2O3 epitaxial layer comprising multiple stacked structures. Each stacked structure includes stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. At least one of the In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers contains a Ga source of TMGa, and at least one Ga source contains a Ga source of TEGa. This method can improve the crystal quality, growth rate, and mobility of the β-Ga2O3 epitaxial structure while obtaining a β-Ga2O3 epitaxial structure with a certain thickness, and reduce the roughness and background carrier concentration of the β-Ga2O3 epitaxial structure. Attached Figure Description

[0035] The following drawings, which are incorporated herein by reference and are used to understand this application, illustrate embodiments of the invention and their descriptions to explain the principles of the invention.

[0036] In the attached image:

[0037] Figure 1 A cross-sectional schematic diagram of a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application is shown;

[0038] Figure 2 A flowchart illustrating a method for manufacturing a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application is shown;

[0039] Figure 3 The diagram shows the relationship between growth time and temperature of a β-Ga2O3 epitaxial layer according to an exemplary embodiment of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 10 - Substrate, 11 - β-Ga2O3 epitaxial layer, 110 - Stacked structure, 111 - In-doped β-Ga2O3 layer, 112 - N-type doped β-Ga2O3 layer, 113 - Undoped β-Ga2O3 layer, 1131 - First sub-undoped β-Ga2O3 layer, 1132 - Second sub-undoped β-Ga2O3 layer. Detailed Implementation

[0042] The present application will now be described more fully with reference to the accompanying drawings, in which embodiments of the present application are illustrated. However, the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present application to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0043] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0044] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0046] Embodiments of the application are described herein with reference to cross-sectional views illustrating ideal embodiments (and intermediate structures). Thus, variations from the shapes shown can be anticipated due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the application should not be limited to the specific shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing processes. For example, implantation regions shown as rectangular typically have rounded or curved features at their edges and / or implantation concentration gradients, rather than a binary change from implantation regions to non-implantation regions. Similarly, buried regions formed by implantation can result in some implantation in the region between the buried region and the surface traversed during implantation. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to show the actual shapes of the regions of the device and are not intended to limit the scope of the application.

[0047] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms as defined in commonly used dictionaries shall be construed as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and not as interpreted in an ideal or overly formal sense, unless expressly defined herein.

[0048] To fully understand this application, a detailed structure will be presented in the following description to illustrate the technical solutions proposed in this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0049] In related technologies, metal-organic chemical vapor deposition (MOCVD) is generally used to epitaxially grow β-Ga2O3 epitaxial structures. However, current MOCVD epitaxial growth of β-Ga2O3 epitaxial structures suffers from problems such as slow growth rate, high background carrier concentration and low mobility, poor crystal quality and large roughness.

[0050] In related technologies, the growth rate of β-Ga2O3 epitaxial structures, the background carrier concentration, and the mobility are generally improved by controlling the parameters of the metal-organic source (Mo source) and performing continuous N-type doping. However, simply controlling the parameters of the Mo source cannot simultaneously address the issues of background carrier concentration, mobility, film thickness, and crystal quality. On the other hand, continuous N-type doping will increase the background carrier concentration in the β-Ga2O3 epitaxial structure, making it impossible to achieve low mobility (N-type doping is intentional doping, and continuous N-type doping will result in an excessively high concentration of introduced N-type dopants. Some of these N-type dopants will not be activated, which will instead lead to an increase in the background carrier concentration. The unactivated N-type dopants will block the migration channels, thereby causing a decrease in mobility).

[0051] Therefore, in view of the aforementioned technical problems, this application proposes a β-Ga2O3 epitaxial structure, comprising:

[0052] Substrate;

[0053] A β-Ga2O3 epitaxial layer is located on a substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures. Each stacked structure includes stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. The Ga source of at least one of the In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers includes TMGa, and the Ga source of at least one of the layers includes TEGa.

[0054] The β-Ga2O3 epitaxial structure of this application includes multiple stacked structures, each stacked structure including stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. At least one of the In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers has a Ga source including TMGa, and at least one of the Ga sources includes TEGa. This structure can improve the crystal quality, growth rate, and mobility of the β-Ga2O3 epitaxial structure while reducing the roughness and background carrier concentration of the β-Ga2O3 epitaxial structure, while obtaining a β-Ga2O3 epitaxial structure with a certain thickness.

[0055] Example 1

[0056] Below, for reference Figure 1 and Figure 2 The β-Ga2O3 epitaxial structure in the embodiments of this application is described. Figure 1 A cross-sectional schematic diagram of a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application is shown.

[0057] In one example, such as Figure 1As shown, the β-Ga2O3 epitaxial structure of this application includes a substrate 10 and a β-Ga2O3 epitaxial layer 11 located on the substrate 10. The β-Ga2O3 epitaxial layer 11 includes multiple stacked structures 110. Each stacked structure 110 includes stacked In-doped β-Ga2O3 layers 111, N-type doped β-Ga2O3 layers 112, and undoped β-Ga2O3 layers 113. At least one of the In-doped β-Ga2O3 layers 111, N-type doped β-Ga2O3 layers 112, and undoped β-Ga2O3 layers 113 contains a Ga source including TMGa (trimethylgallium) and at least one contains a Ga source including TEGa (triethylgallium). Exemplarily, the β-Ga2O3 epitaxial layer 11 of this application may also be referred to as an HT-Ga2O3 (High Temperature-Ga2O3) epitaxial layer.

[0058] In one example, the substrate 10 includes a Sn-doped β-Ga2O3 substrate. Specifically, the substrate 10 can be a Sn-doped (100), (010), (001) or (-201) plane Ga2O3 substrate. The β-Ga2O3 epitaxial structure of this application is a homogeneous epitaxial structure.

[0059] In one example, the formation order of the In-doped β-Ga₂O₃ layer 111, the N-type doped β-Ga₂O₃ layer 112, and the undoped β-Ga₂O₃ layer 113 in each stacked structure 110 is not specifically limited. Taking bottom-up epitaxial growth as an example, the stacked structure 110 may include bottom-up In-doped β-Ga₂O₃ layer 111, N-type doped β-Ga₂O₃ layer 112, and the undoped β-Ga₂O₃ layer 113; or, the stacked structure 110 may include bottom-up In-doped β-Ga₂O₃ layer 111, the undoped β-Ga₂O₃ layer 113, and the N-type doped β-Ga₂O₃ layer 112; or, the stacked structure 110 may include bottom-up N-type doped β-Ga₂O₃ layer 112. The stacked structure 110 may include, from bottom to top, an N-type doped β-Ga2O3 layer 112, an In-doped β-Ga2O3 layer 111, and an In-doped β-Ga2O3 layer 113; or, the stacked structure 110 may include, from bottom to top, an N-type doped β-Ga2O3 layer 112, an In-doped β-Ga2O3 layer 113, and an In-doped β-Ga2O3 layer 111; or, the stacked structure 110 may include, from bottom to top, an In-doped β-Ga2O3 layer 113, an In-doped β-Ga2O3 layer 111, and an N-type doped β-Ga2O3 layer 112; or, the stacked structure 110 may include, from bottom to top, an undoped β-Ga2O3 layer 113, an N-type doped β-Ga2O3 layer 112, and an In-doped β-Ga2O3 layer 111. For example, each stacked structure 110 may also include multiple layers of In-doped β-Ga2O3 layers 111, multiple layers of N-type doped β-Ga2O3 layers 112, and multiple layers of undoped β-Ga2O3 layers 113, which is not limited in this application.

[0060] In one example, during the epitaxial growth of β-Ga2O3, the anisotropy of surface energy and atomic diffusion ability, as well as the competition between the film growth and etching reactions (Ga2O desorption), lead to step coalescence and trench undulation problems, resulting in significant surface undulations and a sharp increase in surface roughness of the β-Ga2O3 epitaxial layer. The β-Ga2O3 epitaxial layer 11 of this application includes an In-doped β-Ga2O3 layer 111. The In doping in the In-doped β-Ga2O3 layer 111 can suppress the formation and desorption of Ga2O during epitaxial growth and enhance the adsorption capacity of Ga atoms on the surface, optimizing the β-Ga2O3 growth process. The co-adsorption of Ga atoms and In atoms can promote the transformation of the epitaxial film growth mode from an island-like growth mode to a step-flow growth mode, stabilizing surface thermal fluctuations during epitaxial film growth, suppressing trench morphology, effectively solving the problems of step coalescence and trench undulation, reducing surface roughness, and increasing the growth rate.

[0061] In one example, the β-Ga₂O₃ epitaxial layer 11 of this application includes an N-type doped β-Ga₂O₃ layer 112. The N-type dopant element in the N-type doped β-Ga₂O₃ layer 112 can introduce free electrons, thereby improving mobility. Exemplarily, the N-type dopant element in the N-type doped β-Ga₂O₃ layer 112 includes Si, Sn, or Ge, or it can be any other suitable N-type dopant element, which is not limited in this application.

[0062] In one example, the β-Ga2O3 epitaxial layer 11 of this application includes an undoped β-Ga2O3 layer 113. The undoped β-Ga2O3 layer 113 can achieve thick film growth and adjust the proportion of In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112 in the entire β-Ga2O3 epitaxial layer 11. The β-Ga2O3 epitaxial layer 11 in this application has multiple stacked structures to achieve epitaxial growth of β-Ga2O3 epitaxial layer 11 with a certain thickness (e.g., epitaxial growth of β-Ga2O3 epitaxial layer 11 with a thickness exceeding 10 μm). However, if each stacked structure only includes In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112, and does not include the undoped β-Ga2O3 layer 113, it will lead to the In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112 being undoped. The thickness of the 3-layer 112 is too thick, meaning that the In doping time and N-type doping time are too long. The excessive In doping time will lead to an increase in the In concentration in the epitaxial layer, resulting in the growth of an InGaO structure instead of the designed β-Ga2O3 structure. The excessive N-type doping time will lead to an excessively high N-type dopant concentration. When the N-type dopant concentration is too high, some of the N-type dopant elements will not be activated, which will instead lead to an increase in the background carrier concentration. Furthermore, the unactivated N-type dopant elements will block the migration channels, thereby leading to a decrease in mobility. Therefore, by including an undoped β-Ga2O3 layer 113 in the β-Ga2O3 epitaxial layer 11, this application can achieve thick film growth while simultaneously controlling the proportion of In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112 in the entire β-Ga2O3 epitaxial layer 11 using the undoped β-Ga2O3 layer 113. This enables pulsed In doping and N-type doping, avoiding the problem of InGaO structure growth due to excessively long In doping time, and also avoiding the problem of increased background carrier concentration and decreased mobility due to excessively long N-type doping time.

[0063] In one example, an In-doped β-Ga2O3 layer 111, an N-type doped β-Ga2O3 layer 112, and an undoped β-Ga2O3 layer 113 are grown alternately. The resulting grain boundaries can effectively prevent defects from extending inside the β-Ga2O3 epitaxial layer 11, thereby improving the crystal quality of the β-Ga2O3 epitaxial layer 11.

[0064] In one example, by making the β-Ga2O3 epitaxial layer 11 include multiple stacked structures, and each stacked structure includes stacked In-doped β-Ga2O3 layers 111, N-type doped β-Ga2O3 layers 112 and undoped β-Ga2O3 layers 113, it is possible to obtain a β-Ga2O3 epitaxial structure with a certain thickness, while improving the crystal quality and mobility of the β-Ga2O3 epitaxial structure and reducing the roughness of the β-Ga2O3 epitaxial structure.

[0065] In one example, the Ga source for at least one of the In-doped β-Ga₂O₃ layer 111, the N-type doped β-Ga₂O₃ layer 112, and the undoped β-Ga₂O₃ layer 113 includes TMGa. Compared to TEGa, TMGa has a higher vapor pressure, which means that TMGa is more likely to volatilize and enter the gas phase. At the same time, the higher vapor pressure allows TMGa to be rapidly transported to the film surface by the carrier gas, thereby increasing the growth rate. In addition, compared to TEGa, TMGa also has a higher reaction driving force, that is, the chemical reaction driving force between TMGa and other reactive gases (such as O₂ as an O source) is stronger, which can rapidly decompose and participate in epitaxial growth, thus also improving the growth rate.

[0066] In one example, at least one of the In-doped β-Ga₂O₃ layers 111, N-type doped β-Ga₂O₃ layers 112, and undoped β-Ga₂O₃ layers 113 contains TEGa as the Ga source. During epitaxial growth, whether TMGa or TEGa is used as the Ga source, C impurities are introduced. These C impurities are unintentionally introduced impurities and belong to the background carriers. When TEGa is used as the Ga source, the organic ethyl groups in TEGa can reduce the C impurity concentration through β-hydride elimination reactions, thereby reducing the background carrier concentration. The background carrier concentration can be controlled on an order of magnitude. Specifically, TEGa can generate ethylene gas through β-hydride elimination reactions. Ethylene gas is a volatile gas that can be easily discharged, thereby reducing the C impurity concentration. At the same time, the reduction of C impurity concentration can also improve the crystal quality.

[0067] In one example, the Ga source of at least one of the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, and the undoped β-Ga2O3 layer 113 includes TMGa and the Ga source of at least one layer includes TEGa. It is not limited to the fact that the Ga source of a single film layer in this application must be either TMGa or TEGa. The Ga source of a single film layer in this application can also be a mixed Ga source including TMGa and TEGa. For example, when forming the undoped β-Ga2O3 layer 113, the Ga source can be a mixed Ga source including TMGa and TEGa.

[0068] In one example, by making at least one of the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, and the undoped β-Ga2O3 layer 113 have Ga sources including TMGa and at least one of the Ga sources including TEGa, and by reasonably setting the flow rate and flow time of TMGa and TEGa in the Ga source, the background carrier concentration can be controlled on the order of magnitude, while ensuring the growth rate. That is, it is possible to reduce the background carrier concentration of the β-Ga2O3 epitaxial structure while improving the crystal quality and growth rate of the β-Ga2O3 epitaxial layer 11.

[0069] In one example, the number of stacked structures 110 is greater than or equal to 80 to obtain a β-Ga2O3 epitaxial layer 11 with a certain thickness, for example, obtaining a β-Ga2O3 epitaxial layer 11 with a thickness greater than 10 μm. Exemplarily, the number of stacked structures 110 is also less than or equal to 320 to prevent excessively long growth time.

[0070] In one example, the bottom layer in each stacked structure 110 is an In-doped β-Ga2O3 layer 111. That is, the In-doped β-Ga2O3 layer 111 is grown epitaxially first, followed by the epitaxial growth of an N-type doped β-Ga2O3 layer 112 and an undoped β-Ga2O3 layer 113. By growing the In-doped β-Ga2O3 layer 111 first, the growth process can be optimized from the beginning, promoting the transformation of the epitaxial film growth mode from an island-like growth mode to a step-flow growth mode. This is equivalent to having a good "foundation", which enables the N-type doped β-Ga2O3 layer 112 and the undoped β-Ga2O3 layer 113 obtained by continuing epitaxial growth on the In-doped β-Ga2O3 layer 111 to have higher crystal quality.

[0071] In one example, each stacked structure 110 includes, from bottom to top, an In-doped β-Ga₂O₃ layer 111, an N-type doped β-Ga₂O₃ layer 112, and an undoped β-Ga₂O₃ layer 113, which are epitaxially grown sequentially. After epitaxially growing the N-type doped β-Ga₂O₃ layer 112, the N-type dopant source is turned off, and the undoped β-Ga₂O₃ layer 113 is grown. This allows sufficient diffusion time for the N-type dopant element, thereby reducing lattice stress and further improving crystal quality.

[0072] In one example, the undoped β-Ga2O3 layer 113 includes a first sub-undoped β-Ga2O3 layer 1131 and a second sub-undoped β-Ga2O3 layer 1132 stacked from bottom to top. Each stacked structure 110 includes an In-doped β-Ga2O3 layer 111, an N-doped β-Ga2O3 layer 112, a first sub-undoped β-Ga2O3 layer 1131 and a second sub-undoped β-Ga2O3 layer 1132 stacked from bottom to top. In this process, an In-doped β-Ga₂O₃ layer 111 is formed at a first temperature, with TEGa as the Ga source; an N-type doped β-Ga₂O₃ layer 112 is formed during a temperature rise from the first temperature to a second temperature, with TMGa as the Ga source; a first undoped β-Ga₂O₃ layer 1131 is formed at a second temperature, with TMGa as the Ga source; and a second undoped β-Ga₂O₃ layer 1132 is formed during a temperature drop from the second temperature to the first temperature, with both TMGa and TEGa as Ga sources. Exemplarily, the first temperature ranges from 700℃ to 830℃, and the second temperature ranges from 900℃ to 1000℃; preferably, the first temperature is 800℃, and the second temperature is 950℃. In one example, an In-doped β-Ga2O3 layer 111 is formed at a first temperature. The Ga source for the In-doped β-Ga2O3 layer 111 is TEGa, which can reduce the background carrier concentration and roughness and improve the crystal quality.

[0073] In one example, the N-type doped β-Ga₂O₃ layer 112 is formed during a heating process from a first temperature to a second temperature. The Ga source for the N-type doped β-Ga₂O₃ layer 112 is TMGa, which can improve the growth rate and mobility. Simultaneously, growing the N-type doped β-Ga₂O₃ layer 112 during the heating process allows more C impurities to be released from the N-type doped β-Ga₂O₃ layer 112, thereby further reducing the background carrier concentration. Furthermore, the higher growth temperature can also reduce the defect density, thus improving the crystal quality. Exemplarily, the heating process from the first temperature to the second temperature is a uniform heating process.

[0074] In one example, the first undoped β-Ga2O3 layer 1131 is formed at a second temperature. The Ga source of the first undoped β-Ga2O3 layer 1131 is TMGa. During the growth of the first undoped β-Ga2O3 layer 1131, the N-type doping source is turned off, which can give the N-type doping source sufficient diffusion time, thereby reducing lattice stress and further improving crystal quality. At the same time, the higher growth temperature can also reduce defect density, thereby improving crystal quality.

[0075] In one example, the second undoped β-Ga₂O₃ layer 1132 is formed during the cooling process from the second temperature to the first temperature. The Ga source for the second undoped β-Ga₂O₃ layer 1132 is TMGa and TEGa. The temperature returns to the first temperature, forming a temperature cycle. This cycle connects with the In-doped β-Ga₂O₃ layer 111 in the next stacked structure, forming a transition and facilitating the growth of the next stacked structure. Simultaneously, the Ga source for the N-type doped β-Ga₂O₃ layer 112 is TMGa, and the In-doped β-Ga₂O₃ layer... The Ga source for layer 111 is TEGa. By using TMGa and TEGa as the Ga source for the second undoped β-Ga2O3 layer 1132, a transition and connection can be achieved in the supply of Ga source, which is beneficial for the growth of the In-doped β-Ga2O3 layer 111 in the next stacked structure. Simultaneously, using TMGa and TEGa as the Ga source for the second undoped β-Ga2O3 layer 1132 allows for the control of both background carrier concentration and growth rate, ensuring crystal quality while providing a connection for the order-of-magnitude control of background carrier concentration. Exemplarily, during the growth of the second undoped β-Ga2O3 layer 1132, the supply of TEGa in the Ga source is greater than the supply of TMGa. Exemplarily, the cooling process from the second temperature to the first temperature is a uniform cooling process. Exemplarily, the time taken for the cooling process from the second temperature to the first temperature is less than the time taken for the heating process from the first temperature to the second temperature.

[0076] In one example, an In-doped β-Ga2O3 layer 111, an N-type doped β-Ga2O3 layer 112, a first undoped β-Ga2O3 layer 1131, and a second undoped β-Ga2O3 layer 1132 are grown alternately. The resulting grain boundaries can effectively prevent defects from extending inside the β-Ga2O3 epitaxial layer 11, thereby improving the crystal quality of the β-Ga2O3 epitaxial layer 11.

[0077] In one example, the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, the first undoped β-Ga2O3 layer 1131, and the second undoped β-Ga2O3 layer 1132 can also be formed in other orders. Similarly, the growth temperature settings of the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, the first undoped β-Ga2O3 layer 1131, and the second undoped β-Ga2O3 layer 1132, as well as the supply and distribution of the Ga source, are not limited to the embodiments described above, and this application does not impose any restrictions on them.

[0078] In summary, the β-Ga2O3 epitaxial structure of this application comprises multiple stacked structures, each stacked structure including stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. At least one of the In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers has a Ga source including TMGa, and at least one of the Ga sources includes TEGa. This structure can improve the crystal quality, growth rate, and mobility of the β-Ga2O3 epitaxial structure while reducing the roughness and background carrier concentration of the β-Ga2O3 epitaxial structure, while obtaining a β-Ga2O3 epitaxial structure with a certain thickness.

[0079] Example 2

[0080] In another embodiment of this application, a method for manufacturing a β-Ga2O3 epitaxial structure is provided, the method being used to manufacture the β-Ga2O3 epitaxial structure described in Embodiment 1.

[0081] The following reference Figure 1 , Figure 2 as well as Figure 3 The present application describes a method for manufacturing a β-Ga2O3 epitaxial structure, wherein... Figure 1 This paper shows a schematic cross-sectional view of a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application. Figure 2 A flowchart illustrating a method for manufacturing a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application is shown. Figure 3 The diagram shows the relationship between growth time and temperature of a β-Ga2O3 epitaxial layer according to an exemplary embodiment of this application.

[0082] Exemplarily, the method for manufacturing the β-Ga2O3 epitaxial structure of this application includes the following steps:

[0083] First, step S1 is performed to provide substrate 10.

[0084] In one example, the substrate 10 includes a Sn-doped β-Ga2O3 substrate. Specifically, the substrate 10 can be a Sn-doped (100), (010), (001) or (-201) plane Ga2O3 substrate. The β-Ga2O3 epitaxial structure of this application is a homogeneous epitaxial structure.

[0085] Next, step S2 is performed to form a β-Ga2O3 epitaxial layer 11 on the substrate 10. The β-Ga2O3 epitaxial layer 11 includes multiple stacked structures 110. Each stacked structure 110 includes stacked In-doped β-Ga2O3 layers 111, N-type doped β-Ga2O3 layers 112, and undoped β-Ga2O3 layers 113. At least one of the In-doped β-Ga2O3 layers 111, N-type doped β-Ga2O3 layers 112, and undoped β-Ga2O3 layers 113 has a Ga source comprising TMGa (trimethylgallium) and at least one has a Ga source comprising TEGa (triethylgallium). Exemplarily, the β-Ga2O3 epitaxial layer 11 of this application may also be referred to as an HT-Ga2O3 (High Temperature-Ga2O3) epitaxial layer. Exemplarily, the In source of the In-doped β-Ga2O3 layer 111 is TMI (trimethylindium).

[0086] In one example, a β-Ga2O3 epitaxial layer 11 is grown in an MOCVD reaction chamber. More specifically, an In-doped β-Ga2O3 layer 111, an N-type doped β-Ga2O3 layer 112, and an undoped β-Ga2O3 layer 113 are grown in an MOCVD reaction chamber.

[0087] In one example, before forming the β-Ga2O3 epitaxial layer 11, the substrate 10 is subjected to annealing and desorption treatment. Taking the substrate 10 as a Sn-doped (001) Ga2O3 substrate as an example, the annealing and desorption treatment of the substrate 10 includes: placing the substrate 10 in the MOCVD reaction chamber, treating the substrate 10 in an oxygen atmosphere for 5 min-20 min, and controlling the temperature at 800℃-1000℃ for high-temperature in-situ annealing pretreatment; then, maintaining the temperature at 800℃-1000℃, the pressure at 100mbar-200mbar, and the time for 3 min-10 min for desorption treatment of the substrate 10 to remove impurities and organic contaminants on the surface of the substrate 10.

[0088] In one example, the formation order of the In-doped β-Ga₂O₃ layer 111, the N-type doped β-Ga₂O₃ layer 112, and the undoped β-Ga₂O₃ layer 113 in each stacked structure 110 is not specifically limited. Taking bottom-up epitaxial growth as an example, the stacked structure 110 may include bottom-up In-doped β-Ga₂O₃ layer 111, N-type doped β-Ga₂O₃ layer 112, and the undoped β-Ga₂O₃ layer 113; or, the stacked structure 110 may include bottom-up In-doped β-Ga₂O₃ layer 111, the undoped β-Ga₂O₃ layer 113, and the N-type doped β-Ga₂O₃ layer 112; or, the stacked structure 110 may include bottom-up N-type doped β-Ga₂O₃ layer 112. The stacked structure 110 may include, from bottom to top, an N-type doped β-Ga2O3 layer 112, an In-doped β-Ga2O3 layer 111, and an In-doped β-Ga2O3 layer 113; or, the stacked structure 110 may include, from bottom to top, an N-type doped β-Ga2O3 layer 112, an In-doped β-Ga2O3 layer 113, and an In-doped β-Ga2O3 layer 111; or, the stacked structure 110 may include, from bottom to top, an In-doped β-Ga2O3 layer 113, an In-doped β-Ga2O3 layer 111, and an N-type doped β-Ga2O3 layer 112; or, the stacked structure 110 may include, from bottom to top, an undoped β-Ga2O3 layer 113, an N-type doped β-Ga2O3 layer 112, and an In-doped β-Ga2O3 layer 111. For example, each stacked structure 110 may also include multiple layers of In-doped β-Ga2O3 layers 111, multiple layers of N-type doped β-Ga2O3 layers 112, and multiple layers of undoped β-Ga2O3 layers 113, which is not limited in this application.

[0089] In one example, during the epitaxial growth of β-Ga2O3, the anisotropy of surface energy and atomic diffusion ability, as well as the competition between the film growth and etching reactions (Ga2O desorption), lead to step coalescence and trench undulation problems, resulting in significant surface undulations and a sharp increase in surface roughness of the β-Ga2O3 epitaxial layer. The β-Ga2O3 epitaxial layer 11 of this application includes an In-doped β-Ga2O3 layer 111. The In doping in the In-doped β-Ga2O3 layer 111 can suppress the formation and desorption of Ga2O during epitaxial growth and enhance the adsorption capacity of Ga atoms on the surface, optimizing the β-Ga2O3 growth process. The co-adsorption of Ga atoms and In atoms can promote the transformation of the epitaxial film growth mode from an island-like growth mode to a step-flow growth mode, stabilizing surface thermal fluctuations during epitaxial film growth, suppressing trench morphology, effectively solving the problems of step coalescence and trench undulation, reducing surface roughness, and increasing the growth rate.

[0090] In one example, the β-Ga₂O₃ epitaxial layer 11 of this application includes an N-type doped β-Ga₂O₃ layer 112. The N-type dopant element in the N-type doped β-Ga₂O₃ layer 112 can introduce free electrons, thereby improving mobility. Exemplarily, the N-type dopant element in the N-type doped β-Ga₂O₃ layer 112 includes Si, Sn, or Ge, or it can be any other suitable N-type dopant element, which is not limited in this application.

[0091] In one example, the β-Ga2O3 epitaxial layer 11 of this application includes an undoped β-Ga2O3 layer 113. The undoped β-Ga2O3 layer 113 can achieve thick film growth and adjust the proportion of In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112 in the entire β-Ga2O3 epitaxial layer 11. The β-Ga2O3 epitaxial layer 11 in this application has multiple stacked structures to achieve epitaxial growth of β-Ga2O3 epitaxial layer 11 with a certain thickness (e.g., epitaxial growth of β-Ga2O3 epitaxial layer 11 with a thickness exceeding 10 μm). However, if each stacked structure only includes In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112, and does not include the undoped β-Ga2O3 layer 113, it will lead to the In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112 being undoped. The thickness of the 3-layer 112 is too thick, meaning that the In doping time and N-type doping time are too long. The excessive In doping time will lead to an increase in the In concentration in the epitaxial layer, resulting in the growth of an InGaO structure instead of the designed β-Ga2O3 structure. The excessive N-type doping time will lead to an excessively high N-type dopant concentration. When the N-type dopant concentration is too high, some of the N-type dopant elements will not be activated, which will instead lead to an increase in the background carrier concentration. Furthermore, the unactivated N-type dopant elements will block the migration channels, thereby leading to a decrease in mobility. Therefore, by including an undoped β-Ga2O3 layer 113 in the β-Ga2O3 epitaxial layer 11, the proportions of In-doped β-Ga2O3 layer 111 and N-type doped β-Ga2O3 layer 112 in the entire β-Ga2O3 epitaxial layer 11 can be controlled and adjusted using the undoped β-Ga2O3 layer 113 while achieving thick film growth. This enables pulsed In doping and N-type doping, avoiding the problem of InGaO structure growth due to excessively long In doping time, and avoiding the problem of increased background carrier concentration and decreased mobility due to excessively long N-type doping time.

[0092] In one example, an In-doped β-Ga2O3 layer 111, an N-type doped β-Ga2O3 layer 112, and an undoped β-Ga2O3 layer 113 are grown alternately. The resulting grain boundaries can effectively prevent defects from extending inside the β-Ga2O3 epitaxial layer 11, thereby improving the crystal quality of the β-Ga2O3 epitaxial layer 11.

[0093] In one example, by making the β-Ga2O3 epitaxial layer 11 include multiple stacked structures, and each stacked structure includes stacked In-doped β-Ga2O3 layers 111, N-type doped β-Ga2O3 layers 112 and undoped β-Ga2O3 layers 113, it is possible to obtain a β-Ga2O3 epitaxial structure with a certain thickness, while improving the crystal quality and mobility of the β-Ga2O3 epitaxial structure and reducing the roughness of the β-Ga2O3 epitaxial structure.

[0094] In one example, the Ga source for at least one of the In-doped β-Ga₂O₃ layer 111, the N-type doped β-Ga₂O₃ layer 112, and the undoped β-Ga₂O₃ layer 113 includes TMGa. Compared to TEGa, TMGa has a higher vapor pressure, which means that TMGa is more likely to volatilize and enter the gas phase. At the same time, the higher vapor pressure allows TMGa to be rapidly transported to the film surface by the carrier gas, thereby increasing the growth rate. In addition, compared to TEGa, TMGa also has a higher reaction driving force, that is, the chemical reaction driving force between TMGa and other reactive gases (such as O₂ as an O source) is stronger, which can rapidly decompose and participate in epitaxial growth, thus also improving the growth rate.

[0095] In one example, at least one of the In-doped β-Ga₂O₃ layers 111, N-type doped β-Ga₂O₃ layers 112, and undoped β-Ga₂O₃ layers 113 contains TEGa as the Ga source. During epitaxial growth, whether TMGa or TEGa is used as the Ga source, C impurities are introduced. These C impurities are unintentionally introduced impurities and belong to the background carriers. When TEGa is used as the Ga source, the organic ethyl groups in TEGa can reduce the C impurity concentration through β-hydride elimination reactions, thereby reducing the background carrier concentration. The background carrier concentration can be controlled on an order of magnitude. Specifically, TEGa can generate ethylene gas through β-hydride elimination reactions. Ethylene gas is a volatile gas that can be easily discharged, thereby reducing the C impurity concentration. At the same time, the reduction of C impurity concentration can also improve the crystal quality.

[0096] In one example, the Ga source of at least one of the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, and the undoped β-Ga2O3 layer 113 includes TMGa and the Ga source of at least one layer includes TEGa. It is not limited to the fact that the Ga source of a single film layer in this application must be either TMGa or TEGa. The Ga source of a single film layer in this application can also be a mixed Ga source including TMGa and TEGa. For example, when forming the undoped β-Ga2O3 layer 113, the Ga source can be a mixed Ga source including TMGa and TEGa.

[0097] In one example, by making at least one of the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, and the undoped β-Ga2O3 layer 113 have Ga sources including TMGa and at least one of the Ga sources including TEGa, and by reasonably setting the flow rate and flow time of TMGa and TEGa in the Ga source, the background carrier concentration can be controlled on the order of magnitude, while ensuring the growth rate. That is, it is possible to reduce the background carrier concentration of the β-Ga2O3 epitaxial structure while improving the crystal quality and growth rate of the β-Ga2O3 epitaxial layer 11.

[0098] In one example, the number of stacked structures 110 is greater than or equal to 80 to obtain a β-Ga2O3 epitaxial layer 11 with a certain thickness, for example, obtaining a β-Ga2O3 epitaxial layer 11 with a thickness greater than 10 μm. Exemplarily, the number of stacked structures 110 is also less than or equal to 320 to prevent excessively long growth time.

[0099] In one example, the bottom layer in each stacked structure 110 is an In-doped β-Ga2O3 layer 111. That is, the In-doped β-Ga2O3 layer 111 is grown epitaxially first, followed by the epitaxial growth of an N-type doped β-Ga2O3 layer 112 and an undoped β-Ga2O3 layer 113. By growing the In-doped β-Ga2O3 layer 111 first, the growth process can be optimized from the beginning, promoting the transformation of the epitaxial film growth mode from an island-like growth mode to a step-flow growth mode. This is equivalent to having a good "foundation", which enables the N-type doped β-Ga2O3 layer 112 and the undoped β-Ga2O3 layer 113 obtained by continuing epitaxial growth on the In-doped β-Ga2O3 layer 111 to have higher crystal quality.

[0100] In one example, each stacked structure 110 includes, from bottom to top, an In-doped β-Ga₂O₃ layer 111, an N-type doped β-Ga₂O₃ layer 112, and an undoped β-Ga₂O₃ layer 113, which are epitaxially grown sequentially. After epitaxially growing the N-type doped β-Ga₂O₃ layer 112, the N-type dopant source is turned off, and the undoped β-Ga₂O₃ layer 113 is grown. This allows sufficient diffusion time for the N-type dopant element, thereby reducing lattice stress and further improving crystal quality.

[0101] In one example, the undoped β-Ga2O3 layer 113 includes a first sub-undoped β-Ga2O3 layer 1131 and a second sub-undoped β-Ga2O3 layer 1132 stacked from bottom to top. Each stacked structure 110 includes an In-doped β-Ga2O3 layer 111, an N-doped β-Ga2O3 layer 112, a first sub-undoped β-Ga2O3 layer 1131 and a second sub-undoped β-Ga2O3 layer 1132 stacked from bottom to top. In this process, an In-doped β-Ga₂O₃ layer 111 is formed at a first temperature, with TEGa as the Ga source. An N-type doped β-Ga₂O₃ layer 112 is formed during a temperature rise from the first temperature to a second temperature, with TMGa as the Ga source. A first undoped β-Ga₂O₃ layer 1131 is formed at a second temperature, with TMGa as the Ga source. A second undoped β-Ga₂O₃ layer 1132 is formed during a temperature drop from the second temperature to the first temperature, with both TMGa and TEGa as Ga sources. For example, during the formation of the second undoped β-Ga₂O₃ layer 1132, the flow rate of TEGa is greater than the flow rate of TMGa.

[0102] In one example, the range of the first temperature is 700℃-830℃, for example, the first temperature can be 700℃, 730℃, 750℃, 770℃, 800℃ or 830℃, and the range of the second temperature is 900℃-1000℃, for example, the second temperature can be 900℃, 930℃, 950℃, 980℃ or 1000℃; preferably, the first temperature is 800℃ and the second temperature is 950℃.

[0103] In one example, taking a first temperature of 800℃ and a second temperature of 950℃ as an example, Figure 3 As shown, in forming a stacked structure in the β-Ga2O3 epitaxial layer 11, an In-doped β-Ga2O3 layer 111 is first formed at 800°C, followed by an N-type doped β-Ga2O3 layer 112 formed during the heating process from 800°C to 950°C, then a first sub-undoped β-Ga2O3 layer 1131 is formed at 950°C, and then a second sub-undoped β-Ga2O3 layer 1132 is formed during the cooling process from 950°C to 800°C.

[0104] In one example, when forming an In-doped β-Ga2O3 layer 111, the flow rate of TEGa is 700 sccm-1000 sccm, for example, the flow rate of TEGa can be 700 sccm, 800 sccm, 900 sccm or 1000 sccm.

[0105] In one example, when forming an N-type doped β-Ga2O3 layer 112, the flow rate of TMGa is 500 sccm-800 sccm, for example, the flow rate of TMGa can be 500 sccm, 600 sccm, 700 sccm or 800 sccm.

[0106] In one example, when forming the first undoped β-Ga2O3 layer 1131, the flow rate of TMGa is 500 sccm-800 sccm, for example, the flow rate of TMGa can be 500 sccm, 600 sccm, 700 sccm or 800 sccm.

[0107] In one example, when forming the second undoped β-Ga2O3 layer 1132, the flow rate of TMGa is 80 sccm-200 sccm, and the flow rate of TEGa is 400 sccm-700 sccm. For example, the flow rate of TMGa can be 80 sccm, 100 sccm, 150 sccm or 200 sccm, and the flow rate of TEGa can be 400 sccm, 500 sccm, 600 sccm or 700 sccm.

[0108] In one example, the In-doped β-Ga₂O₃ layer 111 is formed under a first pressure and a first VI / III ratio (the molar ratio of VI source to III source, which in this embodiment is the molar ratio of O source to Ga source), and the thickness of the In-doped β-Ga₂O₃ layer 111 is a first thickness. The first pressure ranges from 15 mbar to 50 mbar, for example, the first pressure can be 15 mbar, 25 mbar, 30 mbar, 35 mbar, 45 mbar, or 50 mbar; the first VI / III ratio ranges from 180 to 320, for example, the first VI / III ratio can be 180, 200, 250, 280, or 320; and the first thickness ranges from 10 nm to 16 nm, for example, the first thickness can be 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or 16 nm. Preferably, the first pressure is 35 mbar, the first VI / III ratio is 280, and the first thickness is 13 nm.

[0109] In one example, an N-type doped β-Ga₂O₃ layer 112 is formed under a second pressure and a second VI / III ratio, and the thickness of the N-type doped β-Ga₂O₃ layer 112 is a second thickness. The second pressure ranges from 40 mbar to 70 mbar, for example, it can be 40 mbar, 45 mbar, 50 mbar, 55 mbar, 65 mbar, or 70 mbar; the second VI / III ratio ranges from 320 to 520, for example, it can be 320, 350, 380, 450, 500, or 520; and the second thickness ranges from 8 nm to 12 nm, for example, it can be 8 nm, 9 nm, 10 nm, 11 nm, or 12 nm. Preferably, the second pressure is 55 mbar, the second VI / III ratio is 380, and the second thickness is 10 nm.

[0110] In one example, the first undoped β-Ga2O3 layer 1131 is formed under a third pressure and a third VI / III ratio, and the thickness of the first undoped β-Ga2O3 layer 1131 is a third thickness. The third pressure ranges from 40 mbar to 70 mbar, for example, the third pressure can be 40 mbar, 45 mbar, 50 mbar, 55 mbar, 65 mbar, or 70 mbar; the third VI / III ratio ranges from 320 to 520, for example, the third VI / III ratio can be 320, 350, 380, 450, 500, or 520; and the third thickness ranges from 4 nm to 8 nm, for example, the third thickness can be 4 nm, 5 nm, 6 nm, 7 nm, or 8 nm. Preferably, the third pressure is 55 mbar, the third VI / III ratio is 380, and the third thickness is 6 nm.

[0111] In one example, the second undoped β-Ga₂O₃ layer 1132 is formed under a fourth pressure and a fourth VI / III ratio, and the thickness of the second undoped β-Ga₂O₃ layer 1132 is a fourth thickness. The fourth pressure ranges from 20 mbar to 50 mbar, for example, the fourth pressure can be 20 mbar, 30 mbar, 40 mbar, or 50 mbar; the fourth VI / III ratio ranges from 240 to 420, for example, the fourth VI / III ratio can be 240, 300, 320, 350, 400, or 420; and the fourth thickness ranges from 1 nm to 4 nm, for example, the fourth thickness can be 1 nm, 2 nm, 3 nm, or 4 nm. Preferably, the fourth pressure is 40 mbar, the fourth VI / III ratio is 320, and the fourth thickness is 3 nm.

[0112] In one example, an In-doped β-Ga2O3 layer 111 is formed at a first temperature. The Ga source for the In-doped β-Ga2O3 layer 111 is TEGa, which can reduce the background carrier concentration and roughness and improve the crystal quality.

[0113] In one example, the N-type doped β-Ga₂O₃ layer 112 is formed during a heating process from a first temperature to a second temperature. The Ga source for the N-type doped β-Ga₂O₃ layer 112 is TMGa, which can improve the growth rate and mobility. Simultaneously, growing the N-type doped β-Ga₂O₃ layer 112 during the heating process allows more C impurities to be released from the N-type doped β-Ga₂O₃ layer 112, thereby further reducing the background carrier concentration. Furthermore, the higher growth temperature can also reduce the defect density, thus improving the crystal quality. Exemplarily, the heating process from the first temperature to the second temperature is a uniform heating process.

[0114] In one example, the first undoped β-Ga2O3 layer 1131 is formed at a second temperature. The Ga source of the first undoped β-Ga2O3 layer 1131 is TMGa. During the growth of the first undoped β-Ga2O3 layer 1131, the N-type doping source is turned off, which can give the N-type doping source sufficient diffusion time, thereby reducing lattice stress and further improving crystal quality. At the same time, the higher growth temperature can also reduce defect density, thereby improving crystal quality.

[0115] In one example, the second undoped β-Ga₂O₃ layer 1132 is formed during the cooling process from the second temperature to the first temperature. The Ga source for the second undoped β-Ga₂O₃ layer 1132 is TMGa and TEGa. The temperature returns to the first temperature, forming a temperature cycle. This cycle connects with the In-doped β-Ga₂O₃ layer 111 in the next stacked structure, forming a transition and facilitating the growth of the next stacked structure. Simultaneously, the Ga source for the N-type doped β-Ga₂O₃ layer 112 is TMGa, and the In-doped β-Ga₂O₃ layer... The Ga source for layer 111 is TEGa. By using TMGa and TEGa as the Ga source for the second undoped β-Ga2O3 layer 1132, a transition and connection can be achieved in the supply of Ga source, which is beneficial for the growth of the In-doped β-Ga2O3 layer 111 in the next stacked structure. Simultaneously, using TMGa and TEGa as the Ga source for the second undoped β-Ga2O3 layer 1132 allows for the control of both background carrier concentration and growth rate, ensuring crystal quality while providing a connection for the order-of-magnitude control of background carrier concentration. Exemplarily, during the growth of the second undoped β-Ga2O3 layer 1132, the supply of TEGa in the Ga source is greater than the supply of TMGa. Exemplarily, the cooling process from the second temperature to the first temperature is a uniform cooling process. Exemplarily, the time taken for the cooling process from the second temperature to the first temperature is less than the time taken for the heating process from the first temperature to the second temperature.

[0116] In one example, an In-doped β-Ga2O3 layer 111, an N-type doped β-Ga2O3 layer 112, a first undoped β-Ga2O3 layer 1131, and a second undoped β-Ga2O3 layer 1132 are grown alternately. The resulting grain boundaries can effectively prevent defects from extending inside the β-Ga2O3 epitaxial layer 11, thereby improving the crystal quality of the β-Ga2O3 epitaxial layer 11.

[0117] More specifically, the fabrication method of the β-Ga2O3 epitaxial structure of this application will be described in more detail by taking the sequential growth of In-doped β-Ga2O3 layer 111, N-type doped β-Ga2O3 layer 112, first sub-undoped β-Ga2O3 layer 1131 and second sub-undoped β-Ga2O3 layer 1132 in an MOCVD reaction chamber as an example.

[0118] When growing the In-doped β-Ga₂O₃ layer 111, the temperature of the MOCVD reaction chamber is controlled at 700℃-830℃, and the pressure is controlled at 15mbar-50mbar. TEGa is used as the Ga source with a flow rate of 700sccm-1000sccm. High-purity O₂ is used as the O source with a VI / III ratio of 180-320. TMIn is used as the In source with a flow rate of 5sccm-15sccm. N₂ is used as the carrier gas, and the growth thickness of the In-doped β-Ga₂O₃ layer 111 is 10nm-16nm. Preferably, the temperature is 800℃, the pressure is 35mbar, the VI / III ratio is 280, and the growth thickness is 13nm.

[0119] When growing the N-type doped β-Ga₂O₃ layer 112 (taking Si as the N-type dopant as an example), the MOCVD reaction chamber temperature is gradually increased from 700℃-830℃ to 900℃-1000℃, and the MOCVD reaction chamber pressure is controlled at 40mbar-70mbar. TMGa is used as the Ga source with a flow rate of 500sccm-800sccm. High-purity O₂ is used as the O source with a VI / III ratio of 320-520. TEOS (tetraethoxysilane) is used as the Si source with a flow rate of 5sccm-15sccm. N₂ is used as the carrier gas, and the growth thickness of the N-type doped β-Ga₂O₃ layer 112 is 8nm-12nm. Preferably, when growing the N-type doped β-Ga₂O₃ layer 112, the temperature is gradually increased from 800℃ to 950℃, the pressure is 55mbar, the VI / III ratio is 380, and the growth thickness is 10nm.

[0120] When growing the first undoped β-Ga₂O₃ layer 1131, the MOCVD reaction chamber temperature is controlled at 900℃-1000℃, and the MOCVD reaction chamber pressure is controlled at 40mbar-70mbar. TMGa is used as the Ga source, with a flow rate of 500sccm-800sccm. High-purity O₂ is used as the O source, with a VI / III ratio of 320-520. N₂ is used as the carrier gas, and the growth thickness of the first undoped β-Ga₂O₃ layer 1131 is 4nm-8nm. Preferably, the temperature is 950℃, the pressure is 55mbar, the VI / III ratio is 380, and the growth thickness is 6nm.

[0121] When growing the second undoped β-Ga₂O₃ layer 1132, the MOCVD reaction chamber temperature is gradually reduced from 900℃-1000℃ to 700℃-830℃, and the MOCVD reaction chamber pressure is controlled at 20mbar-50mbar. TMGa and TEGa are used simultaneously as Ga sources, with a TMGa flow rate of 80sccm-200sccm and a TEGa flow rate of 400sccm-700sccm. High-purity O₂ is used as the O source, with a VI / III ratio of 320-520. N₂ is used as the carrier gas, and the growth thickness of the second undoped β-Ga₂O₃ layer 1132 is 1nm-4nm. Preferably, when growing the second undoped β-Ga₂O₃ layer 1132, the temperature is gradually reduced from 950℃ to 800℃, the pressure is 40mbar, the VI / III ratio is 320, and the growth thickness is 3nm.

[0122] In one example, the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, the first undoped β-Ga2O3 layer 1131, and the second undoped β-Ga2O3 layer 1132 can also be formed in other orders. Similarly, the growth temperature settings of the In-doped β-Ga2O3 layer 111, the N-type doped β-Ga2O3 layer 112, the first undoped β-Ga2O3 layer 1131, and the second undoped β-Ga2O3 layer 1132, as well as the supply and distribution of the Ga source, are not limited to the embodiments described above, and this application does not impose any restrictions on them.

[0123] In one example, after forming the β-Ga2O3 epitaxial layer 11, a cooling process is included for the β-Ga2O3 epitaxial structure: the carrier gas is oxygen or oxygen plus nitrogen; the MOCVD reaction chamber temperature is controlled at 800℃-1000℃; the pressure is controlled at 20mbar-80mbar; and the duration is 3min-10min. Then, the MOCVD reaction chamber temperature is reduced to below 150℃. This cooling process alleviates the problem of increased roughness in the β-Ga2O3 epitaxial structure due to rapid cooling.

[0124] This concludes the description of the key steps in the manufacturing method of the β-Ga2O3 epitaxial structure of this application. Other steps may also be included in the complete manufacturing of the β-Ga2O3 epitaxial structure, which will not be elaborated here. It is worth mentioning that the order of the above steps can be adjusted without conflict.

[0125] In summary, the method for manufacturing the β-Ga2O3 epitaxial structure of this application includes a β-Ga2O3 epitaxial layer comprising multiple stacked structures. Each stacked structure comprises stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. At least one of the In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers has a Ga source comprising TMGa, and at least one of the Ga sources comprises TEGa. This method can improve the crystal quality, growth rate, and mobility of the β-Ga2O3 epitaxial structure while reducing the roughness and background carrier concentration of the β-Ga2O3 epitaxial structure, while obtaining a β-Ga2O3 epitaxial structure with a certain thickness.

[0126] Although several embodiments have been described herein, it should be understood that many other modifications and embodiments will arise in the mind of those skilled in the art, all of which will fall within the spirit and scope of the concept disclosed herein. More specifically, various modifications and changes may be made in terms of the arrangement and / or components of the subject matter within the scope of this disclosure, the drawings, and the appended claims. In addition to modifications and changes in the components and / or arrangement, the use of alternative methods will also be obvious to those skilled in the art.

Claims

1. A β-Ga₂O₃ epitaxial structure, characterized in that, include: Substrate; A β-Ga2O3 epitaxial layer is located on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures. Each stacked structure includes stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. The Ga source of at least one of the In-doped β-Ga2O3 layers, the N-type doped β-Ga2O3 layers, and the undoped β-Ga2O3 layers includes TMGa, and the Ga source of at least one of the layers includes TEGa.

2. The β-Ga₂O₃ epitaxial structure according to claim 1, characterized in that, The bottom layer in each of the stacked structures is the In-doped β-Ga2O3 layer.

3. The β-Ga₂O₃ epitaxial structure according to claim 1, characterized in that, Each of the stacked structures includes, from bottom to top, the In-doped β-Ga2O3 layer, the N-type doped β-Ga2O3 layer, and the undoped β-Ga2O3 layer.

4. The β-Ga₂O₃ epitaxial structure according to claim 1, characterized in that, The undoped β-Ga2O3 layer includes a first sub-undoped β-Ga2O3 layer and a second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top. Each stacked structure includes an In-doped β-Ga2O3 layer, an N-type doped β-Ga2O3 layer, a first sub-undoped β-Ga2O3 layer and a second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top. The In-doped β-Ga2O3 layer is formed at the first temperature, and the Ga source of the In-doped β-Ga2O3 layer is TEGa. The N-type doped β-Ga2O3 layer is formed during the heating process from the first temperature to the second temperature, and the Ga source of the N-type doped β-Ga2O3 layer is TMGa; The first undoped β-Ga2O3 layer is formed at the second temperature, and the Ga source of the first undoped β-Ga2O3 layer is TMGa. The second undoped β-Ga2O3 layer is formed during the cooling process from the second temperature to the first temperature, and the Ga source of the second undoped β-Ga2O3 layer is TMGa and TEGa.

5. The β-Ga₂O₃ epitaxial structure according to any one of claims 1-4, characterized in that, The N-type doping element in the N-type doped β-Ga2O3 layer includes Si, Sn, or Ge.

6. A method for manufacturing a β-Ga2O3 epitaxial structure, characterized in that, include: Provide substrate; A β-Ga2O3 epitaxial layer is formed on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures. Each stacked structure includes stacked In-doped β-Ga2O3 layers, N-type doped β-Ga2O3 layers, and undoped β-Ga2O3 layers. The Ga source of at least one of the In-doped β-Ga2O3 layers, the N-type doped β-Ga2O3 layers, and the undoped β-Ga2O3 layers includes TMGa, and the Ga source of at least one of the layers includes TEGa.

7. The manufacturing method according to claim 6, characterized in that, The undoped β-Ga2O3 layer includes a first sub-undoped β-Ga2O3 layer and a second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top. Each stacked structure includes an In-doped β-Ga2O3 layer, an N-type doped β-Ga2O3 layer, a first sub-undoped β-Ga2O3 layer and a second sub-undoped β-Ga2O3 layer stacked sequentially from bottom to top. The In-doped β-Ga2O3 layer is formed at the first temperature, and the Ga source of the In-doped β-Ga2O3 layer is TEGa. The N-type doped β-Ga2O3 layer is formed during the heating process from the first temperature to the second temperature, and the Ga source of the N-type doped β-Ga2O3 layer is TMGa; The first undoped β-Ga2O3 layer is formed at the second temperature, and the Ga source of the first undoped β-Ga2O3 layer is TMGa. The second undoped β-Ga2O3 layer is formed during the cooling process from the second temperature to the first temperature, and the Ga source of the second undoped β-Ga2O3 layer is TMGa and TEGa.

8. The manufacturing method according to claim 7, characterized in that, The first temperature range is 700℃-830℃, and the second temperature range is 900℃-1000℃.

9. The manufacturing method according to claim 7, characterized in that, When forming the In-doped β-Ga2O3 layer, the flow rate of TEGa is 700 sccm-1000 sccm; When forming the N-type doped β-Ga2O3 layer, the flow rate of TMGa is 500 sccm-800 sccm; When forming the first undoped β-Ga2O3 layer, the flow rate of TMGa is 500 sccm-800 sccm; When forming the second undoped β-Ga2O3 layer, the flow rate of TMGa is 80 sccm-200 sccm, and the flow rate of TEGa is 400 sccm-700 sccm.

10. The manufacturing method according to claim 7, characterized in that, The In-doped β-Ga2O3 layer is formed under a first pressure and a first VI / III ratio, and the In-doped β-Ga2O3 layer has a first thickness, wherein the first pressure ranges from 15 mbar to 50 mbar, the first VI / III ratio ranges from 180 to 320, and the first thickness ranges from 10 nm to 16 nm. The N-type doped β-Ga2O3 layer is formed under a second pressure and a second VI / III ratio, and the N-type doped β-Ga2O3 layer has a second thickness, wherein the second pressure ranges from 40 mbar to 70 mbar, the second VI / III ratio ranges from 320 to 520, and the second thickness ranges from 8 nm to 12 nm. The first undoped β-Ga2O3 layer is formed under a third pressure and a third VI / III ratio, and the first undoped β-Ga2O3 layer has a third thickness, wherein the third pressure ranges from 40 mbar to 70 mbar, the third VI / III ratio ranges from 320 to 520, and the third thickness ranges from 4 nm to 8 nm. The second sub-undoped β-Ga2O3 layer is formed under a fourth pressure and a fourth VI / III ratio, and the second sub-undoped β-Ga2O3 layer has a fourth thickness, wherein the fourth pressure ranges from 20 mbar to 50 mbar, the fourth VI / III ratio ranges from 240 to 420, and the fourth thickness ranges from 1 nm to 4 nm.

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