Gunn diode with diamond-graphene composite heat dissipation structure and preparation method thereof

Abstract

The present invention relates to a Gunn diode with a diamond-graphene composite heat dissipation structure and a preparation method thereof, wherein the Gunn diode comprises: a substrate layer; a buffer layer, located on the upper surface of the substrate layer; a channel layer, located on the upper surface of the buffer layer; a first cap layer, located on one side of the upper surface of the channel layer; a passivation layer, located on the upper surface of the channel layer, and one side of the passivation layer is close to the first cap layer; a diamond heat dissipation layer, located on the upper surface of the passivation layer; a second cap layer, located on the side of the passivation layer away from the first cap layer; a cathode and an anode, respectively located on the upper surfaces of the first cap layer and the second cap layer; and a graphene layer covering the upper surfaces of the diamond heat dissipation layer, the anode, and the channel layer. This method can significantly reduce the heat accumulation inside the Gunn diode, significantly improve heat dissipation performance, reduce the temperature generated during operation, effectively reduce the probability of decreased work efficiency caused by thermal effects, and extend the service life of the Gunn diode.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and in particular relates to a Gunn diode with a diamond-graphene composite heat dissipation structure and a preparation method thereof. Background Art

[0002] A Gunn diode, also known as a Gunn diode or transferred electron device (TED), is a type of diode used in high-frequency electronics. Planar Gunn diodes, as terahertz signal sources, demonstrate great potential due to their compact size, low power consumption, high efficiency, and low phase noise.

[0003] However, during operation, the thermal effects of existing Gunn diodes can cause the internal temperature of the diode to rise rapidly, reducing its efficiency and potentially shortening its lifespan. Furthermore, excessively high temperatures can reduce electron mobility within the diode, increasing scattering between electrons and the crystal lattice, further degrading device performance. In short, existing Gunn diodes have extremely poor heat dissipation and are unsuitable for operating in high-temperature, high-pressure, and high-frequency oscillation environments. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a Gunn diode with a diamond-graphene composite heat dissipation structure and a method for preparing the same. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] In a first aspect, the present invention provides a Gunn diode having a diamond-graphene composite heat dissipation structure, comprising: a substrate layer; a buffer layer located on the upper surface of the substrate layer; a channel layer located on the upper surface of the buffer layer; a first cap layer located on one side of the upper surface of the channel layer; a passivation layer located on the upper surface of the channel layer, with one side of the passivation layer close to the first cap layer; a diamond heat dissipation layer located on the upper surface of the passivation layer; a second cap layer located on a side of the passivation layer away from the first cap layer; a cathode and an anode located on the upper surfaces of the first cap layer and the second cap layer, respectively; and a graphene heat dissipation layer covering the upper surfaces of the diamond heat dissipation layer, the anode, and the channel layer.

[0006] In some embodiments, the materials of the channel layer, the first cap layer and the second cap layer are all In 0.53 Ga 0.47 As.

[0007] In some embodiments, the diamond heat dissipation layer is a diamond layer or a P-type doped diamond, and the thickness of the diamond heat dissipation layer ranges from 0.2 μm to 1.0 μm.

[0008] In some embodiments, the graphene heat dissipation layer includes: a graphene layer and a graphite layer; the graphene layer covers the upper surface of the diamond heat dissipation layer and the anode, and the thickness of the graphene layer ranges from 8 nm to 12 nm.

[0009] In some embodiments, the graphene heat dissipation layer includes: a graphene layer and a graphite layer; the graphite layer covers the upper surface of the channel layer, and the thickness of the graphite layer ranges from 1.8 μm to 2.2 μm.

[0010] In some embodiments, the thickness of the first cap layer and the second cap layer are both in the range of 180 nm to 220 nm.

[0011] In some embodiments, the material of the passivation layer is Si3N 4、 SiO2 or Al2O3.

[0012] In some embodiments, the thickness of the passivation layer ranges from 45 nm to 55 nm.

[0013] In some embodiments, the material of the buffer layer is InP.

[0014] In a second aspect, the present invention provides a method for preparing a Gunn diode having a diamond-graphene composite heat dissipation structure, the preparation method being used to prepare the Gunn diode of the first aspect above; the preparation method comprising: S1, sequentially preparing a buffer layer and a channel layer on a substrate layer; S2, preparing a first cap layer on one side of the upper surface of the channel layer; S3, preparing a passivation layer on the upper surface of the channel layer and adjacent to the first cap layer; S5, preparing a second cap layer on the upper surface of the channel layer and on a side of the passivation layer away from the first cap layer; S6, etching a portion of the first cap layer and the second cap layer; On the upper surfaces of the two cap layers, a cathode region and an anode region are formed on the first cap layer and the second cap layer; S7, a cathode is formed in the cathode region, and an anode is formed in the anode region; S8, a portion of the passivation layer is etched to prepare a diamond heat dissipation layer on the upper surface of the passivation layer; S9, a graphene heat dissipation layer is prepared on the upper surfaces of the diamond heat dissipation layer, the second cap layer and the channel layer; wherein the graphene heat dissipation layer includes: a graphene layer and a graphite layer; the graphene layer covers the upper surfaces of the diamond heat dissipation layer and the anode, and the graphite layer covers the upper surface of the channel layer.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) In view of the problem that the existing Gunn diode has extremely poor heat dissipation effect and cannot be applied to the working environment of high temperature, high pressure and high frequency oscillation, the present invention provides a Gunn diode with a diamond-graphene composite heat dissipation structure. The diamond heat dissipation layer arranged on the top of the Gunn diode can dissipate heat vertically, and the graphene heat dissipation layer can enhance the lateral heat conduction and provide an additional heat dissipation path. The composite structure composed of the diamond heat dissipation layer and the graphene heat dissipation layer can greatly reduce the heat accumulation inside the Gunn diode, significantly improve the heat dissipation performance, reduce the temperature generated during operation, effectively reduce the probability of reduced work efficiency caused by thermal effects, extend the service life of the Gunn diode, and meet the working requirements in the environment of high temperature, high pressure and high frequency oscillation.

[0017] (2) When the material of the diamond heat dissipation layer is P-type doped diamond, the P-type doped diamond significantly reduces heat generation by regulating the electric field distribution and reducing the anode electric field peak, thereby improving the device's heat dissipation performance and electric field uniformity. This effectively reduces the device temperature and local overheating, thereby improving the overall electrothermal performance and reliability of the Gunn device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a schematic structural diagram of a Gunn diode having a diamond-graphene composite heat dissipation structure provided by an embodiment of the present invention;

[0019] Figure 2 1 is another structural schematic diagram of a Gunn diode having a diamond-graphene composite heat dissipation structure provided by an embodiment of the present invention;

[0020] Figure 3 This is the heat dissipation effect of the diamond layer at different thicknesses provided by the embodiment of the present invention;

[0021] Figure 4 This is an example diagram comparing the electron domain concentrations of a Gunn diode with a diamond-graphene composite heat dissipation structure provided by an embodiment of the present invention and a Gunn diode without thermal management on the top during operation;

[0022] Figure 5 1 is a schematic structural diagram of a Gunn diode including only a diamond heat dissipation layer provided by an embodiment of the present invention;

[0023] Figure 6 Schematic diagram of the structure of a Gunn diode including only a graphene heat dissipation layer provided by an embodiment of the present invention;

[0024] Figure 7 These are example diagrams of the corresponding anode currents when the top of the Gunn diode provided by the embodiment of the present invention is not thermally managed, the top is thermally managed using a diamond heat dissipation layer, the top is thermally managed using a graphene layer, and the top is thermally managed using a combination of a diamond heat dissipation layer and a graphene heat dissipation layer.

[0025] Reference numerals:

[0026] 1: substrate layer; 2: buffer layer; 3, channel layer; 4, first cap layer; 5, passivation layer; 6, diamond heat dissipation layer; 7, second cap layer; 8, cathode; 9, anode; 10, graphene heat dissipation layer; 101, graphene layer; 102, graphite layer. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

[0028] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0029] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0030] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art can understand and implement other variations of the disclosed embodiments by reviewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple situations. A single processor or other unit can implement several functions listed in the claims. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0031] To address the problem of extremely poor heat dissipation performance of existing Gunn diodes, the present invention provides a Gunn diode with a diamond-graphene composite heat dissipation structure and a preparation method thereof, which can significantly improve heat dissipation performance, reduce the temperature generated during operation, effectively reduce the probability of reduced work efficiency caused by thermal effects, and extend the service life of the Gunn diode.

[0032] The Gunn diode with a diamond-graphene composite heat dissipation structure and the preparation method thereof provided by the present invention are now described in detail with reference to the accompanying drawings.

[0033] Figure 1 FIG is a schematic diagram of the structure of a Gunn diode with a diamond-graphene composite heat dissipation structure provided by an embodiment of the present invention. Figure 1 As shown, the Gunn diode includes: a substrate layer 1; a buffer layer 2, located on the upper surface of the substrate layer 1; a channel layer 3, located on the upper surface of the buffer layer 2; a first cap layer 4, located on one side of the upper surface of the channel layer 3; a passivation layer 5, located on the upper surface of the channel layer 3, and one side of the passivation layer 5 is close to the first cap layer 4; a diamond heat dissipation layer 6, located on the upper surface of the passivation layer 5; a second cap layer 7, arranged on the side of the passivation layer 5 away from the first cap layer 4; a cathode 8 and an anode 9, respectively arranged on the upper surfaces of the first cap layer 4 and the second cap layer 7; and a graphene heat dissipation layer 10, covering the diamond heat dissipation layer 6, the anode 9 and the upper surface of the channel layer 3.

[0034] Here, the substrate layer 1 is made of diamond, SiC, Si, sapphire, etc. Diamond substrates are currently the best for heat dissipation. The width of the substrate is the width of the device. The substrate layer 1 can dissipate some heat during device operation to reduce heat accumulation at the bottom.

[0035] Here, the material of the buffer layer 2 is InP. InP, namely indium phosphide, is used to improve the growth quality of the device epitaxial layer. The thickness of the buffer layer 2 ranges from 0.15 μm to 0.25 μm, and is preferably 0.2 μm.

[0036] Here, the materials of the channel layer 3, the first cap layer 4 and the second cap layer 7 are all In 0.53 Ga 0.47 As. The first cap layer 4 and the second cap layer 7 use In 0.53 Ga 0.47 As, that is, indium gallium arsenide, helps to achieve a lower ohmic contact resistance between the device. The background doping concentration of the channel layer 3 is greater than the background doping concentration of the first cap layer 4 and the second cap layer 7. Specifically, the In 0.53 Ga 0.47 The background doping concentration of As is 8×10 16 cm -3 , the channel layer 3 maintains the n×L ac The product is greater than 10 12 cm -2 , where n is the free carrier concentration, L ac It is the distance between the anode 8 and the cathode 9. Here, the thickness of the channel layer 3 ranges from 280 nm to 320 nm, and is preferably 300 nm.

[0037] The background doping concentrations of the first cap layer 4 and the second cap layer 7 are both 2×10 18 cm -3 The thickness of the first cap layer 4 and the second cap layer 7 are both in the range of 180 nm to 220 nm, with a preferred thickness of 200 nm.

[0038] Here, the cathode 8 is located on the upper surface of the first cap layer 4, and the anode 9 is located on the upper surface of the second cap layer 7. The distance between the cathode 8 and the anode 9 is about 1.5 μm, that is, the effective width of the passivation layer 5 is about 1.5 μm. The materials of the cathode 8 and the anode 9 include one or more of Ti, Al, Ni, and Au. Here, the material of the passivation layer 5 is Si3N 4、 SiO2 or Al2O3. Moreover, the thickness of the passivation layer 5 ranges from 45nm to 55nm, preferably 50nm. A 50nm passivation layer 5 is more conducive to the nucleation and growth of the diamond heat dissipation layer 6 on the surface of the passivation layer 5, and can also avoid the diamond growth and the In 0.53 Ga 0.47 The As active area is affected by the etching in high temperature hydrogen atmosphere.

[0039] Here, the diamond heat dissipation layer 6 is a diamond layer or P-type doped diamond, and the thickness of the diamond heat dissipation layer 6 ranges from 0.2μm to 1.0μm. When the diamond heat dissipation layer 6 is a diamond layer, the high thermal conductivity of the diamond layer is much higher than that of traditional semiconductor materials, making the diamond material an ideal heat dissipation material in electronic devices operating at high power density and high frequency. In addition, when the diamond heat dissipation layer 6 is P-doped diamond, due to the depletion effect of P-doped diamond, the electric field distribution becomes more uniform after doping, reducing the electric field spike at the anode and reducing the high electric field intensity in the local area, thereby increasing the breakdown voltage of the device. This electric field redistribution can not only improve the electrical performance of the device, but also reduce heat accumulation. As the electric field distribution becomes more uniform, heat generation becomes more uniform, avoiding the occurrence of local overheating. Uniform heat distribution helps to reduce the sharp rise in local temperature, thereby improving the overall heat dissipation effect.

[0040] It should be noted that since P-doped diamond is conductive, Figure 2 FIG. 1 is another structural diagram of a Gunn diode with a diamond-graphene composite heat dissipation structure provided by an embodiment of the present invention. Figure 2 As shown in FIG, when the diamond heat dissipation layer 6 is P-doped diamond, there is a certain gap between the P-doped diamond and the first cap layer 4 and the cathode 8. It should be understood that the arrangement position and material of the other layers of the Gunn diode are different from those of the Figure 1 The position and material of the passivation layer 5 are the same, and for the sake of brevity, they are not described in detail. By covering the passivation layer 5 with P-doped diamond, the heat conduction capability in the vertical direction can be enhanced.

[0041] Here, examples of methods for growing a diamond heat dissipation layer include: using chemical vapor deposition (CVD) and metal organic chemical vapor deposition (MPCVD) to form a diamond heat dissipation layer 6 on the passivation layer 5. CVD technology utilizes a high-temperature decomposition carbon source to deposit the diamond heat dissipation layer 6 on the pre-treated passivation layer surface, while MPCVD technology uses microwave plasma to excite the carbon source, growing the diamond heat dissipation layer 6 on the passivation layer at a faster deposition rate and higher film quality.

[0042] In order to verify the heat dissipation effect of the diamond heat dissipation layer 6, simulation software is used to simulate the heat dissipation effect of the diamond heat dissipation layer with different thicknesses to determine the optimal thickness of the diamond heat dissipation layer. Figure 3 This is the heat dissipation effect of the diamond layer at different thicknesses provided by the embodiment of the present invention. The thickness is set to a range of 0.2μm to 5.0μm, such as Figure 3 As shown in the figure, when the thickness of the diamond layer 6 increases from 0.2μm to 0.8μm, the device temperature drops significantly, eventually reaching 350.8K. When the thickness of the diamond layer 6 further increases to 0.8μm and above, the rate of temperature drop slows significantly, indicating that the heat dissipation effect is saturated at this point, and increasing the thickness may introduce unnecessary mechanical stress. Therefore, a diamond layer thickness of 0.8μm is determined to be the optimal choice, ensuring effective heat dissipation without negatively impacting the device structure.

[0043] Here, the graphene heat dissipation layer 10 includes: a graphene layer (few-layer graphene, FLG) 101 and a graphite layer 102. The graphene layer 101 has an extremely high thermal conductivity of approximately 20W / cm·K; the graphite layer 102, as a heat sink material, has the characteristics of high thermal conductivity, thermal shock resistance, low reaction with other substances, high strength and flexibility, and is often used as a thermal interface material or heat diffusion plate. The graphene layer 101 covers the upper surface of the diamond heat dissipation layer 6 and the anode 9, and the thickness of the graphene layer 101 ranges from 8nm to 12nm, preferably with a thickness of 10nm; and the graphite layer 102 covers the upper surface of the channel layer 3, and the thickness of the graphite layer 102 ranges from 1.8μm to 2.2μm, preferably with a thickness of 2μm. Based on the graphene heat dissipation layer 10 provided by the present invention, it can provide additional heat dissipation paths by enhancing lateral heat conduction, improve the overall heat dissipation efficiency, and further alleviate heat accumulation within the device.

[0044] Here, an example of a method for growing a graphene heat dissipation layer may be to use CVD technology to prepare the graphene heat dissipation layer 10. Specifically, graphene is formed by decomposing a carbon source on a metal catalyst layer (such as copper or nickel), and then the catalyst is removed and the graphene is transferred to the passivation layer 5 to form the graphene heat dissipation layer 10. When preparing the graphene heat dissipation layer 10 on the diamond heat dissipation layer 6, boron is doped into the diamond surface to change the configuration of the surface carbon atoms, achieving sp2 hybridization, thereby directly growing a high-quality, defect-free graphene heat dissipation layer 10.

[0045] To address the extremely poor heat dissipation effect of existing Gunn diodes, the present invention provides a Gunn diode with a diamond-graphene composite heat dissipation structure. The diamond heat dissipation layer arranged on the top of the Gunn diode can be combined with the diamond substrate at the bottom to dissipate heat vertically. The graphene heat dissipation layer can enhance lateral heat conduction and provide an additional heat dissipation path. The composite structure composed of the diamond heat dissipation layer and the graphene heat dissipation layer can greatly reduce heat accumulation inside the Gunn diode, significantly improve heat dissipation performance, reduce the temperature generated during operation, effectively reduce the probability of reduced work efficiency due to thermal effects, extend the service life of the Gunn diode, and meet the working requirements in high-temperature, high-pressure, and high-frequency oscillation environments.

[0046] In order to verify the superiority of the Gunn diode provided by the present invention, Figure 4 This graph compares the electron domain concentration during operation of a Gunn diode with a diamond-graphene composite heat dissipation structure and a Gunn diode without thermal management on top, as provided by an embodiment of the present invention. It should be noted that electron domains are high-field regions formed by the negative differential resistance effect. These high-field regions migrate from the cathode to the anode under an applied electric field, generating stable microwave or terahertz signals. Figure 4 (a) shows the change of electron domain concentration during operation of a Gunn diode without thermal management on the top. Figure 4 (b) in the figure shows the change of electron domain concentration of the Gunn diode with diamond-graphene composite heat dissipation structure during operation. Figure 4 As shown in (a) and (b), the electron domain concentration of the Gunn diode without thermal management on the top is as high as 1.2×10 17 cm 3 The electron domain concentration of the Gunn diode provided by the present invention is as high as 1.6×10 17 cm 3 ; This shows that the electron domain concentration is higher and the working efficiency is better than that of the Gunn diode without thermal management on the top.

[0047] Figure 5 Schematic diagram of the structure of a Gunn diode including only a diamond heat dissipation layer provided by an embodiment of the present invention; Figure 6Schematic diagram of the structure of a Gunn diode including only a graphene heat dissipation layer provided by an embodiment of the present invention; Figure 7 The following are example graphs of the corresponding anode currents for the Gunn diodes provided by the embodiments of the present invention when no thermal management is performed on the top, a diamond heat dissipation layer is used for thermal management on the top, a graphene heat dissipation layer is used for thermal management on the top, and a combination of a diamond heat dissipation layer and a graphene heat dissipation layer is used for thermal management on the top. Figure 5 The structural dimensions of the Gunn diode, Figure 6 The structure and size of the Gunn diode Figure 1 The structure and size of the Gunn diode are the same, and the only difference is whether a diamond heat dissipation layer or a graphene heat dissipation layer is added.

[0048] like Figure 7 As shown in (a), compared to a Gunn diode without top thermal management, the Gunn diode with a diamond heat sink layer for top thermal management has an oscillation frequency increased to 122.4 GHz and an efficiency improvement of 1.64%. Furthermore, the anode current of the Gunn diode with a diamond heat sink layer for top thermal management is approximately 0.01 A higher than that of the Gunn diode without top thermal management.

[0049] like Figure 7 As shown in (b), compared to a Gunn diode without top thermal management, the Gunn diode with a graphene heat sink layer for top thermal management has an oscillation frequency increased to 112.4 GHz and an efficiency improvement of 1.55%. Furthermore, the anode current of the Gunn diode with a graphene heat sink layer for top thermal management is approximately 0.008 A higher than that of the Gunn diode without top thermal management.

[0050] like Figure 7 As shown in (c), compared to a Gunn diode without top thermal management, the Gunn diode with a composite diamond and graphene heat sink layer for top thermal management achieves an oscillation frequency of 115.0 GHz and an efficiency of 1.78%. Furthermore, the anode current of the Gunn diode with a composite diamond and graphene heat sink layer for top thermal management is approximately 0.012 A higher than that of the Gunn diode without top thermal management.

[0051] Visible, combined Figure 7 As can be seen from (a), (b) and (c) in the figure, the heat dissipation performance of the present invention is better than that of a Gunn diode without thermal management on the top or a Gunn diode using only a single material for heat dissipation.

[0052] Corresponding to the Gunn diode with a diamond-graphene composite heat dissipation structure proposed in the present invention, the present invention also proposes a preparation method for a Gunn diode with a diamond-graphene composite heat dissipation structure, the preparation method comprising: S1, sequentially preparing a buffer layer 2 and a channel layer 3 on a substrate layer 1; S2, preparing a first cap layer 4 on one side of the upper surface of the channel layer 3; S3, preparing a passivation layer 5 on the upper surface of the channel layer 3 and adjacent to the first cap layer 4; S5, preparing a second cap layer 7 on the upper surface of the channel layer 3 and on the side of the passivation layer 5 away from the first cap layer 4; S6, etching a portion of the first cap layer 4 and the second cap layer 7; A cathode region and an anode region are formed on the upper surface of the second cap layer 7 and located on the first cap layer 4 and the second cap layer 7; S7, a cathode 8 is formed in the cathode region, and an anode 9 is formed in the anode region; S8, a portion of the passivation layer 5 is etched to prepare a diamond heat dissipation layer 6 on the upper surface of the passivation layer 5; S9, a graphene heat dissipation layer 10 is prepared on the upper surface of the diamond heat dissipation layer 6, the second cap layer 7 and the channel layer 3; wherein, the graphene heat dissipation layer 10 includes: a graphene layer 101 and a graphite layer 102; the graphene layer 101 covers the upper surface of the diamond heat dissipation layer 6 and the anode 9, and the graphite layer 102 covers the upper surface of the channel layer 3.

[0053] It should be noted that the structure provided by the present invention, which combines a diamond-graphene layer on top of a semiconductor for composite heat dissipation, is applicable to various types of planar Gunn diodes, including bulk Gunn diodes such as indium gallium arsenide (InGaAs), GaAs, and InP; single-channel single heterojunctions such as AlGaN / GaN, InAlN / GaN, Al2O3 / Ga2O3, or AlGaN / GaN / AlGaN; and multi-channel heterojunctions such as AlGaN / GaN / AlGaN / GaN. It is also applicable to other semiconductor devices or other electronic components operating in high-temperature, high-pressure, and high-frequency oscillation conditions, not limited to Gunn diodes.

[0054] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A Gunn diode having a diamond-graphene composite heat dissipation structure, characterized in that: include: substrate layer (1); a buffer layer (2) located on the upper surface of the substrate layer (1); a channel layer (3), located on the upper surface of the buffer layer (2); A first cap layer (4) is located on one side of the upper surface of the channel layer (3); a passivation layer (5) located on the upper surface of the channel layer (3), with one side of the passivation layer (5) close to the first cap layer (4); a diamond heat dissipation layer (6), located on the upper surface of the passivation layer (5); a second cap layer (7) located on a side of the passivation layer (5) away from the first cap layer (4); A cathode (8) and an anode (9), respectively located on the upper surfaces of the first cap layer (4) and the second cap layer (7); A graphene heat dissipation layer (10) covers the upper surfaces of the diamond heat dissipation layer (6), the anode (9) and the channel layer (3).

2. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The materials of the channel layer (3), the first cap layer (4) and the second cap layer (7) are all In 0.53 Ga 0.47 As.

3. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The diamond heat dissipation layer (6) is a diamond layer or P-type doped diamond, and the thickness of the diamond heat dissipation layer (6) ranges from 0.2 μm to 1.0 μm.

4. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The graphene heat dissipation layer (10) comprises: a graphene layer (101) and a graphite layer (102); the graphene layer (101) covers the upper surface of the diamond heat dissipation layer (6) and the anode (9), and the thickness of the graphene layer (101) ranges from 8 nm to 12 nm.

5. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The graphene heat dissipation layer (10) comprises: a graphene layer (101) and a graphite layer (102); the graphite layer (102) covers the upper surface of the channel layer (3), and the thickness of the graphite layer (102) ranges from 1.8 μm to 2.2 μm.

6. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The thickness of the first cap layer (4) and the second cap layer (7) both range from 180 nm to 220 nm.

7. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The material of the passivation layer (5) is Si3N 4、 SiO2 or Al2O3.

8. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The thickness of the passivation layer (5) ranges from 45 nm to 55 nm.

9. The Gunn diode with a diamond-graphene composite heat dissipation structure according to claim 1, characterized in that: The material of the buffer layer (2) is InP.

10. A method for preparing a Gunn diode having a diamond-graphene composite heat dissipation structure, characterized in that: The preparation method is used to prepare the Gunn diode with a diamond-graphene composite heat dissipation structure according to any one of claims 1 to 9; the preparation method comprises: S1, sequentially preparing a buffer layer (2) and a channel layer (3) on a substrate layer (1); S2, preparing a first cap layer (4) on one side of the upper surface of the channel layer (3); S3, preparing a passivation layer (5) on the upper surface of the channel layer (3) and adjacent to the first cap layer (4); S5, preparing a second cap layer (7) on the upper surface of the channel layer (3) and on a side of the passivation layer (5) away from the first cap layer (4); S6, etching a portion of the upper surface of the first cap layer (4) and the second cap layer (7) to form a cathode region and an anode region located on the first cap layer (4) and the second cap layer (7); S7, forming a cathode (8) in the cathode region, and forming an anode (9) in the anode region; S8, etching a portion of the passivation layer (5) to prepare a diamond heat dissipation layer (6) on the upper surface of the passivation layer (5); S9. Preparing a graphene heat dissipation layer (10) on the upper surfaces of the diamond heat dissipation layer (6), the second cap layer (7), and the channel layer (3); wherein the graphene heat dissipation layer (10) comprises: a graphene layer (101) and a graphite layer (102); the graphene layer (101) covers the upper surfaces of the diamond heat dissipation layer (6) and the anode (9), and the graphite layer (102) covers the upper surface of the channel layer (3).

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