Homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode and preparation method thereof

Abstract

The present invention discloses a homomorphic silicon carbide gallium oxide heterojunction ultraviolet photodiode and a preparation method thereof. The ultraviolet photodiode comprises a substrate, an epitaxial layer superimposed on the substrate, a moth-eye array passivation layer superimposed on the epitaxial layer, a Schottky contact layer superimposed on the upper surface of the epitaxial layer except for the sub-passivation layer, an anode superimposed on the Schottky contact layer, a passivation protection layer superimposed on the moth-eye array passivation layer and the anode, an ohmic contact layer superimposed on the substrate, and a cathode superimposed on the ohmic contact layer. The moth-eye array passivation layer comprises a plurality of spaced-apart moth-eye-shaped sub-passivation layers, and the sub-passivation layers are made of alkaline-earth-doped silicon oxide. The homomorphic silicon carbide gallium oxide heterojunction ultraviolet photodiode provided by the present invention can effectively reduce light reflection and improve light utilization, and the preparation process is simple and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a homotype silicon carbide gallium oxide heterojunction ultraviolet photodiode and a preparation method thereof. Background Art

[0002] Silicon carbide gallium oxide heterojunction UV detectors combine the high thermal conductivity and chemical stability of SiC (silicon carbide) with the ultra-wide bandgap and high UV sensitivity of Ga2O3 (gallium oxide), enabling efficient and stable UV detection. Their excellent material properties hold significant potential for applications in high-temperature, high-power UV imaging, environmental monitoring, and UV communications.

[0003] The anti-reflection structure in the existing silicon carbide gallium oxide heterojunction ultraviolet photodiode requires additional process steps during preparation and cannot be prepared using standard equipment. Therefore, it is not conducive to industrial promotion and the preparation process is complicated. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode and a preparation method thereof.

[0005] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode, the homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode comprising:

[0007] substrate;

[0008] an epitaxial layer superimposed on the substrate;

[0009] a moth-eye array passivation layer superimposed on the epitaxial layer; the moth-eye array passivation layer comprises a plurality of moth-eye-shaped sub-passivation layers arranged at intervals; the material of the sub-passivation layers is alkaline earth-doped silicon oxide;

[0010] a Schottky contact layer superimposed on the upper surface of the epitaxial layer except the sub-passivation layer;

[0011] an anode stacked on the Schottky contact layer;

[0012] a passivation protection layer superimposed on the moth-eye array passivation layer and the anode;

[0013] an ohmic contact layer superimposed below the substrate;

[0014] A cathode is stacked below the ohmic contact layer.

[0015] Optionally, the epitaxial layer includes a first epitaxial layer and a second epitaxial layer stacked on the first epitaxial layer.

[0016] Optionally, the material of the first epitaxial layer is SiC; the material of the second epitaxial layer is Ga2O3; the thickness of the first epitaxial layer ranges from 1.5 μm to 2 μm; the thickness of the second epitaxial layer ranges from 0.2 μm to 0.5 μm.

[0017] Optionally, the thickness of the moth-eye array passivation layer ranges from 500 nm to 1000 nm.

[0018] Optionally, the material of the ohmic contact layer is Ni; the thickness of the ohmic contact layer ranges from 60 nm to 70 nm.

[0019] Optionally, the material of the Schottky contact layer is Pt; the thickness of the Schottky contact layer ranges from 60 nm to 70 nm.

[0020] Optionally, the material of the anode is Al; the thickness of the anode ranges from 500 nm to 1000 nm.

[0021] Optionally, the cathode is formed by stacking Ti, Ni and Ag in sequence from bottom to top.

[0022] In a second aspect, the present invention provides a method for preparing a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode, the preparation method comprising:

[0023] Select a substrate;

[0024] growing an epitaxial layer on the substrate;

[0025] Depositing alkaline earth-doped silicon oxide on the entire surface of the epitaxial layer, and etching the entire surface of the alkaline earth-doped silicon oxide through an etching process to form an initial passivation layer array; the initial passivation layer array includes a plurality of alkaline earth-doped silicon oxide blocks arranged at intervals;

[0026] Depositing a Schottky contact layer on the upper surface of the epitaxial layer except for the alkaline earth doped silicon oxide block, and depositing an ohmic contact layer on the lower surface of the substrate;

[0027] Annealing the Schottky contact layer and the ohmic contact layer using a thermal annealing process, and simultaneously reflowing the alkaline earth-doped silicon oxide blocks treated by the thermal annealing process to form moth-eye-shaped sub-passivation layers, wherein a plurality of the sub-passivation layers form a moth-eye array passivation layer;

[0028] Depositing metal on the upper surface of the Schottky contact layer to form an anode;

[0029] forming a passivation protection layer on the moth-eye array passivation layer and the upper surface of the anode;

[0030] A cathode is deposited on the lower surface of the ohmic contact layer.

[0031] Optionally, before metal deposition is performed on the upper surface of the Schottky contact layer to form an anode, the preparation method further comprises:

[0032] The ohmic contact layer is transparentized using a liquid chemical, and the metal residue on the upper surface of the moth-eye array passivation layer is removed. The volume ratio of nitric acid, BOE and deionized water in the liquid chemical is 1:1:5.

[0033] The present invention provides a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode. The moth-eye array passivation layer comprises a plurality of spaced-apart moth-eye-shaped sub-passivation layers, forming numerous depressions and protrusions that effectively reduce light reflection. Furthermore, the sub-passivation layers are made of alkaline-earth-doped silicon oxide. By combining the alkaline-earth-doped silicon oxide with the microstructure of the moth-eye array passivation layer, light reflection can be further reduced, thereby improving light utilization. Furthermore, based on the properties of alkaline-earth-doped silicon oxide, the moth-eye-shaped sub-passivation layers in the moth-eye array passivation layer can be formed by reflow during the preparation of the Schottky contact layer and the ohmic contact layer, making the preparation of the moth-eye array passivation layer simpler, more efficient, and less costly.

[0034] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a cross-sectional view of a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode provided in an embodiment of the present invention;

[0036] Figure 2 This is a schematic flow chart of a method for preparing a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode provided by an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the preparation process of a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode provided in an embodiment of the present invention.

[0038] Figure numerals: 1, substrate; 2, first epitaxial layer; 3, second epitaxial layer; 4, moth-eye array passivation layer; 5, Schottky contact layer; 6, ohmic contact layer; 7, anode; 8, passivation protection layer; 9, cathode. DETAILED DESCRIPTION

[0039] 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.

[0040] In order to solve the problem that the existing anti-reflection structure is difficult to realize and the preparation process is complicated, the embodiment of the present invention provides a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode, see Figure 1 , Figure 1 This is a cross-sectional view of a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode provided in an embodiment of the present invention. The homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode includes a substrate 1, an epitaxial layer, a moth-eye array passivation layer 4, a Schottky contact layer 5, an anode 7, an ohmic contact layer 6, a cathode 9 and a passivation protection layer 8.

[0041] The substrate 1 refers to the basic material for growing semiconductor crystals and is an important foundation for manufacturing semiconductor devices such as transistors and integrated circuits.

[0042] In the embodiment of the present invention, the material of the substrate 1 can be SiC. SiC has the characteristics of high thermal conductivity and strong chemical stability. The thickness of the substrate 1 can be 350 μm, and the concentration can be 5×10 18 cm -3 .

[0043] Specifically, the substrate 1 may be an n+ type SiC substrate.

[0044] In the embodiment of the present invention, the epitaxial layer is stacked on the substrate 1. The epitaxial layer stacked on the substrate 1 can be used to achieve matching between semiconductor materials with different lattice constants, thereby realizing the preparation of a heterostructure.

[0045] In the embodiment of the present invention, the epitaxial layer includes a first epitaxial layer 2 and a second epitaxial layer 3 stacked on the first epitaxial layer 2 .

[0046] The material of the first epitaxial layer 2 is SiC, which is the same as the material of the substrate 1, so the first epitaxial layer 2 is homoepitaxial. The material of the second epitaxial layer 3 is Ga2O3, which has the characteristics of ultra-wide band gap and high ultraviolet light sensitivity. It is different from the material of the substrate 1, so the second epitaxial layer 3 is heteroepitaxial.

[0047] In the embodiment of the present invention, the thickness of the first epitaxial layer 2 is in the range of 1.5 μm to 2 μm, and the thickness of the second epitaxial layer 3 is in the range of 0.2 μm to 0.5 μm.

[0048] In the embodiment of the present invention, the moth-eye array passivation layer 4 is stacked on the epitaxial layer.

[0049] In an embodiment of the present invention, the moth-eye array passivation layer 4 includes a plurality of spaced-apart moth-eye-shaped sub-passivation layers. The numerous depressions and protrusions formed by the plurality of spaced-apart moth-eye-shaped sub-passivation layers can effectively reduce light reflection and increase light absorption, thereby improving the performance of the ultraviolet photodiode.

[0050] In the embodiment of the present invention, the thickness of the moth-eye array passivation layer 4 is in the range of 500 nm to 1000 nm, the interval between each two sub-passivation layers is in the range of 500 nm to 800 nm, and the width of the sub-passivation layer is in the range of 500 nm to 800 nm.

[0051] In an embodiment of the present invention, the sub-passivation layer is made of alkaline-earth-doped silicon oxide. The doping element in the alkaline-earth-doped silicon oxide may be an alkaline-earth metal such as calcium (Ca), magnesium (Mg), and strontium (Sr). By doping the alkaline-earth metal into the silicon oxide, the electronic and optical properties of the oxide can be improved.

[0052] Integrating alkaline-earth-doped silicon oxide with the moth-eye array's microstructure in the moth-eye array passivation layer 4 further reduces reflection and improves light incidence and absorption efficiency. Furthermore, by using alkaline-earth-doped silicon oxide as the sub-passivation layer material, during the device fabrication process, when the Schottky contact layer 5 and the ohmic contact layer 6 are thermally annealed, the alkaline-earth-doped silicon oxide is simultaneously affected by the annealing process and reflowed to form the moth-eye array passivation layer 4, making the fabrication of the moth-eye array simpler, more efficient, and less costly.

[0053] In the embodiment of the present invention, each sub-passivation layer in the moth-eye array passivation layer 4 is hemispherical, and its bottom surface can be circular or hexagonal, etc., which is not limited here.

[0054] In this embodiment of the present invention, a Schottky contact layer 5 is superimposed on the upper surface of the epitaxial layer, excluding the sub-passivation layer. The Schottky contact layer 5 is the layer formed by the contact between the metal and the semiconductor. In the Schottky contact layer 5, a potential barrier is formed between the metal and the semiconductor, which controls the flow of electrons and has a rectifying effect.

[0055] In the embodiment of the present invention, the material of the Schottky contact layer 5 is Pt (platinum); the thickness of the Schottky contact layer 5 is in the range of 60 nm to 70 nm.

[0056] In the embodiment of the present invention, the anode 7 is superimposed on the Schottky contact layer 5. The material of the anode 7 is Al (aluminum). Anodes 7 made of Al have excellent conductivity and adhesion, and are low in cost. The thickness of the anode 7 can range from 500 nm to 1000 nm.

[0057] In the embodiment of the present invention, the passivation protection layer 8 is superimposed on the moth-eye array passivation layer 4 and the anode 7 .

[0058] In the embodiment of the present invention, the passivation protective layer 8 located above the moth-eye array passivation layer 4 can further reduce surface light reflection. Furthermore, the passivation protective layer 8 can serve as a barrier between the moth-eye array passivation layer 4 and the anode 7, preventing the layers below the passivation protective layer 8 from being contaminated, oxidized, or corroded, thereby maintaining the stability of the UV photodiode and extending the device's service life. The passivation protective layer 8 can also provide a certain degree of thermal isolation.

[0059] In the embodiment of the present invention, the material of the passivation protection layer 8 can be Si y N x (silicon nitride), the thickness of which can range from 500nm to 600nm.

[0060] In the embodiment of the present invention, the ohmic contact layer 6 is superimposed on the substrate 1 , and the cathode 9 is superimposed on the ohmic contact layer 6 .

[0061] The ohmic contact layer 6 located between the substrate 1 and the cathode 9 can provide a low-resistance connection between the substrate 1 and the cathode 9 , which is beneficial to the input and output of current.

[0062] In the embodiment of the present invention, the material of the ohmic contact layer 6 is Ni (nickel), and the thickness of the ohmic contact layer 6 is in the range of 60 nm to 70 nm.

[0063] In an embodiment of the present invention, the cathode 9 is formed by stacking Ti (titanium), Ni and Ag (silver) in sequence from bottom to top. Among them, Ti has good adhesion. Ni has good electrical conductivity and high hardness, which can further enhance the conductivity between metals and provide a stable support. Ag has excellent electrical conductivity and extremely low resistivity. The cathode 9 structure of titanium-nickel-silver can effectively optimize the performance, mechanical strength and chemical stability of the device.

[0064] In the embodiment of the present invention, the numerous depressions and protrusions formed by the multiple, spaced-apart moth-eye-shaped sub-passivation layers included in the moth-eye array passivation layer 4 can effectively reduce light reflection. Furthermore, the sub-passivation layers are made of alkaline-earth-doped silicon oxide. The combination of the alkaline-earth-doped silicon oxide and the microstructure of the moth-eye array passivation layer 4 further reduces light reflection and improves light utilization. Furthermore, based on the properties of alkaline-earth-doped silicon oxide, the moth-eye-shaped sub-passivation layers in the moth-eye array passivation layer 4 can be formed by reflow during the preparation of the Schottky contact layer 5 and the ohmic contact layer 6, making the preparation of the moth-eye array passivation layer 4 simpler, more efficient, and less costly.

[0065] In an embodiment of the present invention, a method for preparing a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode is also provided, see Figure 2 , Figure 21 is a flow chart of a method for preparing a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode provided by an embodiment of the present invention. The preparation method specifically includes the following steps:

[0066] Step S201 , selecting a substrate 1 .

[0067] In the embodiment of the present invention, the material of the selected substrate 1 is SiC, the thickness can be 350 μm, the concentration can be 5×10 18 cm -3 Specifically, the substrate 1 may be an n+ type SiC substrate.

[0068] Step S202 : growing an epitaxial layer on the substrate 1 .

[0069] In the embodiment of the present invention, the epitaxial layer may be grown by processes such as PECVD (Plasma Enhanced Chemical Vapor Deposition) or magnetron sputtering.

[0070] In the embodiment of the present invention, the epitaxial layer includes a first epitaxial layer 2 and a second epitaxial layer 3 superimposed on the first epitaxial layer 2. The specific growth process of the epitaxial layer is as follows:

[0071] See also Figure 3 (a) in Figure 3 This is a schematic diagram of the preparation process of a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode provided by an embodiment of the present invention. A first epitaxial layer 2 is grown on a substrate 1 by a process such as PECVD or magnetron sputtering. The material of the first epitaxial layer 2 can be SiC, the thickness can range from 1.5μm to 2μm, and the concentration can range from 1×10 16 cm -3 ~2×10 16 cm -3 Specifically, the first epitaxial layer 2 may be an n-type SiC epitaxial layer.

[0072] See also Figure 3 In (b), a second epitaxial layer 3 is grown on the first epitaxial layer 2 by PECVD or magnetron sputtering. The material of the second epitaxial layer 3 can be Ga2O3, the thickness can be in the range of 0.2μm to 0.5μm, and the concentration can be in the range of 1×10 16 cm -3 ~2×10 16 cm -3 Specifically, the second epitaxial layer 3 may be an n-type Ga2O3 epitaxial layer.

[0073] In step S203 , alkaline earth doped silicon oxide is deposited on the entire surface of the epitaxial layer, and the entire surface of the alkaline earth doped silicon oxide is etched by an etching process to form an initial passivation layer array; the initial passivation layer array includes a plurality of alkaline earth doped silicon oxide blocks arranged at intervals.

[0074] See also Figure 3 In step (c), alkaline earth doped silicon oxide is first deposited on the entire surface of the epitaxial layer using LPCVD (Low Pressure Chemical Vapor Deposition) technology. The thickness of the entire surface of alkaline earth doped silicon oxide ranges from 500 nm to 1000 nm.

[0075] See also Figure 3 In step (d), a photolithography and etching process is used to etch downward from the entire top surface of the alkaline-earth-doped silicon oxide to create windows to form an initial passivation layer array. The width of the windows ranges from 500 nm to 800 nm, and the spacing ranges from 500 nm to 800 nm. That is, the spacing between the multiple spaced alkaline-earth-doped silicon oxide blocks in the initial passivation layer array ranges from 500 nm to 800 nm, and the width of each alkaline-earth-doped silicon oxide block ranges from 500 nm to 800 nm. Specifically, the window pattern can be hexagonal, circular, or the like.

[0076] In step S204 , a Schottky contact layer 5 is deposited on the upper surface of the epitaxial layer except for the alkaline earth doped silicon oxide block, and an ohmic contact layer 6 is deposited on the lower surface of the substrate 1 .

[0077] In the embodiment of the present invention, electron beam evaporation or magnetron sputtering process can be used to perform full-surface metal deposition on the front and back of the device, that is, full-surface metal deposition is performed on the upper surface of the alkaline earth doped silicon oxide block and the epitaxial layer and the lower surface of the substrate 1, and an ohmic contact layer 6 is formed on the lower surface of the substrate 1. Figure 3 (e) in .

[0078] After annealing, the metal in the area of ​​the epitaxial layer except the alkaline earth doped silicon oxide block is retained to form a Schottky contact layer 5. Figure 3 (f) in.

[0079] In the embodiment of the present invention, the material of the Schottky contact layer 5 is Pt, and the thickness of the Schottky contact layer 5 is in the range of 60 nm to 70 nm. The material of the ohmic contact layer 6 is Ni, and the thickness of the ohmic contact layer 6 is in the range of 60 nm to 70 nm.

[0080] In step S205 , the Schottky contact layer 5 and the ohmic contact layer 6 are annealed by a thermal annealing process. At the same time, the alkaline earth doped silicon oxide block treated by the thermal annealing process is reflowed to form a moth-eye shaped sub-passivation layer; multiple sub-passivation layers form a moth-eye array passivation layer 4 .

[0081] In the embodiment of the present invention, a rapid thermal annealing process is used to anneal the Schottky contact layer 5 and the ohmic contact layer 6. The annealing conditions are 1000° C. for 180 seconds in an inert gas atmosphere. The inert gas may be nitrogen or helium.

[0082] Each alkaline earth doped silicon oxide block treated by the thermal annealing process will reflow to form a moth-eye shaped sub-passivation layer, thereby obtaining a moth-eye array passivation layer 4, see Figure 3 (f) in the figure obtains the light subtraction and reflection enhancement capability, further improving the photoelectric detection performance of the device.

[0083] In one implementation, after the annealing treatment, before proceeding to the next step of depositing metal on the upper surface of the Schottky contact layer 5 to form the anode 7, the preparation method further includes:

[0084] The ohmic contact layer 6 is made transparent using a chemical solution, and the metal residue on the upper surface of the moth-eye array passivation layer 4 is removed. The volume ratio of nitric acid, BOE (Buffered Oxide Etch) and deionized water in the chemical solution is 1:1:5.

[0085] In the embodiment of the present invention, the purpose of making the ohmic contact layer 6 transparent and removing the metal residue on the upper surface of the moth-eye array passivation layer 4 is to reduce light reflection and improve light transmission performance.

[0086] Step S206 , performing metal deposition on the upper surface of the Schottky contact layer 5 to form an anode 7 .

[0087] In the embodiment of the present invention, electron beam evaporation or magnetron sputtering is used to deposit Al metal on the entire front surface of the device, with a thickness ranging from 500nm to 1000nm. Then, photolithography and etching processes are used to etch away the Al metal on the surface of the sub-passivation layer from the upper surface of the deposited Al metal downward, leaving the Al metal on the upper surface of the Schottky contact layer 5 to form the anode 7. Figure 3 (g) in.

[0088] Step S207 , forming a passivation protection layer 8 on the upper surfaces of the moth-eye array passivation layer 4 and the anode 7 .

[0089] In the embodiment of the present invention, a SiyNx anti-reflection surface passivation protective layer can be formed on the photosensitive window on the surface of the device by using PECVD and photolithography etching processes. Figure 3 (h) in.

[0090] Step S208 : depositing a cathode 9 on the lower surface of the ohmic contact layer 6 .

[0091] In the embodiment of the present invention, the device is flipped so that the lower surface of the ohmic contact layer 6 faces upward, and then 200nm of Ti, 200nm of Ni and 1000nm of Ag are sequentially deposited on the lower surface of the ohmic contact layer 6 using an electron beam evaporation process to form a cathode 9, which can also serve as a back reflection layer to increase the light utilization rate of the device. Figure 3 (i) in .

[0092] In an embodiment of the present invention, the moth-eye array passivation layer 4 is formed by reflowing while annealing the Schottky contact layer 5 and the ohmic contact layer 6 using a thermal annealing process during the metal self-alignment process of the device. No additional processing steps are required, making the preparation of the moth-eye array passivation layer 4 simpler, more efficient, and less expensive. This solves the problems of difficult anti-reflection structure design and complex preparation processes in existing devices. The numerous depressions and protrusions formed by the multiple spaced moth-eye-shaped sub-passivation layers included in the moth-eye array passivation layer 4 can effectively reduce light reflection. The sub-passivation layers are made of alkaline-earth-doped silicon oxide. The combination of alkaline-earth-doped silicon oxide and the microstructure of the moth-eye array passivation layer 4 can further reduce light reflection and improve light utilization.

[0093] It should be noted that the terms "first," "second," and the like are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in sequences other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention.

[0094] In the description of this specification, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features 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 or characteristics described can be combined in any suitable 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.

[0095] 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 viewing the drawings and the disclosed content. In the description of the present invention, the word "comprising" does not exclude other components or steps, "one" or "a" does not exclude multiple situations, and "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0096] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0097] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0098] 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 homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode, characterized in that: The isotype silicon carbide gallium oxide heterojunction ultraviolet photodiode comprises: Substrate; the material of the substrate is SiC; An epitaxial layer superimposed on the substrate; the epitaxial layer includes a first epitaxial layer and a second epitaxial layer superimposed on the first epitaxial layer; the material of the first epitaxial layer is SiC; the material of the second epitaxial layer is Ga2O3; a moth-eye array passivation layer superimposed on the epitaxial layer; the moth-eye array passivation layer comprises a plurality of moth-eye-shaped sub-passivation layers arranged at intervals; the material of the sub-passivation layers is alkaline earth-doped silicon oxide; a Schottky contact layer superimposed on the upper surface of the epitaxial layer except the sub-passivation layer; an anode stacked on the Schottky contact layer; a passivation protection layer superimposed on the moth-eye array passivation layer and the anode; an ohmic contact layer superimposed below the substrate; A cathode is stacked below the ohmic contact layer.

2. The isotype silicon carbide gallium oxide heterojunction ultraviolet photodiode according to claim 1, characterized in that: The thickness of the first epitaxial layer ranges from 1.5 μm to 2 μm; the thickness of the second epitaxial layer ranges from 0.2 μm to 0.5 μm.

3. The isotype silicon carbide gallium oxide heterojunction ultraviolet photodiode according to claim 1, characterized in that: The thickness of the moth-eye array passivation layer ranges from 500 nm to 1000 nm.

4. The isotype silicon carbide gallium oxide heterojunction ultraviolet photodiode according to claim 1, characterized in that: The material of the ohmic contact layer is Ni; the thickness of the ohmic contact layer ranges from 60 nm to 70 nm.

5. The isotype silicon carbide gallium oxide heterojunction ultraviolet photodiode according to claim 1, characterized in that: The material of the Schottky contact layer is Pt; the thickness of the Schottky contact layer ranges from 60 nm to 70 nm.

6. The isotype silicon carbide gallium oxide heterojunction ultraviolet photodiode according to claim 1, characterized in that: The material of the anode is Al; the thickness of the anode ranges from 500nm to 1000nm.

7. The isotype silicon carbide gallium oxide heterojunction ultraviolet photodiode according to claim 1, characterized in that: The cathode is formed by stacking Ti, Ni and Ag in sequence from bottom to top.

8. A method for preparing a homogeneous silicon carbide gallium oxide heterojunction ultraviolet photodiode, characterized in that: The preparation method comprises: Selecting a substrate; the material of the substrate is SiC; Growing an epitaxial layer on the substrate; the epitaxial layer includes a first epitaxial layer and a second epitaxial layer superimposed on the first epitaxial layer; the material of the first epitaxial layer is SiC; the material of the second epitaxial layer is Ga2O3; Depositing alkaline earth-doped silicon oxide on the entire surface of the epitaxial layer, and etching the entire surface of the alkaline earth-doped silicon oxide through an etching process to form an initial passivation layer array; the initial passivation layer array includes a plurality of alkaline earth-doped silicon oxide blocks arranged at intervals; Depositing a Schottky contact layer on the upper surface of the epitaxial layer except for the alkaline earth doped silicon oxide block, and depositing an ohmic contact layer on the lower surface of the substrate; Annealing the Schottky contact layer and the ohmic contact layer using a thermal annealing process, and simultaneously reflowing the alkaline earth-doped silicon oxide blocks treated by the thermal annealing process to form moth-eye-shaped sub-passivation layers, wherein a plurality of the sub-passivation layers form a moth-eye array passivation layer; Depositing metal on the upper surface of the Schottky contact layer to form an anode; forming a passivation protection layer on the moth-eye array passivation layer and the upper surface of the anode; A cathode is deposited on the lower surface of the ohmic contact layer.

9. The preparation method according to claim 8, characterized in that Before depositing metal on the upper surface of the Schottky contact layer to form an anode, the preparation method further includes: The ohmic contact layer is transparentized using a liquid chemical, and the metal residue on the upper surface of the moth-eye array passivation layer is removed. The volume ratio of nitric acid, BOE and deionized water in the liquid chemical is 1:1:5.

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