Semiconductor graphene-silicon carbide diode and preparation method and application thereof

Abstract

The application provides a semiconductor graphene-silicon carbide diode and a preparation method and application thereof, and belongs to the technical field of semiconductor materials and devices. The semiconductor graphene-silicon carbide diode comprises a silicon carbide substrate and a semiconductor graphene layer. Specifically, the semiconductor graphene layer is directly formed on the surface of the silicon carbide substrate through an epitaxial growth process, and the semiconductor graphene layer and the silicon carbide substrate are combined through a covalent bond. The semiconductor graphene layer and the silicon carbide substrate form a heterojunction in the direction of the vertical combination surface, and the semiconductor graphene layer and the silicon carbide substrate respectively constitute an anode and a cathode of the semiconductor graphene-silicon carbide diode, and the semiconductor graphene-silicon carbide diode is a vertical diode.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials and devices, and in particular to a semiconductor graphene-silicon carbide diode, its preparation method, and its applications. Background Technology

[0002] As integrated circuit process nodes continue to approach physical limits, the traditional CMOS technology's reliance on shrinking dimensions to increase integration density faces severe challenges. When transistor sizes shrink to the nanoscale, problems such as quantum tunneling, short-channel effects, and mobility degradation become increasingly prominent, leading to decreased device performance. Against this backdrop, two-dimensional materials, represented by graphene, demonstrate significant development potential in the integrated circuit field due to their unique physical properties. Graphene's high carrier saturation velocity, high carrier mobility, and excellent thermal conductivity make it a promising candidate for applications in ultra-high frequency and ultra-high speed electronic devices.

[0003] However, graphene is a zero-bandgap semiconductor material, a characteristic that results in a low rectification ratio (typically less than 100) for graphene-based diodes, making it impossible to achieve the complete shutdown required by digital logic circuits and severely limiting its application in traditional computing. To overcome these problems, related technologies have attempted to combine graphene with other semiconductor materials to form heterojunctions for diode construction. However, whether forming heterojunctions with silicon or other two-dimensional materials, the interface quality (such as Schottky barrier height and defect state density) is difficult to precisely control and unify, directly affecting the device's performance and uniformity. Simultaneously, the fabrication of high-quality monolayer graphene (such as through chemical vapor deposition) and non-destructive transfer techniques are costly and prone to introducing wrinkles, contamination, and defects, affecting device yield and reliability. Furthermore, graphene lacks stable doping techniques, making it difficult to achieve stable, controllable, and higher concentrations of electrical doping, limiting the realization of graphene PN junction diodes.

[0004] Therefore, how to obtain diodes with high interface quality and superior rectification performance while overcoming the zero bandgap defect of graphene has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of this, to solve at least one technical problem in related technologies and other aspects, the present invention proposes a semiconductor graphene-silicon carbide diode. This semiconductor graphene-silicon carbide diode includes a silicon carbide substrate and a semiconductor graphene layer. Specifically, the semiconductor graphene layer is directly formed on the surface of the silicon carbide substrate through an epitaxial growth process, and the semiconductor graphene layer and the silicon carbide substrate are bonded together by covalent bonds. The semiconductor graphene layer and the silicon carbide substrate form a heterojunction in the direction perpendicular to the bonding surface. The semiconductor graphene layer and the silicon carbide substrate respectively constitute the anode and cathode of the semiconductor graphene-silicon carbide diode, and the semiconductor graphene-silicon carbide diode is a vertical diode.

[0006] According to an embodiment of the present invention, when the semiconductor graphene-silicon carbide diode receives a forward bias voltage through the silicon carbide substrate and the semiconductor graphene layer, the Schottky barrier on the silicon carbide substrate side is lowered, so that electrons from the silicon carbide substrate can pass through the Schottky barrier and be injected into the semiconductor graphene; when the semiconductor graphene-silicon carbide diode receives a reverse bias voltage through the silicon carbide substrate and the semiconductor graphene layer, the Schottky barrier on the silicon carbide substrate side is raised, so as to realize the reverse rectification function of the semiconductor graphene-silicon carbide diode.

[0007] According to an embodiment of the present invention, a built-in electric field and a space charge region are formed at the interface of the heterojunction by utilizing the work function difference between the semiconductor graphene layer and the silicon carbide substrate.

[0008] According to an embodiment of the present invention, the band gap of the semiconductor graphene layer is 0.6 eV to 1 eV.

[0009] According to an embodiment of the present invention, the rectification ratio of the semiconductor graphene-silicon carbide diode is not less than 10 in the voltage range of -10V to 10V. 9 .

[0010] According to an embodiment of the present invention, the forward voltage drop of the semiconductor graphene-silicon carbide diode is 0.2V~0.5V, and the operating temperature of the semiconductor graphene-silicon carbide diode is 280K~400K.

[0011] In another aspect of the present invention, a method for fabricating the aforementioned semiconductor graphene-silicon carbide diode is also proposed, comprising: firstly providing a silicon carbide substrate; then epitaxially growing a semiconductor graphene material on the surface of the silicon carbide substrate, such that the semiconductor graphene material and the surface of the silicon carbide substrate are connected by covalent bonds; then exposing the semiconductor graphene material and the silicon carbide substrate to pattern the semiconductor graphene material to form an anode pattern; finally etching the exposed semiconductor graphene material to form a semiconductor graphene layer with an anode pattern, thereby obtaining a semiconductor graphene-silicon carbide diode.

[0012] According to an embodiment of the present invention, the exposure method is photolithography or electron beam exposure.

[0013] According to an embodiment of the present invention, the etching method is physical etching or chemical etching.

[0014] In another aspect of the invention, a half-bridge rectifier circuit or a full-bridge rectifier circuit is also proposed, including the aforementioned semiconductor graphene-silicon carbide diode.

[0015] According to an embodiment of the present invention, a silicon carbide substrate and a semiconductor graphene layer are the cathode and anode of a semiconductor graphene-silicon carbide diode, respectively, forming a heterojunction at the perpendicular junction. This vertical structure allows for longitudinal carrier transport, resulting in a shorter path and reducing on-resistance. Specifically, the semiconductor graphene layer is directly formed on the surface of the silicon carbide substrate through epitaxial growth, and the two are bonded together by covalent bonds. This feature ensures high quality at the heterojunction interface, avoids wrinkles, contamination, and defects introduced by material transfer processes, and provides good controllability and uniformity of the Schottky barrier and space charge region at the interface. The silicon carbide substrate, as the cathode, provides mechanical support and a conductive channel, while the semiconductor graphene layer, as the anode, provides rectification. The covalent bonds formed by epitaxial growth ensure interface quality, and the vertical structure shortens the carrier transport path. These features work together to enable the semiconductor graphene-silicon carbide diode to achieve high rectification performance and device uniformity. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the semiconductor graphene-silicon carbide diode in an embodiment of the present invention;

[0017] Figure 2 This is a Raman test result diagram of the semiconductor graphene in Embodiment 1 of the present invention;

[0018] Figure 3 This is a graph showing the current-voltage characteristic of a semiconductor graphene-silicon carbide diode at room temperature between -10V and 10V in Embodiment 1 of the present invention.

[0019] Figure 4 This is a graph showing the current-voltage characteristic of the semiconductor graphene-silicon carbide diode at room temperature between -1V and 1V in Embodiment 1 of the present invention.

[0020] Figure 5 This is a graph showing the current-voltage characteristic of a semiconductor graphene-silicon carbide diode in a 300-400K environment between -10V and 10V in Embodiment 1 of the present invention.

[0021] Figure 6The output waveforms of the half-bridge rectifier circuit in Application Example 1 of this invention under 3V sine wave input at different frequencies are shown, where (a) has a frequency of 50Hz, (b) has a frequency of 500Hz, (c) has a frequency of 5kHz, and (d) has a frequency of 10kHz. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0023] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0025] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention.

[0027] Similarly, to simplify the invention and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, 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.

[0028] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0029] In the process of realizing this invention, it was discovered that the zero bandgap characteristic of traditional graphene is the fundamental reason for its relatively low diode switching performance. Furthermore, constructing heterojunctions with other semiconductor materials using graphene is limited by the difficulty in controlling interface quality and the complexity of the process. Semiconductor graphene overcomes the lack of a bandgap in ordinary graphene and possesses a bandgap of 5500 cm⁻¹. -1 V -1 s -1 The above-mentioned intrinsic carrier mobility, excellent thermal stability, and good processability are advantages, and at the same time, epitaxial semiconductor graphene with a band gap of over 0.6 eV and high room temperature mobility can be prepared in silicon carbide.

[0030] Therefore, this invention proposes to directly construct a semiconductor graphene-silicon carbide diode using semiconductor graphene material epitaxially grown on a silicon carbide substrate. By utilizing the band gap characteristic of semiconductor graphene itself, the zero band gap defect can be overcome. At the same time, by utilizing the characteristic that semiconductor graphene and silicon carbide are bonded by covalent bonds during epitaxial growth on the silicon carbide substrate, a high-quality heterojunction interface can be obtained. Thus, a vertical diode with superior rectification performance can be formed without additional material transfer processes.

[0031] Figure 1 This is a schematic diagram of the structure of a semiconductor graphene-silicon carbide diode in an embodiment of the present invention.

[0032] This invention proposes a semiconductor graphene-silicon carbide diode. For example... Figure 1 As shown, the semiconductor graphene-silicon carbide diode includes a silicon carbide substrate and a semiconductor graphene layer. Specifically, the semiconductor graphene layer is directly formed on the surface of the silicon carbide substrate through an epitaxial growth process, and the semiconductor graphene layer and the silicon carbide substrate are bonded together by covalent bonds. The semiconductor graphene layer and the silicon carbide substrate form a heterojunction in the direction perpendicular to the bonding surface. The semiconductor graphene layer and the silicon carbide substrate respectively constitute the anode and cathode of the semiconductor graphene-silicon carbide diode, making the semiconductor graphene-silicon carbide diode a vertical diode.

[0033] According to an embodiment of the present invention, a silicon carbide substrate and a semiconductor graphene layer are the cathode and anode of a semiconductor graphene-silicon carbide diode, respectively, forming a heterojunction in the direction perpendicular to the bonding surface. This vertical structure allows carriers to transport along the longitudinal direction, resulting in a shorter path and reducing on-resistance. Specifically, the semiconductor graphene layer is directly formed on the surface of the silicon carbide substrate through an epitaxial growth process, and the two are bonded together by covalent bonds. This feature ensures higher quality at the heterojunction interface, avoids wrinkles, contamination, and defects introduced by material transfer processes, and provides better controllability and uniformity of the Schottky barrier and space charge region at the interface. The silicon carbide substrate, as the cathode, provides mechanical support and a conductive channel, while the semiconductor graphene layer, as the anode, provides rectification. The covalent bonds formed by epitaxial growth ensure interface quality, and the vertical structure shortens the carrier transport path. These features work together to enable the semiconductor graphene-silicon carbide diode to achieve high rectification performance and device uniformity.

[0034] In this invention, the term "vertical diode" refers to a semiconductor graphene-silicon carbide diode structure in which current flows perpendicular to the substrate surface (i.e., longitudinally). In this invention, the semiconductor graphene layer is located on the upper surface of the silicon carbide substrate, and the two form a heterojunction in the direction perpendicular to the interface. Current flows vertically downwards from the top semiconductor graphene layer through the heterojunction interface to the bottom silicon carbide substrate. Compared to lateral structures, vertical diodes have shorter carrier transport paths, which helps reduce on-resistance and switching losses. They also more fully utilize the higher carrier mobility of semiconductor graphene and the higher saturation drift velocity of silicon carbide, making them suitable for high-current and high-power applications.

[0035] In some specific embodiments, the silicon carbide substrate type is 4H-SiC or 6H-SiC.

[0036] In some more specific embodiments, 4H-SiC and 6H-SiC are relatively mature crystal forms of silicon carbide materials, capable of maintaining stable electrical properties over a wide temperature range. 4H-SiC has a high electron mobility, typically greater than 800 cm⁻¹. 2 V -1 s -1Furthermore, it possesses a critical breakdown field strength of 3.5 MV / cm, making it suitable for higher frequency and higher speed applications, such as RF devices and power converters commonly used in 5G base stations. 6H-SiC has a more stable lattice structure and a high thermal conductivity of 4.9 W / cm·K, making it suitable for high-temperature and high-power applications such as electric vehicles and photovoltaic inverters. Both of these silicon carbide crystalline forms can be used to prepare high-quality semiconductor graphene layers on their surfaces via epitaxial growth. The two exhibit good lattice matching, which is beneficial for obtaining heterojunction interfaces with low defect density. Simultaneously, both silicon carbide substrates have relatively mature processing technologies in the semiconductor manufacturing field, facilitating compatibility with existing semiconductor process flows.

[0037] In some specific embodiments, the superior performance of this semiconductor graphene-silicon carbide diode relies on the excellent interface quality between the silicon carbide substrate and the semiconductor graphene layer. Because the semiconductor graphene is directly epitaxially grown on the silicon carbide substrate, there are covalent bonds between the two, and the lattice parameters of silicon carbide and graphene are similar, resulting in interface state matching between the two and making it difficult for defects and impurities to occur. Therefore, the semiconductor graphene-silicon carbide diode has excellent rectification performance and stability.

[0038] In some specific embodiments, the semiconductor graphene-silicon carbide diode proposed in this invention has good signal processing capabilities, can significantly distinguish between conduction and off states, and reduce erroneous operations.

[0039] According to an embodiment of the present invention, when the semiconductor graphene-silicon carbide diode receives a forward bias voltage through the silicon carbide substrate and the semiconductor graphene layer, the Schottky barrier on the silicon carbide substrate side is lowered, so that electrons from the silicon carbide substrate can pass through the Schottky barrier and be injected into the semiconductor graphene; when the semiconductor graphene-silicon carbide diode receives a reverse bias voltage through the silicon carbide substrate and the semiconductor graphene layer, the Schottky barrier on the silicon carbide substrate side is raised, so as to realize the reverse rectification function of the semiconductor graphene-silicon carbide diode.

[0040] According to an embodiment of the present invention, when a forward bias is applied, the Schottky barrier on the silicon carbide substrate side decreases, allowing electrons in the silicon carbide substrate to overcome the barrier and inject into the semiconductor graphene layer, forming a larger forward current and thus achieving a lower on-state voltage drop. When a reverse bias is applied, the Schottky barrier on the silicon carbide substrate side increases, making it difficult for electrons to overcome the barrier, with only a small reverse saturation current passing through, thereby achieving reverse cutoff. Based on the different response characteristics of the Schottky barrier formed between the semiconductor graphene layer and the silicon carbide substrate under forward and reverse bias, the semiconductor graphene-silicon carbide diode possesses unidirectional conductivity, effectively achieving rectification. Simultaneously, due to the higher barrier under reverse bias, the reverse leakage current is smaller, which helps reduce the static power consumption of the semiconductor graphene-silicon carbide diode.

[0041] In some specific embodiments, the reverse leakage current of the semiconductor graphene-silicon carbide diode is at the picoampere level, which reduces the static power consumption of the semiconductor graphene-silicon carbide diode, reduces energy waste caused by leakage current, and means that the semiconductor graphene-silicon carbide diode has low self-heating, reducing the risk of performance degradation caused by overheating and improving the reliability of the semiconductor graphene-silicon carbide diode.

[0042] According to an embodiment of the present invention, a built-in electric field and a space charge region are formed at the interface of the heterojunction by utilizing the work function difference between the semiconductor graphene layer and the silicon carbide substrate.

[0043] According to embodiments of the present invention, since semiconductor graphene and silicon carbide have different work functions, electrons transfer from the side with the lower work function to the side with the higher work function after they come into contact, until the Fermi levels align, thereby forming a built-in electric field and a space charge region at the interface. The presence of the built-in electric field enables the semiconductor graphene-silicon carbide diode to effectively block the passage of majority carriers under zero bias or reverse bias, which is the physical basis for realizing unidirectional conductivity. The formation of the space charge region determines the barrier height and depletion layer width of the semiconductor graphene-silicon carbide diode, directly affecting the reverse breakdown voltage and forward conduction characteristics. By utilizing the natural difference in work functions between the two to form a built-in electric field, no additional doping or interface modification processes are required, simplifying the semiconductor graphene-silicon carbide diode fabrication process, while ensuring the uniformity and controllability of the electrical characteristics at the interface.

[0044] According to an embodiment of the present invention, the band gap of the semiconductor graphene layer is 0.6eV to 1eV, preferably 0.6eV to 0.8eV.

[0045] According to embodiments of the present invention, the semiconductor graphene has a band gap of 0.6 eV to 1 eV, which distinguishes it from conventional graphene with zero band gap, enabling effective current turn-off. Within this band gap range, the semiconductor graphene possesses both sufficient carrier excitation efficiency at room temperature to ensure forward conduction current and a high on / off ratio to achieve reverse cutoff function.

[0046] In some specific embodiments, this bandgap range allows a suitable Schottky barrier height to be formed between the semiconductor graphene layer and the silicon carbide substrate, which avoids an increase in on-state voltage drop due to an excessively high barrier or an increase in reverse leakage current due to an excessively low barrier, thus facilitating the achievement of superior rectification performance.

[0047] In some more specific embodiments, compared to the forward voltage drop of a conventional diode of 0.6-0.7V, this semiconductor graphene-silicon carbide diode reduces energy loss, improves system efficiency, and can be applied to low-voltage applications.

[0048] According to an embodiment of the present invention, the rectification ratio of the semiconductor graphene-silicon carbide diode is not less than 10 in the voltage range of -10V to 10V. 9 .

[0049] According to embodiments of the present invention, the semiconductor graphene-silicon carbide diode belongs to the Schottky diode category, and its turn-on voltage is mainly affected by the barrier height between silicon carbide and semiconductor graphene. Because semiconductor graphene has high carrier mobility, its forward current is high; because silicon carbide is a wide bandgap semiconductor, its intrinsic leakage current is also low, resulting in a low reverse current; simultaneously, because the semiconductor graphene layer epitaxially grown on silicon carbide has excellent interface quality with low interface defects, the semiconductor graphene-silicon carbide diode possesses a high rectification ratio. Furthermore, both semiconductor graphene and silicon carbide have excellent thermal conductivity, and silicon carbide is a wide bandgap semiconductor, enabling the semiconductor graphene-silicon carbide diode to operate in high-temperature environments above 100°C.

[0050] In some specific embodiments, the rectification ratio is not less than 10. 9 This means that there is a significant order of magnitude difference between the current in the forward-conducting state and the current in the reverse-blocking state of the graphene-silicon carbide diode, demonstrating its excellent unidirectional conductivity. The high rectification ratio ensures that the graphene-silicon carbide diode can effectively distinguish between the on and off states in the rectifier circuit, reducing signal distortion and energy loss. Furthermore, the high rectification ratio is maintained over a wide voltage range of -10V to 10V, indicating that the graphene-silicon carbide diode has good voltage tolerance and stable rectification characteristics, making it suitable for practical applications under various operating voltage conditions.

[0051] In some more specific embodiments, the higher mobility and lower capacitance of semiconductor graphene, along with the higher saturation drift velocity of silicon carbide, enable the semiconductor graphene-silicon carbide diode to have a higher rectification ratio.

[0052] In this invention, the term "rectification ratio" means the ratio of the reverse DC resistance to the forward DC resistance under DC operating conditions.

[0053] In some more specific embodiments, annealing the grown semiconductor graphene at 400°C to 600°C in a vacuum environment is beneficial to improving the interface quality.

[0054] According to an embodiment of the present invention, the forward voltage drop of the semiconductor graphene-silicon carbide diode is 0.2V~0.5V, and the operating temperature of the semiconductor graphene-silicon carbide diode is 280K~400K.

[0055] According to embodiments of the present invention, due to the high conductivity of semiconductor graphene, the on-resistance and switching loss of semiconductor graphene-silicon carbide diode can be reduced. The lower on-state voltage drop means that the semiconductor graphene-silicon carbide diode has less energy loss during forward conduction, which is beneficial to reducing its power consumption and heat generation, and is suitable for low-voltage and low-power application scenarios.

[0056] According to embodiments of the present invention, due to the wide bandgap characteristics of the silicon carbide substrate, which have high breakdown field strength and good thermal stability, and the high temperature resistance of the semiconductor graphene itself, the semiconductor graphene-silicon carbide diode can operate stably at temperatures ranging from 280K to 400K, which also indicates that it can maintain normal rectification function over a wide temperature range.

[0057] In some specific embodiments, the wide operating temperature range makes the semiconductor graphene-silicon carbide diode suitable for more demanding application environments such as higher temperatures and higher power.

[0058] In another aspect of the present invention, a method for fabricating the aforementioned semiconductor graphene-silicon carbide diode is also proposed, comprising: firstly providing a silicon carbide substrate; then epitaxially growing a semiconductor graphene material on the surface of the silicon carbide substrate, such that the semiconductor graphene material and the surface of the silicon carbide substrate are connected by covalent bonds; then exposing the semiconductor graphene material and the silicon carbide substrate to pattern the semiconductor graphene material to form an anode pattern; finally etching the exposed semiconductor graphene material to form a semiconductor graphene layer with an anode pattern, thereby obtaining a semiconductor graphene-silicon carbide diode.

[0059] According to embodiments of the present invention, the epitaxial growth step allows semiconductor graphene material to be directly formed on the surface of a silicon carbide substrate, with the two connected by covalent bonds. This ensures high quality at the heterojunction interface and avoids wrinkles, contamination, and defects introduced by material transfer processes, thus improving the uniformity and yield of the semiconductor graphene-silicon carbide diode. The exposure and etching steps enable patterning of the semiconductor graphene layer, precisely defining the size and shape of the anode, making the fabrication of the semiconductor graphene-silicon carbide diode compatible with traditional semiconductor planar processes. The overall fabrication process does not require complex material transfer and doping processes, making the steps relatively simple and beneficial for reducing manufacturing costs and improving production efficiency.

[0060] According to an embodiment of the present invention, the exposure method is photolithography or electron beam exposure.

[0061] According to embodiments of the present invention, photolithography and electron beam exposure are relatively mature patterning technologies in the semiconductor manufacturing field, possessing high precision and controllability. Photolithography is suitable for large-area and more efficient patterning processes, facilitating mass production; electron beam exposure has high resolution, suitable for the preparation of fine patterns. Both exposure methods can achieve precise control over the pattern of the semiconductor graphene layer, ensuring the consistency and accuracy of the anode size and shape, which is beneficial for obtaining semiconductor graphene-silicon carbide diodes with uniform performance.

[0062] According to an embodiment of the present invention, the etching method is physical etching or chemical etching.

[0063] According to embodiments of the present invention, physical etching (such as ion beam etching and plasma etching) and chemical etching (such as reactive ion etching) are both mature pattern transfer technologies in the semiconductor manufacturing field. They can accurately remove the exposed semiconductor graphene material after exposure while retaining the anode pattern. Both etching methods have high etching selectivity and dimensional control precision, which can ensure the fidelity and edge quality of the semiconductor graphene layer pattern, avoid performance degradation of semiconductor graphene-silicon carbide diodes due to etching residue or over-etching, and help ensure the rectification performance and uniformity of semiconductor graphene-silicon carbide diodes.

[0064] In another aspect of the invention, a half-bridge rectifier circuit or a full-bridge rectifier circuit is also proposed, including the aforementioned semiconductor graphene-silicon carbide diode.

[0065] According to embodiments of the present invention, the semiconductor graphene-silicon carbide diode possesses a high rectification ratio and low reverse leakage current, enabling the rectifier circuit to achieve efficient current conduction in both the positive and negative half-cycles, resulting in a smoother DC output. The low on-state voltage drop of this semiconductor graphene-silicon carbide diode helps reduce the conduction losses of the rectifier circuit and improves the overall energy conversion efficiency. The wide operating temperature range of this semiconductor graphene-silicon carbide diode allows the rectifier circuit to maintain stable rectified output over a wide range of ambient temperature variations, making it suitable for practical applications such as power management, signal processing, and energy harvesting.

[0066] It should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are all within the scope of protection of the present invention.

[0067] Example 1

[0068] Semiconductor graphene was epitaxially grown on a silicon carbide substrate, and the specific method is as follows.

[0069] (1) Take two silicon carbide (SiC) substrates for pretreatment. Neither SiC substrate is coated with a carbon film.

[0070] (2) Stack the two SiC substrates and place them in a crucible, with the C-side and Si-side of the two SiC substrates facing each other.

[0071] (3) The crucible with two stacked SiC substrates is annealed at 900~950℃ for 20~30min under vacuum to clean the SiC substrates.

[0072] (4) Heat the crucible with two stacked SiC substrates in an argon atmosphere; heat the SiC substrates at 1250~1300℃ for 20~30min in an argon atmosphere to perform preliminary morphology aggregation.

[0073] (5) Under an argon atmosphere, the crucible with two stacked SiC substrates is heated at 1560℃~1700℃ to further grow semiconductor graphene for 50~600min, and semiconductor graphene with a band gap of 0.8eV is obtained on a SiC substrate.

[0074] Semiconductor graphene material epitaxially grown on silicon carbide using the aforementioned method was used as a sample. The semiconductor graphene material and silicon carbide substrate were exposed to pattern the anode pattern of the semiconductor graphene-silicon carbide diode; the exposed pattern was then etched to obtain the semiconductor graphene-silicon carbide diode.

[0075] Electrical performance of semiconductor graphene-silicon carbide diodes was characterized.

[0076] Figure 2 This is a Raman test result diagram of semiconductor graphene in Embodiment 1 of the present invention.

[0077] like Figure 2 As shown, at a Raman displacement of 1000 cm -1 Up to 4000cm -1 Within the range, at a Raman displacement of 1630 cm -1 In this case, there is a significant peak, which is higher than the Raman displacement of 1680 cm. -1 Near the peak, there appeared a clear characteristic peak of semiconductor graphene. The Raman spectra of semiconductor graphene differ from those of ordinary graphene. The appearance, position, and shape of the characteristic peaks indicate that semiconductor graphene material was successfully prepared on a silicon carbide substrate via epitaxial growth. This Raman test result verifies the correctness of the sample material in Example 1.

[0078] Figure 3 This is a graph showing the current-voltage characteristic curve of a semiconductor graphene-silicon carbide diode at room temperature (around 25°C) in Embodiment 1 of the present invention between -10V and 10V.

[0079] like Figure 3 As shown in the figure, the horizontal axis represents voltage, and the vertical axis represents current. The curve represents the current-voltage response characteristics of the graphene-silicon carbide diode. The curve shape shows that when a forward bias is applied, the current increases rapidly with increasing voltage, exhibiting good forward conduction characteristics. When a reverse bias is applied, even at -10V, the current remains at a low level, approximately fA to pA, exhibiting excellent reverse cutoff characteristics. This asymmetric curve shape directly proves that the graphene-silicon carbide diode has unidirectional conductivity. Specifically, its reverse leakage current is only in the fA-pA range at -10V, indicating that the graphene-silicon carbide diode has low leakage current under reverse bias, which is beneficial for reducing static power consumption; the ratio between forward and reverse current (i.e., the rectification ratio) can reach 10. 9 The above demonstrates that this semiconductor graphene-silicon carbide diode has excellent rectification efficiency, can effectively distinguish between the on and off states, and is suitable for high-precision signal processing and low-power integrated circuit applications.

[0080] Figure 4 This is a current-voltage characteristic curve of the semiconductor graphene-silicon carbide diode at room temperature between -1V and 1V in Embodiment 1 of the present invention.

[0081] like Figure 4 As shown in the figure, the horizontal axis represents voltage and the vertical axis represents current. The curve illustrates the current-voltage response behavior of the semiconductor graphene-silicon carbide diode in a low voltage range. Specifically, when the forward bias gradually increases from 0V to approximately 0.32V, the current begins to show a significant inflection point. The voltage corresponding to this inflection point is the forward voltage drop. The figure shows that the forward voltage drop of this semiconductor graphene-silicon carbide diode is approximately 0.32V, falling within the range of 0.2V to 0.5V. Compared to the forward voltage drop of approximately 0.6V to 0.7V for ordinary silicon-based diodes, the semiconductor graphene-silicon carbide diode prepared in Example 1 has a lower forward voltage drop, meaning less energy is consumed in the forward conduction state. This is beneficial for improving the energy conversion efficiency of the system and reducing the heat generated by the semiconductor graphene-silicon carbide diode itself. Furthermore, the lower forward voltage drop makes this semiconductor graphene-silicon carbide diode suitable for low-voltage power supply scenarios, such as portable electronic devices, energy harvesting systems, and low-voltage rectifier circuits, showing promising application prospects.

[0082] Figure 5 This is a graph showing the current-voltage characteristic of a semiconductor graphene-silicon carbide diode in a 300-400K environment between -10V and 10V in Embodiment 1 of the present invention.

[0083] like Figure 5As shown, as the temperature increases from 300K to 400K, the forward and reverse currents of this graphene-silicon carbide semiconductor diode do not change significantly, and the reverse leakage current remains at the pA level under all temperature conditions, with the curves essentially overlapping. This indicates that the graphene-silicon carbide semiconductor diode exhibits stable rectification characteristics over a wide temperature range of 300K to 400K, effectively resisting the impact of temperature changes on electrical performance. This excellent temperature stability is attributed to two factors: the silicon carbide substrate has a wide bandgap and high thermal conductivity, maintaining good electrical performance even at higher temperatures; and the graphene semiconductor itself also possesses good thermal stability and high carrier mobility, maintaining relatively stable conductivity under temperature variations. This makes the graphene-silicon carbide semiconductor diode suitable for demanding applications such as high-temperature, high-power-density applications.

[0084] Application Example 1

[0085] The semiconductor graphene-silicon carbide diode prepared in Example 1 was applied to a half-bridge rectifier circuit. A 3V sine wave input with a frequency of 1~100kHz was applied to the circuit, and its output performance after passing through the semiconductor graphene-silicon carbide diode half-bridge rectifier circuit was tested.

[0086] Figure 6 The output waveforms of the half-bridge rectifier circuit in Application Example 1 of this invention under 3V sine wave input at different frequencies are shown, where (a) has a frequency of 50Hz, (b) has a frequency of 500Hz, (c) has a frequency of 5kHz, and (d) has a frequency of 10kHz.

[0087] At different frequencies, the half-bridge rectifier circuit can convert AC input signals into DC output signals, with a relatively smooth and stable output waveform. Specifically, for example... Figure 6 As shown in (a), under the low-frequency condition of 50Hz, the output waveform exhibits a relatively complete half-wave rectification shape; as Figure 6 As shown in (b), under the 500Hz intermediate frequency condition, the output waveform remains stable and without significant distortion; Figure 6 As shown in (c), even at a higher frequency of 5kHz, the output waveform can still maintain a stable rectified output; as Figure 6 As shown in (d), no reverse breakdown or waveform distortion occurred even at a high frequency of 10kHz, and the output waveform maintained a stable forward rectified output. This result indicates that the rectifier circuit built using the semiconductor graphene-silicon carbide diode prepared in Example 1 has good frequency adaptability and AC rectification capability, and can achieve stable rectification function over a wide frequency range, meeting the rectification performance requirements of practical circuit applications.

[0088] Comparative Example 1

[0089] In Comparative Example 1, the method for fabricating the diode is the same as or similar to that in Example 1. Specifically, unlike Example 1, the method for epitaxially growing silicon-faced graphene on a silicon carbide substrate in Comparative Example 1 is as follows: the silicon carbide substrate is preheated and then annealed at a temperature of 1200°C; the annealed silicon carbide substrate is placed in a graphite crucible and heated to a preheated temperature of 1600°C in an inert gas atmosphere, and grown for 25 minutes in an inert gas atmosphere to form silicon-faced graphene material.

[0090] Epitaxially grown zero-bandgap silicon-faced graphene is used as the anode material for diodes.

[0091] The graphene material and silicon carbide substrate are exposed to form a graphene-silicon carbide device pattern.

[0092] The exposed pattern is etched to obtain a graphene-silicon carbide device.

[0093] The electrical performance of the graphene-silicon carbide device was characterized, and the results are recorded in Table 1 below.

[0094] Comparative Example 2

[0095] In Comparative Example 2, the method for fabricating the diode is the same as or similar to that in Example 1. Specifically, unlike Example 1, zero-bandgap graphene grown by chemical vapor deposition is used as the anode material in Comparative Example 2. The method for preparing the graphene by chemical vapor deposition is as follows.

[0096] Copper foil was annealed in a container to obtain annealed metal foil sheets. The container was filled with a mixed gas of nitrogen and hydrogen in a volume ratio of 10:1. Graphene was grown on the surface of the annealed copper foil by introducing methane into the container. The growth temperature of the graphene was 1085℃, and the growth time was 11 minutes.

[0097] The anode material is transferred to the silicon carbide surface, and the graphene material and silicon carbide substrate are exposed to form a graphene-silicon carbide device pattern.

[0098] The exposed pattern is etched to obtain a graphene-silicon carbide device.

[0099] The electrical performance of graphene-silicon carbide devices was characterized.

[0100] By comparing Example 1 with Comparative Examples 1 and 2, the electrical performance of diodes formed by combining semiconductor graphene and ordinary graphene with silicon carbide can be compared. The comparison results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As shown in Table 1, Example 1 uses epitaxially grown semiconductor graphene on silicon carbide as the anode material, and the resulting semiconductor graphene-silicon carbide diode exhibits unidirectional conductivity and a high rectification ratio. Comparative Example 1 uses epitaxially grown silicon-surface graphene as the anode material, and Comparative Example 2 uses graphene grown by chemical vapor deposition and transferred onto the silicon carbide surface; neither of these methods produces devices with unidirectional conductivity or a high rectification ratio. This comparison clearly demonstrates that ordinary graphene (including epitaxially grown silicon-surface graphene and graphene grown by chemical vapor deposition) cannot form a semiconductor graphene-silicon carbide diode with unidirectional conductivity when combined with silicon carbide. In this invention, semiconductor graphene is selected as the anode material, utilizing its 0.6 eV to 1 eV bandgap. This overcomes the fundamental problem of ineffective turn-off caused by the zero bandgap of ordinary graphene, enabling the semiconductor graphene-silicon carbide diode to achieve unidirectional conductivity and a high rectification ratio. Meanwhile, the comparison results also indirectly prove that the covalent bond interface formed between semiconductor graphene and silicon carbide substrate through epitaxial growth has high quality, while the interface defects introduced by the transfer method are one of the important reasons why the device in Comparative Example 2 does not have diode characteristics.

[0104] In summary, this invention provides a semiconductor graphene-silicon carbide diode with a simple fabrication method, low manufacturing cost, and excellent electrical performance, offering an ideal solution for the application of semiconductor graphene in the diode field. Compared to traditional graphene diodes, the semiconductor graphene-silicon carbide diode prepared by this invention exhibits a significantly higher rectification ratio and a markedly lower reverse leakage current, demonstrating significant advantages in rectification efficiency and power consumption reduction. Furthermore, the half-wave rectifier circuit fabricated using the semiconductor graphene-silicon carbide diode proposed in this invention possesses excellent AC rectification capabilities, meeting the needs of practical applications.

[0105] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A semiconductor graphene-silicon carbide diode, characterized in that, include: silicon carbide substrate; A semiconductor graphene layer is directly formed on the surface of the silicon carbide substrate through an epitaxial growth process, and the semiconductor graphene layer and the silicon carbide substrate are bonded together by covalent bonds. The semiconductor graphene layer and the silicon carbide substrate form a heterojunction in the direction perpendicular to the bonding surface. The semiconductor graphene layer and the silicon carbide substrate respectively constitute the anode and cathode of the semiconductor graphene-silicon carbide diode, and the semiconductor graphene-silicon carbide diode is a vertical diode.

2. The semiconductor graphene-silicon carbide diode according to claim 1, characterized in that, When the semiconductor graphene-silicon carbide diode receives a forward bias voltage via the silicon carbide substrate and the semiconductor graphene layer, the Schottky barrier on the silicon carbide side is reduced, so that electrons from the silicon carbide substrate pass through the Schottky barrier and are injected into the semiconductor graphene layer. When the semiconductor graphene-silicon carbide diode receives reverse bias through the silicon carbide substrate and the semiconductor graphene layer, the Schottky barrier on the silicon carbide substrate side is raised to realize the reverse rectification function of the semiconductor graphene-silicon carbide diode.

3. The semiconductor graphene-silicon carbide diode according to claim 1, characterized in that, By utilizing the work function difference between the semiconductor graphene layer and the silicon carbide substrate, a built-in electric field and a space charge region are formed at the interface of the heterojunction. The difference in work function is 0.8-1.2 eV.

4. The semiconductor graphene-silicon carbide diode according to claim 1, characterized in that, The band gap of the semiconductor graphene layer is 0.6eV~1eV.

5. The semiconductor graphene-silicon carbide diode according to claim 1, characterized in that, The rectification ratio of the semiconductor graphene-silicon carbide diode is not less than 10 in the voltage range of -10V to 10V. 9 .

6. The semiconductor graphene-silicon carbide diode according to claim 1, characterized in that, The forward voltage drop of the semiconductor graphene-silicon carbide diode is 0.2V~0.5V, and the operating temperature of the semiconductor graphene-silicon carbide diode is 280K~400K.

7. A method for fabricating a semiconductor graphene-silicon carbide diode as described in any one of claims 1 to 6, characterized in that, include: Provide silicon carbide substrates; Semiconductor graphene material is epitaxially grown on the surface of the silicon carbide substrate, and the semiconductor graphene material is covalently connected to the surface of the silicon carbide substrate. The semiconductor graphene material and the silicon carbide substrate are exposed to form an anode pattern. The exposed semiconductor graphene material is etched to form a semiconductor graphene layer with the anode pattern, thereby obtaining a semiconductor graphene-silicon carbide diode.

8. The preparation method according to claim 7, characterized in that, The exposure method is photolithography or electron beam exposure.

9. The preparation method according to claim 7, characterized in that, The etching method is either physical etching or chemical etching.

10. A half-bridge rectifier circuit or a full-bridge rectifier circuit, characterized in that, Including the semiconductor graphene-silicon carbide diode as described in any one of claims 1 to 6.

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