Epitaxial layer, epitaxial layer growth method and semiconductor structure

Abstract

The invention provides an epitaxial layer growth method, an epitaxial layer and a semiconductor structure, the epitaxial layer comprises a first epitaxial layer, a second epitaxial layer and a transition layer located between the first epitaxial layer and the second epitaxial layer, the first epitaxial layer and the second epitaxial layer are different from each other, the first epitaxial layer comprises first atoms, and the second epitaxial layer comprises second atoms. The transition layer comprises the first atoms and the second atoms, in the growth process of the transition layer, the beam size of third atoms contained in the first epitaxial layer and the second epitaxial layer is kept unchanged, the temperature of the first atom source furnace is controlled to be reduced from the first starting temperature to the first ending temperature, and the temperature of the second atom source furnace is controlled to be reduced from the second starting temperature to the second ending temperature. And controlling the temperature of the second atom source furnace to rise from the second starting temperature to the second ending temperature to form a transition layer, and through the transition layer, smooth transition of energy bands can be realized, resistance caused by overlarge heterojunction interface energy level difference can be reduced, high-frequency response can be improved, transition without lattice mismatch can be realized, and crystal defects can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an epitaxial layer, an epitaxial layer growth method and a semiconductor structure. Background Art

[0002] When growing an InGaAs epitaxial layer on an InP substrate, if the lattice constant of InGaAs is greater than that of InP, compressive strain will be formed in the epitaxial layer. If the lattice constant of InGaAs is less than that of InP, tensile strain will be formed in the epitaxial layer. The composition change of InGaAs will cause its lattice constant to change. Only when the composition of InGaAs satisfies InP, the epitaxial layer will be compressed. 0.53 Ga 0.47 As can maintain lattice matching. Similar to InAlAs, when growing InAlAs epitaxial layer on InP substrate, only when the composition of InAlAs satisfies In 0.52 Al 0.48 As can be maintained in lattice matching. In addition, there are differences in the band gaps of InGaAs epitaxial layers and InAlAs epitaxial layers. Therefore, how to achieve smooth energy band transition, reduce the resistance caused by excessive energy level difference at the heterojunction interface, improve high-frequency response, achieve transition without lattice mismatch, and reduce crystal defects are urgent issues to be solved. Summary of the invention

[0003] The object of the present invention is to provide an epitaxial layer, a method for growing an epitaxial layer and a semiconductor structure to solve one or more problems in the prior art.

[0004] To solve the above technical problems, the present invention provides a method for growing an epitaxial layer, a method for growing an epitaxial layer, wherein the epitaxial layer comprises a first epitaxial layer, a second epitaxial layer, and a transition layer between the first epitaxial layer and the second epitaxial layer, the first epitaxial layer comprises a first atom, the second epitaxial layer comprises a second atom, the transition layer comprises the first atom and the second atom, and the method for growing an epitaxial layer comprises:

[0005] Growing the first epitaxial layer, and when growing the first epitaxial layer, maintaining the temperature of the first atomic source furnace at a first starting temperature;

[0006] Growing the transition layer, when growing the transition layer, keeping the beam size of the third atoms contained in both the first epitaxial layer and the second epitaxial layer the same as that when growing the first epitaxial layer, controlling the temperature of the first atomic source furnace to decrease from the first starting temperature to the first ending temperature, and controlling the temperature of the second atomic source furnace to increase from the second starting temperature to the second ending temperature;

[0007] The second epitaxial layer is grown. When the second epitaxial layer is grown, the beam size of the third atom is kept the same as that of the transition layer and the first epitaxial layer, and the temperature of the second atom source furnace is kept at the second end temperature.

[0008] Optionally, in the epitaxial layer growth method, the first starting temperature and the second ending temperature are set values, the first ending temperature is calculated based on the starting growth rate of the first epitaxial layer when growing the transition layer, the target thickness of the transition layer and the first starting temperature, and the second starting temperature is calculated based on the ending growth rate of the second epitaxial layer when growing the transition layer, the target thickness of the transition layer and the second ending temperature, wherein the starting growth rate and the target thickness are set values, and the ending growth rate is a value calculated based on the starting growth rate.

[0009] Optionally, in the epitaxial layer growth method, the first end temperature T1 is calculated according to the following first formula:

[0010]

[0011] Wherein, x is the atomic concentration of the third atom in the first epitaxial layer, 1-x is the atomic concentration of the first atom in the first epitaxial layer, A1 and B1 are constants related to the first atomic source furnace, t is the actual growth time of the transition layer, t trans is the target growth time of the transition layer, t trans It is calculated according to the target thickness and the initial growth speed V0, k1 is a proportionality coefficient, and k1 is calculated by substituting the first starting temperature into the first formula.

[0012] Optionally, in the epitaxial layer growth method, the second starting temperature T2 is calculated according to the following second formula:

[0013]

[0014] Wherein, y is the atomic concentration of the third atom in the second epitaxial layer, 1-y is the atomic concentration of the first atom in the second epitaxial layer, A2 and B2 are constants related to the second atomic source furnace, t is the actual growth time of the transition layer, t trans is the target growth time of the transition layer, t trans It is calculated according to the target thickness and the initial growth speed V0, k2 is the proportionality coefficient, and k2 is calculated by substituting the second end temperature into the second formula.

[0015] Optionally, in the epitaxial layer growth method, t transCalculated using the following formula:

[0016]

[0017] Wherein, A is the target thickness of the transition layer, x is the atomic concentration of the third atoms in the first epitaxial layer, and y is the atomic concentration of the third atoms in the second epitaxial layer.

[0018] Optionally, in the epitaxial layer growth method, one of the first epitaxial layer and the second epitaxial layer is In x Ga 1-x As layer, the other is In y Al 1-y As layer.

[0019] Optionally, in the epitaxial layer growth method, the epitaxial layer is an epitaxial layer grown on an InP substrate, and the first epitaxial layer is In 0.53 Ga 0.47 As layer, the second epitaxial layer is In 0.52 Al 0.48 As.

[0020] Optionally, in the epitaxial layer growth method, the first starting temperature is 1250K and the second ending temperature is 1430K.

[0021] The present invention also provides an epitaxial layer, wherein the epitaxial layer is grown by using the growth method as described in any of the preceding items.

[0022] The present invention also provides a semiconductor structure, comprising:

[0023] a substrate; and,

[0024] An epitaxial layer is grown on the substrate using any of the growth methods described above.

[0025] In summary, the present invention provides an epitaxial layer growth method, an epitaxial layer and a semiconductor structure, wherein the epitaxial layer includes a first epitaxial layer, a second epitaxial layer, and a transition layer located between the first epitaxial layer and the second epitaxial layer. Different from the second epitaxial layer, the first epitaxial layer contains a first atom, and different from the first epitaxial layer, the second epitaxial layer contains a second atom. The transition layer contains the first atom and the second atom. During the growth of the transition layer, the beam size of the third atom contained in both the first epitaxial layer and the second epitaxial layer is kept unchanged, the temperature of the first atomic source furnace is controlled to decrease from the first starting temperature to the first ending temperature, and the temperature of the second atomic source furnace is controlled to increase from the second starting temperature to the second ending temperature to form a transition layer. Through the transition layer, a smooth transition of energy bands can be achieved, the resistance caused by the excessive energy level difference at the heterojunction interface can be reduced, the high-frequency response can be improved, and a transition without lattice mismatch can be achieved to reduce crystal defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for growing an epitaxial layer provided in an embodiment of the present invention;

[0027] Figure 2 A flow chart of a method for growing an epitaxial layer according to an embodiment of the present invention;

[0028] Figure 3 This is a diagram showing the temperature changes of the Ga source furnace and the Al source furnace during the transition layer growth process of an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, advantages and features of the present invention clearer, the present invention is described in detail in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis required to be shown in each drawing is different, and sometimes different proportions are used. It should be recognized that relative terms such as "above", "below", "top", "bottom", "above" and "below" shown in the drawings can be used to describe the relationship between various elements. These relative terms are intended to cover different orientations of elements other than the orientations depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, for example, an element described as "above" another element will now be below the element. It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third" and the like in the specification are only used to distinguish between the various components, elements, steps, etc. in the specification, rather than to represent the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0030] An embodiment of the present invention provides a method for growing an epitaxial layer, wherein the epitaxial layer to be generated includes: a first epitaxial layer, a second epitaxial layer, and a transition layer located between the first epitaxial layer and the second epitaxial layer, wherein the first epitaxial layer is different from the second epitaxial layer and contains a first atom, and the second epitaxial layer is different from the first epitaxial layer and contains a second atom, and the transition layer contains the first atom and the second atom, and in addition, the first epitaxial layer, the second epitaxial layer, and the transition layer all contain a third atom.

[0031] like Figure 1 As shown, the epitaxial layer growth method comprises the following steps:

[0032] S1, growing the first epitaxial layer, and when growing the first epitaxial layer, maintaining the temperature of the first atomic source furnace at a first starting temperature;

[0033] S2, growing the transition layer, when growing the transition layer, keeping the beam size of the third atoms the same as that when growing the first epitaxial layer, controlling the temperature of the first atomic source furnace to decrease from the first starting temperature to the first ending temperature, and controlling the temperature of the second atomic source furnace to increase from the second starting temperature to the second ending temperature;

[0034] S3, growing the second epitaxial layer. When growing the second epitaxial layer, the beam size of the third atoms is kept the same as that of growing the transition layer and the first epitaxial layer, and the temperature of the second atomic source furnace is kept at the second end temperature.

[0035] By adopting the growth method provided in the embodiment of the present invention, a lattice-matched transition layer can be generated between the first epitaxial layer and the second epitaxial layer, and the transition layer can achieve smooth energy band transition, reduce the resistance caused by excessive energy level difference at the heterojunction interface, and improve high-frequency response.

[0036] The first starting temperature is the temperature of the first atomic source furnace when growing the first epitaxial layer, and the second ending temperature is the temperature of the second atomic source furnace when growing the second epitaxial layer. Therefore, the first starting temperature and the second ending temperature are known set values. The first ending temperature and the second starting temperature are values ​​to be determined, which are related to the target thickness value of the transition layer. Therefore, optionally, the first ending temperature and the second starting temperature can be obtained through multiple experiments while the target thickness value of the transition layer remains unchanged.

[0037] In the present embodiment, preferably, the first ending temperature is calculated based on the starting growth rate of the first epitaxial layer when growing the transition layer, the target thickness of the transition layer and the first starting temperature, and the second starting temperature is calculated based on the ending growth rate of the second epitaxial layer when growing the transition layer, the target thickness of the transition layer and the second ending temperature, wherein the starting growth rate and the target thickness are set values, and the ending growth rate is a value calculated based on the starting growth rate.

[0038] Specifically, the first end temperature T1 is calculated according to the following first formula:

[0039]

[0040] Wherein, x is the atomic concentration of the third atom in the first epitaxial layer, 1-x is the atomic concentration of the first atom in the first epitaxial layer, A1 and B1 are constants related to the first atomic source furnace, t is the actual growth time of the transition layer, t trans is the target growth time of the transition layer, t trans It is calculated according to the target thickness and the initial growth speed V0, k1 is a proportionality coefficient, and k1 is calculated by substituting the first starting temperature into the first formula.

[0041] And, the second starting temperature T2 is calculated according to the following second formula:

[0042]

[0043] Wherein, y is the atomic concentration of the third atom in the second epitaxial layer, 1-y is the atomic concentration of the first atom in the second epitaxial layer, A2 and B2 are constants related to the second atomic source furnace, t is the actual growth time of the transition layer, t trans is the target growth time of the transition layer, t trans It is calculated according to the target thickness and the initial growth speed V0, k2 is the proportionality coefficient, and k2 is calculated by substituting the second end temperature into the second formula.

[0044] The derivation process of the first formula and the second formula is as follows:

[0045] The working principle of the beam source furnace is: by precisely controlling the temperature T of the beam source furnace, the beam flux of the source furnace is controlled, thereby achieving control of the growth rate and composition. The growth rate is proportional to the beam flux. The relationship between the beam flux and the temperature T of the beam source furnace satisfies the vapor pressure equation:

[0046]

[0047] When growing the transition layer, the composition of the first atoms and the second atoms is gradually changed at the same time, and the lattice matching of the transition layer is also maintained. When changing from the first epitaxial layer to the second epitaxial layer, at t trans During the time, the relationship between the beam size of the first atom and the second atom and the growth time t should satisfy:

[0048]

[0049] Combining the above three relationship equations (1) to (3), the calculation formulas for the first end temperature T1 and the second start temperature T2 can be obtained.

[0050] In addition, when In remains unchanged, the first epitaxial layer and the second epitaxial layer should satisfy: x·V0=y·V1. According to this condition, the growth rate V1 of the second atoms in the second epitaxial layer at the end of the transition layer growth can be calculated. When the target thickness A of the transition layer is known, the growth time T of the transition layer can be further calculated. trans .

[0051] That is, in the first formula and the second formula, t trans It can be calculated using the following formula:

[0052]

[0053] The epitaxial layer growth method provided by the embodiment of the present invention is further described below with reference to specific examples.

[0054] As an example, the epitaxial layer provided in this embodiment includes: In x Ga 1-x As layer, In y Al 1-y As layer, and the In x Ga 1-x As layer and the In y Al 1-y InGaAlAs transition layer between the As layers. That is, one of the first epitaxial layer and the second epitaxial layer is In x Ga 1-x As layer, the other is In y Al 1-yDuring the growth of the InGaAlAs transition layer, the In beam size is controlled to remain unchanged, the Ga source furnace temperature is controlled to change from a first starting temperature to a first ending temperature to control the change in the Ga beam size, and the Al source furnace temperature is controlled to change from a second starting temperature to a second ending temperature to control the change in the Al beam size, thereby forming an InGaAlAs transition layer. Through the InGaAlAs transition layer, a smooth energy band transition can be achieved, the resistance caused by the excessive energy level difference at the heterojunction interface can be reduced, and the high-frequency response can be improved.

[0055] When growing the InGaAlAs transition layer, the InGaAlAs transition layer may be selected from the InGaAlAs transition layer as required. x Ga 1-x As layer changes to the In y Al 1-y As layer, also from the In y Al 1-y As layer changes to the In x Ga 1-x As layer. The growth rate is proportional to the temperature of the beam source furnace. Therefore, when the In x Ga 1-x As layer changes to the In y Al 1-y As layer, during the growth of the InGaAlAs transition layer, the Ga source furnace temperature gradually decreases, and the Al source furnace temperature gradually increases. y Al 1-y As layer changes to the In x Ga 1-x As layer, during the growth of the InGaAlAs transition layer, the temperature of the Al source furnace gradually decreases, and the temperature of the Ga source furnace gradually increases.

[0056] From the In x Ga 1-x As layer changes to the In y Al 1-y As layer as an example, Figure 2 As shown, the epitaxial layer growth method specifically includes the following steps:

[0057] S11, Growth In x Ga 1-x As layer, In x Ga 1-x When the As layer is formed, the temperature of the Ga source furnace is maintained at the first starting temperature;

[0058] S12, growing InGaAlAs transition layer. When growing InGaAlAs transition layer, keep the In beam size and the growth In x Ga1-x The same as the As layer, the Ga source furnace temperature is controlled to decrease from the first starting temperature to the first ending temperature, and the Al source furnace temperature is controlled to increase from the second starting temperature to the second ending temperature;

[0059] S13, Growth In y Al 1-y As layer, In y Al 1-y When forming the As layer, the In beam current is kept the same as in the first two steps, and the temperature of the Al source furnace is kept at the second end temperature.

[0060] It can be understood that in this example, the first epitaxial layer is In x Ga 1-x As layer, the second epitaxial layer is In y Al 1-y As layer, the first atom is Ga, the second atom is Al, the third atom is In, the first atomic source furnace is a Ga source furnace, and the second atomic source furnace is an Al source furnace.

[0061] In the above steps, x Ga 1-x The initial velocity V0 of the As layer and the target thickness of the InGaAlAs transition layer are artificially set values. The first starting temperature and the second ending temperature are respectively the values ​​of the growth rate of InGaAlAs and the target thickness of the InGaAlAs transition layer. x Ga 1-x As layer and In y Al 1-y The value of the As layer is also a known value. The first end temperature and the second start temperature are values ​​to be determined, which are related to the target thickness value of the InGaAlAs transition layer.

[0062] Taking the epitaxial layer on the InP substrate as an example, in order to ensure lattice matching with the InP substrate, the In x Ga 1-x As layer is In 0.53 Ga 0.47 As layer, the In y Al 1-y As layer is In 0.52 Al 0.48 As.

[0063] If the target thickness of the InGaAlAs transition layer is 30 nm, the In beam size remains unchanged during the growth process. 0.53 Ga 0.47 The growth rate of As is V0, which is 0.15 nm / s. When In is constant, the growth time of the transition layer can be calculated as t according to the above formula (4). trans =198s.

[0064] Combined with the actual test beam data of Ga and Al, the parameters A and B in the vapor pressure equation of Ga and Al can be calculated respectively. 0.53 Ga 0.47 As and In 0.52 Al 0.48 When the ratio of A to As is 1, the temperature of the Ga source furnace is 1250K, and the temperature of the Al source furnace is 1430K. Combining the first and second formulas above, the proportional coefficients k1 and k2 of Ga and Al can be calculated respectively. The values ​​of A, B, k1, and k2 are shown in Table 1:

[0065] Table 1

[0066]

[0067] Substituting the values ​​of A, B, k1, and k2 into the first and second formulas above, we can get Figure 3 As shown in FIG. 1 , during the growth of the InGaAlAs transition layer, the temperature of the Ga source furnace and the temperature of the Al source furnace vary with time, wherein the horizontal axis time represents the growth time of the transition layer, and the vertical axis Temperature represents the temperature of the source furnace. Substituting t=198s into the first formula, the first end temperature is calculated to be 1049.2K, and substituting t=0 into the second formula, the second start temperature is calculated to be 1167.5K, so that during the growth of the InGaAlAs transition layer, the temperature of the Ga source furnace is controlled according to Figure 3 The change curve shown is from 1250K to 1049.2K, and the temperature of the Al source furnace is controlled according to Figure 3 The curve shown is a temperature increase from 1167.5K to 1430K to obtain a crystal-matched InGaAlAs transition layer.

[0068] In 0.53 Ga 0.47 The band gap of As is 0.74 eV, and that of In 0.52 Al 0.48 The band gap of As is 1.46 eV, and the energy level gap is large. 0.53 Ga 0.47 As layer and In 0.52 Al 0.48 The InGaAlAs transition layer is formed between the As layers, which can realize the gradual change of the energy band and reduce the resistance caused by the excessive energy level difference at the heterojunction interface, thereby improving the high-frequency response.

[0069] In addition, an embodiment of the present invention further provides an epitaxial layer, which is grown by the growth method described in this embodiment. Also, a semiconductor structure is provided, which includes: a substrate; and an epitaxial layer grown on the substrate by the growth method described in this embodiment.

[0070] In summary, the epitaxial layer growth method, epitaxial layer and semiconductor structure provided in the embodiments of the present invention, the epitaxial layer includes a first epitaxial layer, a second epitaxial layer, and a transition layer located between the first epitaxial layer and the second epitaxial layer. Different from the second epitaxial layer, the first epitaxial layer contains a first atom, and different from the first epitaxial layer, the second epitaxial layer contains a second atom. The transition layer contains the first atom and the second atom. During the growth of the transition layer, the beam size of the third atom contained in both the first epitaxial layer and the second epitaxial layer is kept unchanged, the temperature of the first atomic source furnace is controlled to decrease from the first starting temperature to the first ending temperature, and the temperature of the second atomic source furnace is controlled to increase from the second starting temperature to the second ending temperature to form a transition layer. Through the transition layer, a smooth transition of the energy band can be achieved, the resistance caused by the excessive energy level difference at the heterojunction interface can be reduced, the high-frequency response can be improved, and a transition without lattice mismatch can be achieved to reduce crystal defects.

[0071] In addition, it should be recognized that although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belongs to the scope of protection of the technical solution of the present invention.

Claims

1. A method for growing an epitaxial layer, characterized in that: The epitaxial layer includes a first epitaxial layer, a second epitaxial layer, and a transition layer between the first epitaxial layer and the second epitaxial layer, which is different from the second epitaxial layer, the first epitaxial layer includes a first atom, which is different from the first epitaxial layer, the second epitaxial layer includes a second atom, the transition layer includes the first atom and the second atom, and the epitaxial layer growth method includes: Growing the first epitaxial layer, and when growing the first epitaxial layer, maintaining the temperature of the first atomic source furnace at a first starting temperature; Growing the transition layer, when growing the transition layer, keeping the beam size of the third atoms contained in both the first epitaxial layer and the second epitaxial layer the same as that when growing the first epitaxial layer, controlling the temperature of the first atomic source furnace to decrease from the first starting temperature to the first ending temperature, and controlling the temperature of the second atomic source furnace to increase from the second starting temperature to the second ending temperature; The second epitaxial layer is grown. When the second epitaxial layer is grown, the beam size of the third atom is kept the same as that of the transition layer and the first epitaxial layer, and the temperature of the second atom source furnace is kept at the second end temperature.

2. The method for growing an epitaxial layer according to claim 1, characterized in that: The first starting temperature and the second ending temperature are set values, the first ending temperature is calculated based on the starting growth rate of the first epitaxial layer when growing the transition layer, the target thickness of the transition layer and the first starting temperature, and the second starting temperature is calculated based on the ending growth rate of the second epitaxial layer when growing the transition layer, the target thickness of the transition layer and the second ending temperature, wherein the starting growth rate and the target thickness are set values, and the ending growth rate is a value calculated based on the starting growth rate.

3. The method for growing an epitaxial layer according to claim 2, characterized in that: The first end temperature T1 is calculated according to the following first formula: Wherein, x is the atomic concentration of the third atom in the first epitaxial layer, 1-x is the atomic concentration of the first atom in the first epitaxial layer, A1 and B1 are constants related to the first atomic source furnace, t is the actual growth time of the transition layer, t trans is the target growth time of the transition layer, t trans It is calculated according to the target thickness and the initial growth speed V0, k1 is a proportionality coefficient, and k1 is calculated by substituting the first starting temperature into the first formula.

4. The method for growing an epitaxial layer according to claim 2, characterized in that: The second starting temperature T2 is calculated according to the following second formula: Wherein, y is the atomic concentration of the third atom in the second epitaxial layer, 1-y is the atomic concentration of the first atom in the second epitaxial layer, A2 and B2 are constants related to the second atomic source furnace, t is the actual growth time of the transition layer, t trans is the target growth time of the transition layer, t trans It is calculated according to the target thickness and the initial growth speed V0, k2 is the proportionality coefficient, and k2 is calculated by substituting the second end temperature into the second formula.

5. The method for growing an epitaxial layer according to claim 3 or 4, characterized in that: t trans Calculated using the following formula: Wherein, A is the target thickness of the transition layer, x is the atomic concentration of the third atoms in the first epitaxial layer, and y is the atomic concentration of the third atoms in the second epitaxial layer.

6. The method for growing an epitaxial layer according to claim 1, wherein: One of the first epitaxial layer and the second epitaxial layer is In x Ga 1-x As layer, the other is In y Al 1-y As layer.

7. The method for growing an epitaxial layer according to claim 6, characterized in that: The epitaxial layer is an epitaxial layer grown on an InP substrate. 0.53 Ga 0.47 As layer, the second epitaxial layer is In 0.52 Al 0.48 As.

8. The method for growing an epitaxial layer according to claim 7, characterized in that: The first starting temperature is 1250K, and the second ending temperature is 1430K.

9. An epitaxial layer, characterized in that: The epitaxial layer is grown by using the growth method according to any one of claims 1 to 8.

10. A semiconductor structure, characterized in that: include: a substrate; and, An epitaxial layer is grown on the substrate using the growth method according to any one of claims 1 to 8.

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