Terahertz device epitaxial structure and preparation method thereof, and terahertz device

Abstract

The present application relates to the field of terahertz semiconductor devices, and specifically discloses a terahertz device epitaxial structure, a preparation method thereof and a terahertz device. The terahertz device epitaxial structure comprises a substrate, a buffer layer, a lower contact layer, a first active layer and an upper contact layer which are sequentially stacked on the substrate; the first active layer is a periodic structure, each period comprising a first GaN well layer, an Al x Ga 1‑x N well layer and an Al y Ga 1‑y N barrier layer which are sequentially stacked; and x<=0.6y. The present application can improve responsivity.

Description

Technical Field

[0001] This invention relates to the field of terahertz semiconductor devices, and more particularly to an epitaxial structure of a terahertz device and its fabrication method, and a terahertz device. Background Technology

[0002] Existing terahertz devices are often based on GaAs, but GaAs has a low melting point and low thermal conductivity, limiting its use to low-temperature environments. To adapt to high-temperature applications, complex heat dissipation structures are required. GaN, with a melting point exceeding 2500℃ and high thermal conductivity, shows great promise in the fabrication of terahertz devices for high-temperature applications.

[0003] In existing GaN-based terahertz devices, GaN / AlGaN is often used as the basic unit. Due to the polarization effect, a two-dimensional electron gas is generated at the interface. When this electron gas is excited, it generates plasma waves or plasmons, which then form dipole oscillations with the metal gate and produce terahertz radiation. However, because the polarization effect in the GaN / AlGaN system is strong, it is easy to form a polarization electric field, which leads to band tilting. This increases the difficulty of energy level transitions and reduces energy conversion efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an epitaxial structure of a terahertz device and its preparation method, which has a high responsivity.

[0005] Another technical problem that this invention aims to solve is to provide a terahertz device.

[0006] To address the aforementioned technical problems, the present invention provides a terahertz device epitaxial structure, comprising a substrate and a buffer layer, a lower contact layer, a first active layer, and an upper contact layer sequentially stacked on the substrate. The first active layer has a periodic structure, and each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer and Al y Ga 1-y N layers; where x ≤ 0.6y.

[0007] As an improvement to the above technical solution, the values ​​of x and y conform to the following relationship: 0.45y ≤ x ≤ 0.55y; and / or The first GaN well layer is doped with Si at a concentration of 5 × 10⁻⁶. 18 ~5×10 19 cm -3 .

[0008] As an improvement to the above technical solution, the number of cycles in the first active layer is 5 to 20; The thickness of the first GaN well layer is 1~5nm; and / or The Al x Ga 1-x The thickness of the N-well layer is 5~15nm, and the value of x ranges from 0.02~0.1; and / or The Al y Ga 1-y The thickness of the N-barrier layer is 3~10nm, and the value of y ranges from 0.1 to 0.4.

[0009] As an improvement to the above technical solution, a second active layer is also included, which is disposed between the first active layer and the upper contact layer; The second active layer has a periodic structure, and each period includes a second GaN well layer and an In layer stacked sequentially. z Al 1-z N is a barrier layer; where z ≤ 0.5.

[0010] As an improvement to the above technical solution, the number of cycles in the second active layer is 5 to 10; The thickness of the second GaN well layer is 1~5nm; and / or The In z Al 1-z The thickness of the N-barrier layer is 1~5nm, and the value of z ranges from 0.2 to 0.4.

[0011] As an improvement to the above technical solution, the buffer layer is an intrinsic GaN layer with a thickness of 10~100nm; and / or The lower contact layer is a Si-doped GaN layer with a doping concentration of 1×10⁻⁶. 19 ~1×10 20 cm -3 Thickness of 0.5~3μm; and / or The upper contact layer is a Si-doped GaN layer with a doping concentration of 1×10⁻⁶. 19 ~1×10 20 cm -3 The thickness is 0.5~3μm.

[0012] Accordingly, the present invention also discloses a method for fabricating a terahertz device epitaxial structure, used to fabricate the above-mentioned terahertz device epitaxial structure, characterized in that it includes: Provide substrate; A buffer layer, a lower contact layer, a first active layer, and an upper contact layer are sequentially formed on the substrate. The first active layer has a periodic structure, and each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer and Al y Ga1-y N layers; where x ≤ 0.6y.

[0013] As an improvement to the above technical solution, the growth temperature of the first GaN well layer is 600~900℃, and the growth pressure is 100~600mbar; and / or The Al x Ga 1-x The growth temperature of the N-well layer is 800~1000℃, and the growth pressure is 100~600 mbar; and / or The Al y Ga 1-y The growth temperature of the N-barrier layer is 800~900℃, and the growth pressure is 100~600mbar.

[0014] As an improvement to the above technical solution, the epitaxial structure of the terahertz device further includes a second active layer, which is disposed between the first active layer and the upper contact layer; the second active layer has a periodic structure, and each period includes a second GaN well layer and an In layer stacked sequentially. z Al 1-z N barrier layers; where z ≤ 0.5; The growth temperature of the second GaN well layer is 600~900℃, and the growth pressure is 100~600mbar; and / or The In z Al 1-z The growth temperature of the N barrier layer is 700~1000℃, and the growth pressure is 100~600mbar.

[0015] Accordingly, the present invention also discloses a terahertz device, which includes the above-described terahertz device epitaxial structure.

[0016] Implementing this invention has the following beneficial effects: The epitaxial structure of the terahertz device in one embodiment of the present invention includes a first active layer, which is a periodic structure, and each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer and Al y Ga 1-y N-layer barrier; where x ≤ 0.6y. The first active layer in this invention introduces Al with a low Al content. x Ga 1-x The N-well layer can significantly weaken the polarization electric field, thereby obtaining an almost flat quantum well region. This greatly reduces the transition energy of the quantum well sublevels, effectively improving the energy conversion efficiency. It also reduces the recombination luminescence of other energy levels, making the terahertz band more stable, improving the responsivity, and reducing the noise equivalent power (NEP). Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the epitaxial structure of a terahertz device in one embodiment of the present invention; Figure 2 This is a schematic diagram of the epitaxial structure of a terahertz device in another embodiment of the present invention; Figure 3 This is a flowchart of a method for preparing a terahertz epitaxial structure according to an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0021] Please see Figure 1 This invention discloses an epitaxial structure for a terahertz device, comprising a substrate 100 and a buffer layer 200, a lower contact layer 300, a first active layer 400, and an upper contact layer 500 sequentially stacked on the substrate 100; wherein the first active layer 400 has a periodic structure, and each period includes a first GaN well layer 410 and an Al layer sequentially stacked on the substrate 100. x Ga 1-x N-well layer 420 and Aly Ga 1-y N-layer 430; wherein, x ≤ 0.6y. The first active layer 400 of the present invention introduces Al with a low Al component content. x Ga 1-x The N-well layer 420 can significantly weaken the polarization electric field, thereby obtaining an almost flat quantum well region. This greatly reduces the transition energy of the quantum well sublevels, effectively improving the energy conversion efficiency. It also reduces the recombination luminescence of other energy levels, making the terahertz band more stable, improving the responsivity, and reducing the noise equivalent power (NEP).

[0022] The substrate 100 can be a silicon substrate, a sapphire substrate, a silicon carbide substrate, or a gallium nitride substrate, but is not limited to these. Preferably, it is a gallium nitride substrate. Gallium nitride substrates not only have high lattice matching and excellent thermal conductivity, but can also significantly reduce epitaxial layer stress and dislocation density, providing a foundation for the high-quality growth of subsequent multilayer heterostructures.

[0023] The buffer layer 200 is an intrinsic GaN layer, but is not limited thereto. The thickness of the buffer layer 200 is 10~100nm, exemplarily 15nm, 30nm, 45nm, 60nm, 75nm or 90nm, but is not limited thereto.

[0024] The lower contact layer 300 is a Si-doped GaN layer with a doping concentration of 1×10⁻⁶. 19 cm -3 ~1×10 20 cm -3 For example, 2.5 × 10 19 cm -3 4.5×10 19 cm -3 6.5×10 19 cm -3 8.5×10 19 cm -3 Or 9.5×10 19 cm -3 However, it is not limited to this.

[0025] Specifically, the thickness of the lower contact layer 300 is 0.5~3μm, exemplarily 0.8μm, 1.2μm, 1.6μm, 2.0μm, 2.4μm or 2.8μm, but not limited thereto. Preferably, it is 1μm~2μm.

[0026] The number of cycles in the first active layer 400 is 5 to 20, exemplarily 8, 10, 12, 14, 16 or 19, but not limited thereto. Preferably it is 5 to 12.

[0027] The thickness of the first GaN well layer 410 is 1-5 nm. If the thickness is too thin, the carrier localization effect is weakened, leading to a decrease in radiative recombination efficiency; if the thickness is too thick, strain relaxation and defect proliferation are easily induced, which degrades the terahertz response performance. For example, the thickness of the first GaN well layer 410 is 1.5 nm, 2.0 nm, 2.5 nm, 3.0 nm, 3.5 nm, or 4.5 nm, but is not limited to these.

[0028] Among them, Al x Ga 1-x The thickness of the N-well layer 420 is 5~15nm. If it is too thin, polarization control will be insufficient; if it is too thick, lattice mismatch and increased interface roughness will occur. For example, Al x Ga 1-x The thickness of the N-well layer 420 is 6 nm, 8 nm, 10 nm, 12 nm or 14 nm, but is not limited to these. Preferably it is 5 to 10 nm.

[0029] Specifically, Al x Ga 1-x The proportion of Al component in the N-well layer 420 (i.e., x) is 0.02~0.15. If the proportion of Al component is too high, the interfacial polarization electric field will be too strong, which will easily cause carrier tunneling leakage and reduce the terahertz response performance. If the proportion of Al component is too low, the polarization control capability will be insufficient. For example, the value of x is 0.03, 0.05, 0.07, 0.09, 0.11 or 0.13, preferably 0.02~0.10.

[0030] Among them, Al y Ga 1-y The thickness of the N-barrier layer 430 is 3-10 nm. If its thickness is too thin, the barrier height is insufficient, and the two-dimensional electron gas concentration is low. If its thickness is too thick, it easily leads to increased carrier transport resistance, enhanced interface scattering, and significantly weakened terahertz radiation efficiency. For example, Al y Ga 1-y The thickness of the N-barrier layer 430 is 4 nm, 5.5 nm, 6.5 nm, 7.5 nm, or 9 nm, but is not limited to these. Preferably, it is 5 to 10 nm.

[0031] Specifically, Al y Ga 1-y The proportion of Al component in the N-barrier layer 430 (i.e., y is 0.1~0.4). If the proportion of Al component is too high, the barrier will be too high, hindering carrier injection; if it is too low, the barrier will be insufficient, making it difficult to effectively confine the two-dimensional electron gas. For example, the value of y can be 0.15, 0.20, 0.25, 0.30 or 0.35, but is not limited to these. Preferably, it is 0.2~0.4.

[0032] The upper contact layer 500 is a Si-doped GaN layer with a doping concentration of 1×10⁻⁶. 19 cm -3 ~1×10 20 cm -3 For example, 2.5 × 10 19 cm -3 4.5×10 19 cm -3 6.5×10 19 cm -3 8.5×10 19 cm -3 Or 9.5×10 19 cm -3 However, it is not limited to this.

[0033] Specifically, the thickness of the upper contact layer 500 is 0.5~3μm, exemplarily 0.8μm, 1.2μm, 1.6μm, 2.0μm, 2.4μm or 2.8μm, but not limited thereto. Preferably, it is 1μm~2μm.

[0034] Preferably, in some implementations, the values ​​of x and y conform to the following relationship: 0.45y≤x≤0.55y. This constraint can effectively balance the polarization matching degree and band offset between the well / barrier layers, suppress the accumulation of interface charge and energy level misalignment, thereby improving carrier locality and terahertz radiation quantum efficiency.

[0035] Preferably, in some embodiments, the first GaN well layer 410 is doped with Si at a doping concentration of 5 × 10⁻⁶. 18 ~5×10 19 cm -3 By doping Si into the first GaN well layer 410, the density and mobility of the two-dimensional electron gas can be optimized, further improving the terahertz response performance.

[0036] Preferably, please refer to Figure 2 In some implementations, the epitaxial structure of the terahertz device further includes a second active layer 600, which is disposed between the first active layer 400 and the upper contact layer 500. The second active layer 600 has a periodic structure, and each period includes a second GaN well layer 610 and an In layer stacked sequentially. z Al 1-z The N-barrier layer is 620, where z ≤ 0.5. By introducing a second active layer 600, the photon energy tuning range can be extended, the quantum cascade transition efficiency in the terahertz band can be enhanced, and the responsivity can be further improved.

[0037] Specifically, the number of cycles in the second active layer 600 is 5 to 15, exemplarily 7, 9, 11 or 13, but not limited thereto. Preferably, the number of cycles in the second active layer 600 is 5 to 10.

[0038] The thickness of the second GaN well layer 610 is 1~5nm, exemplarily 1.5nm, 2.5nm, 3.5nm or 4.5nm, but not limited thereto. Preferably it is 2~4nm.

[0039] Among them, In z Al 1-z The thickness of the N-barrier layer 620 is 1~5nm, exemplarily 1.5nm, 2.5nm, 3.5nm or 4.5nm, but not limited thereto. Preferably it is 2~4nm.

[0040] Specifically, in z Al 1-z The proportion of In component in the N-barrier layer 620 (i.e., z) is ≤0.5. If z>0.5, the lattice mismatch with the second GaN well layer 610 is too high, resulting in a shortened carrier lifetime. Preferably, in some embodiments, the value of z ranges from 0.2 to 0.4, such as 0.22, 0.25, 0.28, 0.31, 0.34, 0.37, or 0.39, but is not limited thereto.

[0041] Accordingly, please see Figure 3 In one embodiment of the present invention, a method for fabricating a terahertz device epitaxial structure is also disclosed, which is used to fabricate the above-mentioned terahertz device epitaxial structure, comprising: S1: Provides a substrate; S2: A buffer layer, a lower contact layer, a first active layer, and an upper contact layer are sequentially formed on the substrate.

[0042] The first active layer has a periodic structure, and each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer and Al y Ga 1-y N-layer barrier; where x ≤ 0.6y. The first active layer in this invention incorporates Al with a low Al content. x Ga 1-x The N-well layer can significantly weaken the polarization electric field, thereby obtaining an almost flat quantum well region. This greatly reduces the transition energy of the quantum well sublevels, effectively improving the energy conversion efficiency. It also reduces the recombination luminescence of other energy levels, making the terahertz band more stable, improving the responsivity, and reducing the noise equivalent power (NEP).

[0043] Preferably, in some embodiments, step S2 includes: S21: A buffer layer is formed on the substrate; In some implementations, an intrinsic GaN layer is grown by MOCVD as a buffer layer. The growth temperature of the buffer layer is 800~1050℃, and the growth pressure is 50~200mbar.

[0044] S22: Form a lower contact layer on the buffer layer; In some implementations, a Si-doped GaN layer is grown by MOCVD as the lower contact layer. The growth temperature of the lower contact layer is 800~1200℃, and the growth pressure is 30~150mbar.

[0045] S23: Grow the first active layer on the lower contact layer; In some implementations, a first GaN well layer and an Al layer are periodically grown using MOCVD. x Ga 1-x N-well layer and Al y Ga 1-y The process continues until the first active layer is obtained, using N barrier layers.

[0046] The growth temperature of the first GaN well layer is 600~900℃, and the growth pressure is 100~600mbar; Al x Ga 1-x The growth temperature of the N-well layer is 800~1000℃, and the growth pressure is 100~600mbar; Al y Ga 1-y The growth temperature of the N-barrier layer is 800~900℃, and the growth pressure is 100~600mbar.

[0047] S24: Grow a second active layer on the first active layer; In some implementations, a second GaN well layer and In are periodically grown using MOCVD. z Al 1-z The N-barrier layer is used until the second active layer is obtained.

[0048] Specifically, the growth temperature of the second GaN well layer is 600~900℃, and the growth pressure is 100~600mbar; In z Al 1- z The growth temperature of the N barrier layer is 700~1000℃, and the growth pressure is 100~600mbar.

[0049] S25: Grow an upper contact layer on the second active layer; In some implementations, a Si-doped GaN layer is grown by MOCVD as the upper contact layer. The growth temperature of the upper contact layer is 800~1200℃, and the growth pressure is 30~150mbar.

[0050] Accordingly, the present invention also discloses a terahertz device, which includes the above-described terahertz device epitaxial structure.

[0051] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides a terahertz device epitaxial structure, which includes a substrate (GaN), a buffer layer, a lower contact layer, a first active layer and an upper contact layer sequentially stacked on the substrate.

[0052] The buffer layer is an intrinsic GaN layer with a thickness of 25 nm. The lower contact layer is a Si-doped GaN layer with a thickness of 1.5 μm and a doping concentration of 5.5 × 10⁻⁶. 19 cm -3 The upper contact layer is a Si-doped GaN layer with a thickness of 1.2 μm and a doping concentration of 6 × 10⁻⁶. 19 cm -3 .

[0053] The first active layer has a periodic structure with 15 periods. Each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer (x=0.09) and Al y Ga 1-y N-barrier layer (y=0.15); wherein, the thickness of the first GaN well layer is 3nm, Al x Ga 1-x The thickness of the N-well layer is 8.5 nm, and the Al... y Ga 1-y The thickness of the N-barrier layer is 8 nm.

[0054] Example 2 This embodiment provides a terahertz device epitaxial structure, which includes a substrate (GaN), a buffer layer, a lower contact layer, a first active layer and an upper contact layer sequentially stacked on the substrate.

[0055] The buffer layer is an intrinsic GaN layer with a thickness of 25 nm. The lower contact layer is a Si-doped GaN layer with a thickness of 1.5 μm and a doping concentration of 5.5 × 10⁻⁶. 19 cm -3 The upper contact layer is a Si-doped GaN layer with a thickness of 1.2 μm and a doping concentration of 6 × 10⁻⁶. 19 cm -3 .

[0056] The first active layer has a periodic structure with 15 periods. Each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer (x=0.08) and Aly Ga 1-y N-barrier layer (y=0.15); wherein, the thickness of the first GaN well layer is 3nm, Al x Ga 1-x The thickness of the N-well layer is 8.5 nm, and the Al... y Ga 1-y The thickness of the N-barrier layer is 8 nm.

[0057] Example 3 This embodiment provides a terahertz device epitaxial structure, which includes a substrate (GaN), a buffer layer, a lower contact layer, a first active layer and an upper contact layer sequentially stacked on the substrate.

[0058] The buffer layer is an intrinsic GaN layer with a thickness of 25 nm. The lower contact layer is a Si-doped GaN layer with a thickness of 1.5 μm and a doping concentration of 5.5 × 10⁻⁶. 19 cm -3 The upper contact layer is a Si-doped GaN layer with a thickness of 1.2 μm and a doping concentration of 6 × 10⁻⁶. 19 cm -3 .

[0059] The first active layer has a periodic structure with 15 periods. Each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer (x=0.08) and Al y Ga 1-y An N-barrier layer (y=0.15); wherein, the first GaN well layer is doped with Si element, and the doping concentration is 8.5×10⁻⁶. 18 cm -3 Its thickness is 3 nm. Al x Ga 1-x The thickness of the N-well layer is 8.5 nm, and the Al... y Ga 1-y The thickness of the N-barrier layer is 8 nm.

[0060] Example 4 This embodiment provides a terahertz device epitaxial structure, which includes a substrate (GaN), a buffer layer, a lower contact layer, a first active layer, a second active layer and an upper contact layer sequentially stacked on the substrate.

[0061] The buffer layer is an intrinsic GaN layer with a thickness of 25 nm. The lower contact layer is a Si-doped GaN layer with a thickness of 1.5 μm and a doping concentration of 5.5 × 10⁻⁶. 19 cm -3 The upper contact layer is a Si-doped GaN layer with a thickness of 1.2 μm and a doping concentration of 6 × 10⁻⁶. 19 cm -3 .

[0062] The first active layer has a periodic structure with 15 periods. Each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer (x=0.08) and Al y Ga 1-y An N-barrier layer (y=0.15); wherein, the first GaN well layer is doped with Si element, and the doping concentration is 8.5×10⁻⁶. 18 cm -3 Its thickness is 3 nm. Al x Ga 1-x The thickness of the N-well layer is 8.5 nm, and the Al... y Ga 1-y The thickness of the N-barrier layer is 8 nm.

[0063] The second active layer has a periodic structure with 8 periods, each period consisting of a second GaN well layer and an In layer stacked sequentially. z Al 1-z The N-type barrier layer (z=0.35) has a second GaN well layer with a thickness of 2 nm. z Al 1-z The thickness of the N-barrier layer is 3 nm.

[0064] Comparative Example 1 This comparative example provides a terahertz device epitaxial structure, which differs from Example 1 in that: Excluding Al x Ga 1-x The N-well layer is the same as in Example 1.

[0065] The epitaxial structures of terahertz devices obtained in Examples 1-4 and Comparative Example 1 were fabricated into devices and their photoelectric response characteristics were tested. The specific test results are shown in the table below:

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A terahertz device epitaxial structure, characterized in that, It includes a substrate and a buffer layer, a lower contact layer, a first active layer and an upper contact layer sequentially stacked on the substrate; The first active layer has a periodic structure, and each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer and Al y Ga 1-y N layers; where x ≤ 0.6y.

2. The terahertz device epitaxial structure as described in claim 1, characterized in that, The values ​​of x and y conform to the following relationship: 0.45y ≤ x ≤ 0.55y; and / or The first GaN well layer is doped with Si at a concentration of 5 × 10⁻⁶. 18 ~5×10 19 cm -3 .

3. The terahertz device epitaxial structure as described in claim 1, characterized in that, The number of cycles in the first active layer is 5 to 20; The thickness of the first GaN well layer is 1~5nm; and / or The Al x Ga 1-x The thickness of the N-well layer is 5~15nm, and the value of x ranges from 0.02~0.1; and / or The Al y Ga 1-y The thickness of the N-barrier layer is 3~10nm, and the value of y ranges from 0.1 to 0.

4.

4. The terahertz device epitaxial structure as described in any one of claims 1 to 3, characterized in that, It also includes a second active layer, which is disposed between the first active layer and the upper contact layer; The second active layer has a periodic structure, and each period includes a second GaN well layer and an In layer stacked sequentially. z Al 1-z N is a barrier layer; where z ≤ 0.

5.

5. The terahertz device epitaxial structure as described in claim 4, characterized in that, The number of periods in the second active layer is 5 to 10; The thickness of the second GaN well layer is 1~5nm; and / or The In z Al 1-z The thickness of the N-barrier layer is 1~5nm, and the value of z ranges from 0.2 to 0.

4.

6. The terahertz device epitaxial structure as described in claim 1, characterized in that, The buffer layer is an intrinsic GaN layer with a thickness of 10~100 nm; and / or The lower contact layer is a Si-doped GaN layer with a doping concentration of 1×10⁻⁶. 19 ~1×10 20 cm -3 Thickness of 0.5~3μm; and / or The upper contact layer is a Si-doped GaN layer with a doping concentration of 1×10⁻⁶. 19 ~1×10 20 cm -3 The thickness is 0.5~3μm.

7. A method for fabricating a terahertz device epitaxial structure, used to fabricate the terahertz device epitaxial structure as described in any one of claims 1 to 6, characterized in that, include: Provide substrate; A buffer layer, a lower contact layer, a first active layer, and an upper contact layer are sequentially formed on the substrate. The first active layer has a periodic structure, and each period includes a first GaN well layer and an Al layer stacked sequentially. x Ga 1-x N-well layer and Al y Ga 1-y N layers; where x ≤ 0.6y.

8. The method for fabricating the epitaxial structure of a terahertz device as described in claim 7, characterized in that, The growth temperature of the first GaN well layer is 600~900℃, and the growth pressure is 100~600mbar; and / or The Al x Ga 1-x The N-well layer is grown at a temperature of 800–1000 °C and a growth pressure of 100–600 mbar; and / or The Al y Ga 1-y The growth temperature of the N-barrier layer is 800~900℃, and the growth pressure is 100~600mbar.

9. The method for fabricating the epitaxial structure of a terahertz device as described in claim 7, characterized in that, The epitaxial structure of the terahertz device further includes a second active layer disposed between the first active layer and the upper contact layer; the second active layer has a periodic structure, and each period includes a second GaN well layer and an In layer stacked sequentially. z Al 1-z N-level barrier layer; where z ≤ 0.5; The growth temperature of the second GaN well layer is 600~900℃, and the growth pressure is 100~600mbar; and / or The In z Al 1-z The growth temperature of the N barrier layer is 700~1000℃, and the growth pressure is 100~600mbar.

10. A terahertz device, characterized in that, Including the terahertz device epitaxial structure as described in any one of claims 1 to 6.

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