SiC-based semiconductor photosensitive element and preparation method thereof

Abstract

The invention belongs to the technical field of semiconductor photosensitive elements, and particularly relates to a SiC-based semiconductor photosensitive element and a preparation method thereof. According to the method, by means of combination of high-temperature pyrolysis and pulse laser assistance, C-Si bonds on the surface of SiC are activated under high-temperature assistance, and the C-Si bonds are broken through laser irradiation; and meanwhile, doping elements adsorbed on the SiC surface are embedded into 3-5 atomic layers on the SiC surface in an atomic form to form a new lattice structure, so that a bulk phase complete crystal structure is ensured, lattice distortion is avoided, defects are inhibited, the high-quality SiC-based semiconductor photosensitive element is obtained, and the light response performance of the SiC-based semiconductor photosensitive element is improved. The problems that an existing SiC-based optical element has many bulk phase defects, doping elements are uncontrollable, and the surface is difficult to dope and modify are solved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor photosensitive element technology, specifically relating to a SiC-based semiconductor photosensitive element and its preparation method. Background Technology

[0002] As a key representative of third-generation semiconductors, SiC has been widely used in high-power electronic devices, radio frequency components, and light-emitting diodes due to its high thermal conductivity, high electron mobility, excellent chemical stability, and high mechanical strength. Simultaneously, SiC is also a good ultraviolet light absorber, showing potential in optoelectronic devices and related photoinduced reaction systems. However, SiC's relatively wide bandgap results in weak absorption in the visible light band, accounting for approximately 45% of the solar spectrum; this significantly limits the expansion of SiC's applications in solar-driven scenarios.

[0003] To address the aforementioned issues, existing technologies generally employ elemental doping strategies to modulate the optical properties of SiC. The principle is to introduce impurity energy levels into the SiC band structure, effectively reducing the band gap and thus extending its photoresponse range into the visible light region. For example, reference 1: Hou. B-doped 3C-SiC nanowires with a finned microstructure for efficient visible light-driven photocatalytic hydrogen production. Nanoscale, 2015, 7, 8955. Reference 1 utilizes boron doping to construct intermediate energy levels in SiC, significantly enhancing its photoresponse intensity in the visible light region; simultaneously, it confirms that boron co-doping can significantly enhance the response intensity of SiC in the visible light region. Furthermore, some researchers have considered using elements such as aluminum and nitrogen as dopants. The introduction of these dopants can not only adjust the band structure but also modulate n-type or p-type electrical properties.

[0004] However, elemental doping can lead to uneven distribution of dopant elements in the bulk or surface of SiC, causing lattice structure distortion and increasing defects, which in turn affects the intrinsic physical and chemical properties of SiC. Summary of the Invention

[0005] To overcome the problems of bulk lattice destruction and numerous defects in the bulk or surface caused by elemental doping in the fabrication of visible-light-responsive SiC semiconductor photosensitive elements, this invention provides a SiC-based semiconductor photosensitive element and its fabrication method. This invention utilizes a combination of high-temperature pyrolysis and pulsed laser-assisted methods. Under high-temperature assistance, C-Si bonds on the SiC surface are activated, and laser irradiation breaks the C-Si bonds. Simultaneously, dopants adsorbed on the SiC surface are embedded atomically to form a new lattice structure. Elemental doping is performed only on the surface atomic layers (3 to 5 layers), thereby ensuring the integrity of the SiC bulk crystal structure, avoiding lattice distortion, suppressing defect generation, obtaining a high-quality SiC-based semiconductor photosensitive element, and improving its photoresponse performance.

[0006] The SiC-based semiconductor photosensitive element prepared by this invention not only has good visible and near-infrared light response performance, but also exhibits good electrical transport properties.

[0007] The first objective of this invention is to provide a method for fabricating a SiC-based semiconductor photosensitive element, comprising the following steps: Under a protective atmosphere, the SiC substrate is heated to 300℃~900℃ for thermal activation. Under heating conditions, a dopant source is introduced into the surface of the SiC substrate, and the surface of the SiC substrate is scanned and irradiated with a laser to induce the dopant element to embed into 3 to 5 atomic layers on the surface of the SiC substrate, thereby obtaining a SiC semiconductor photosensitive element.

[0008] It should be noted that under heating conditions, the C-Si bonds on the SiC surface are activated by thermal excitation; subsequently, under high-energy pulsed laser irradiation, the C-Si bonds on the SiC surface break; the dopants adsorbed on the SiC surface are transformed into atomic states under the action of the high-energy laser, forming new bonds with C and Si atoms in atomic form, achieving surface embedding of elements and forming a new crystal structure system. This method only performs elemental doping on 3 to 5 atomic layers on the surface of silicon carbide, without destroying the bulk crystal lattice. The embedded atoms introduce impurity energy levels between the conduction band and valence band of SiC, reducing the band gap and redshifting the absorption spectrum, thus exhibiting good absorption response in the visible and near-infrared regions.

[0009] Preferably, the heating temperature is 500℃~700℃, and the time is 0.5 hours~5 hours. The higher the heating temperature, the higher the activation degree of the C-Si bond, the easier it is to break, and the easier it is to insert dopants. The heating temperature is adjusted according to the type of dopant. For example, for dopants that are easier to insert, such as aluminum atoms, a relatively low heating temperature is selected; for dopants that are difficult to insert, a relatively high heating temperature is selected.

[0010] Preferably, the conditions for scanning irradiation of the SiC substrate surface using a laser are: laser wavelength of 532nm to 1064nm and pulse power of 1W to 5W. The main effect of laser irradiation is to break C-Si bonds; the higher the laser power and the shorter the wavelength, the more significant the C-Si bond breaking effect.

[0011] Preferably, the scanning irradiation time is 10s to 20s for each region. This is adjusted according to the type of dopant element.

[0012] Preferably, the method for introducing a dopant element source to the surface of a SiC substrate is to introduce a gaseous dopant element source.

[0013] Preferably, the flow rate of the gaseous dopant source is 20 sccm to 30 sccm, and the time is 20 to 30 minutes.

[0014] Preferably, when the dopant source is gaseous, the method for introducing the dopant source to the SiC substrate surface is to introduce the dopant source; when the dopant source is liquid or solid, the method for introducing the dopant source to the SiC substrate surface is to heat the dopant source into gaseous thermal vapor and then introduce the gaseous dopant source.

[0015] Preferably, the dopant element source is O2, N2, B2 or Al vapor.

[0016] Preferably, the doping element is selected from elements with an atomic radius of 77 pm to 138 pm.

[0017] Preferably, the doping element is O, B, N or Al.

[0018] Preferably, the SiC substrate has a cubic 3C-SiC, tetragonal 4H-SiC, or hexagonal 6H-SiC crystal form.

[0019] A second objective of this invention is to provide a SiC-based semiconductor photosensitive element, which is prepared by the above-described method.

[0020] Compared with the prior art, the present invention has the following technical effects: This invention combines high-temperature pyrolysis with pulsed laser assistance. Under high-temperature assistance, the C-Si bonds on the SiC surface are activated, and laser irradiation breaks the C-Si bonds. Simultaneously, the dopant elements adsorbed on the SiC surface are embedded in 3 to 5 atomic layers on the SiC surface in atomic form, forming a new crystal structure. This ensures the integrity of the SiC bulk crystal structure, avoids lattice distortion, suppresses defect generation, obtains high-quality SiC-based semiconductor photosensitive elements, and improves their photoresponse performance.

[0021] The SiC photosensitive element prepared by this invention has good absorption in the visible and near-infrared light regions, and also exhibits good electrical transport properties.

[0022] The high-temperature pyrolysis combined with pulsed laser-assisted technology used in this invention results in a clean and pollution-free preparation process with extremely short reaction time and higher preparation efficiency. Attached Figure Description

[0023] Figure 1 Optical photographs of the SiC-based semiconductor photosensitive elements prepared in Comparative Example 1 and Example 1. (a) is Comparative Example 1; (b) is Example 1.

[0024] Figure 2 Optical photographs of the SiC-based semiconductor photosensitive elements prepared in Comparative Example 2 and Example 1 are shown. (a) is Comparative Example 2; (b) is Example 1.

[0025] Figure 3 X-ray diffraction patterns of SiC and the SiC-based semiconductor photosensitive element prepared in Example 1.

[0026] Figure 4 X-ray diffraction patterns of SiC and the SiC-based semiconductor photosensitive element prepared in Example 2.

[0027] Figure 5 X-ray diffraction patterns of SiC and the SiC-based semiconductor photosensitive element prepared in Example 3.

[0028] Figure 6 The absorption spectra of the SiC-based semiconductor photosensitive elements prepared in Comparative Example 1 and Example 1 are shown.

[0029] Figure 7 Absorption spectra of SiC and SiC-based semiconductor photosensitive elements prepared in Example 2.

[0030] Figure 8 Absorption spectra of SiC and the SiC-based semiconductor photosensitive element prepared in Example 3. Detailed Implementation

[0031] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0032] Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0033] Example 1 A method for fabricating a SiC-based semiconductor photosensitive element includes the following steps: A 5cm×5cm 3C-SiC single crystal wafer was immersed in diluted hydrofluoric acid for 30 minutes, then cleaned with cyclohexane to remove surface oxides, rinsed with deionized water, and dried with nitrogen.

[0034] The cleaned 3C-SiC single crystal wafer was placed in a quartz tube furnace, argon gas was introduced as a protective gas, the temperature was raised to 500℃, and the temperature was kept constant for 2 hours to thermally activate the 3C-SiC single crystal wafer.

[0035] Maintain the furnace temperature at 500℃, switch the atmosphere to high-purity O2 at a flow rate of 20 sccm, and continuously introduce it for 20 minutes to perform surface oxygen doping.

[0036] Under continuous O2 and 500℃ heating conditions, a fast laser with a wavelength of 1064nm, a power of 1W, and a pulse of 500Hz is used to scan and irradiate the surface of a 3C-SiC single crystal wafer. Each area is irradiated for 10 seconds until all crystal surface areas are irradiated. The spot diameter is 2 mm, thus obtaining a SiC-based semiconductor photosensitive element.

[0037] Example 2 A method for fabricating a SiC-based semiconductor photosensitive element includes the following steps: The difference from Example 1 is that: 6H-SiC single crystal wafers are used; the heating temperature is 600℃; and the laser power is 3W.

[0038] A 5cm×5cm 6H-SiC single crystal wafer was immersed in diluted hydrofluoric acid for 30 minutes, then cleaned with cyclohexane to remove surface oxides, rinsed with deionized water, and dried with nitrogen.

[0039] The cleaned 6H-SiC wafers were placed in a quartz tube furnace, argon gas was introduced as a protective gas, the temperature was raised to 600℃, and the temperature was kept constant for 2 hours to thermally activate the 6H-SiC single crystal wafers.

[0040] Maintain the furnace temperature at 600℃, switch the atmosphere to high-purity O2 at a flow rate of 30 sccm, and continuously introduce it for 30 minutes to perform surface oxygen doping.

[0041] Under continuous O2 and 600℃ heating conditions, a fast laser with a wavelength of 1064nm, a power of 3W, and a pulse of 500Hz is used to scan and irradiate the surface of a 6H-SiC single crystal wafer until all crystal planes are irradiated. The spot diameter is 2 mm, thus obtaining a SiC-based semiconductor photosensitive element.

[0042] Example 3 A method for fabricating a SiC-based semiconductor photosensitive element includes the following steps: The difference from Example 1 is that: 4H-SiC single crystal wafers are used; the doping element source is Al vapor; the heating temperature is 700℃; the laser wavelength is 532nm and the power is 5W.

[0043] A 5cm×5cm 4H-SiC single crystal wafer was immersed in diluted hydrofluoric acid for 30 minutes, then cleaned with cyclohexane to remove surface oxides, rinsed with deionized water, and dried with nitrogen.

[0044] The cleaned 4H-SiC wafers were placed in a quartz tube furnace, argon gas was introduced as a protective gas, the temperature was raised to 700℃, and the temperature was kept constant for 2 hours to thermally activate the 6H-SiC single crystal wafers.

[0045] Maintain the furnace temperature at 700℃, switch the atmosphere to Al vapor at a flow rate of 20 sccm, and continuously introduce it for 20 minutes to perform surface Al element doping.

[0046] Under continuous Al vapor and heating at 700℃, a fast laser with a wavelength of 532nm, a power of 5W, and a pulse of 500Hz is used to scan and irradiate the surface of a 4H-SiC single crystal wafer until all crystal planes are irradiated. The spot diameter is 2 mm, thus obtaining a SiC-based semiconductor photosensitive element.

[0047] Comparative Example 1 A method for fabricating a SiC-based semiconductor photosensitive element includes the following steps: The difference from Example 1 is that only laser irradiation treatment is used.

[0048] A 3C-SiC single crystal wafer with a size of 5m×5cm was selected and immersed in diluted hydrofluoric acid for 30 minutes, then cleaned with cyclohexane to remove surface oxides, rinsed with deionized water, and dried with nitrogen.

[0049] The cleaned 3C-SiC single crystal wafer was placed in a quartz tube furnace, and high-purity O2 was introduced at a flow rate of 20 sccm for 20 minutes to perform surface oxygen doping.

[0050] Under continuous O2 conditions, a fast laser with a wavelength of 1064nm, a power of 1W, and a pulse of 500Hz is used to scan and irradiate the surface of a 3C-SiC single crystal wafer until all crystal planes are irradiated. The spot diameter is 2 mm, thus obtaining a SiC-based semiconductor photosensitive element.

[0051] Comparative Example 2 A method for fabricating a SiC-based semiconductor photosensitive element includes the following steps: The difference from Example 1 is that only heat treatment is used.

[0052] A 3C-SiC single crystal wafer with a size of 5m×5cm was selected and immersed in diluted hydrofluoric acid for 30 minutes, then cleaned with cyclohexane to remove surface oxides, rinsed with deionized water, and dried with nitrogen.

[0053] The cleaned 3C-SiC single crystal wafer was placed in a quartz tube furnace, argon gas was introduced as a protective gas, the temperature was raised to 500℃, and the temperature was kept constant for 2 hours to thermally activate the 3C-SiC single crystal wafer.

[0054] Maintain the furnace temperature at 500℃, switch the atmosphere to high-purity O2 at a flow rate of 20 sccm, and continuously introduce it for 20 minutes to perform surface oxygen doping.

[0055] like Figure 1 As shown, compared to the optical transmittance of the SiC-based semiconductor photosensitive element prepared using only a single laser treatment in Comparative Example 1, the optical transmittance of the SiC-based semiconductor photosensitive element significantly decreased after the combined high-temperature pyrolysis and pulsed laser-assisted treatment in Example 1. This indicates that the SiC-based semiconductor photosensitive element prepared in the embodiments of the present invention has good absorption of visible light.

[0056] like Figure 2 As shown, compared to the SiC-based semiconductor photosensitive element prepared by heat treatment only in Comparative Example 2, the optical transmittance of the SiC-based semiconductor photosensitive element after the high-temperature pyrolysis combined with pulsed laser-assisted treatment in Example 1 is significantly reduced. This indicates that the SiC-based semiconductor photosensitive element prepared in the embodiments of the present invention has good absorption of visible light.

[0057] like Figures 3-5 As shown, the crystal structure of the SiC-based semiconductor photosensitive elements prepared in Examples 1 to 3 remained unchanged, indicating that the bulk structure of SiC was intact. This demonstrates that the embodiments of the present invention combine high-temperature pyrolysis with pulsed laser assistance. Under high-temperature assistance, the C-Si bonds on the SiC surface are activated, and laser irradiation causes the C-Si bonds to break. Simultaneously, the dopant elements adsorbed on the SiC surface are embedded in 3 to 5 atomic layers on the SiC surface in atomic form, ensuring the integrity of the SiC bulk crystal structure.

[0058] like Figure 6 As shown, compared with the SiC-based semiconductor photosensitive element of Comparative Example 1, the SiC-based semiconductor photosensitive element prepared in Example 1 has good absorption in the visible light region and near-infrared light region of 400 nm to 700 nm.

[0059] like Figures 7-8 As shown, compared to SiC single crystal wafers, the SiC-based semiconductor photosensitive elements prepared in Examples 2 and 3 exhibit good absorption in the visible and near-infrared regions of 400 nm to 700 nm.

[0060] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0061] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for fabricating a SiC-based semiconductor photosensitive element, characterized in that, Includes the following steps: Under a protective atmosphere, the SiC substrate is heated to 300℃~900℃ for thermal activation; Under heating conditions, a dopant source is introduced into the surface of a SiC substrate, and the surface of the SiC substrate is scanned and irradiated with a laser to induce the dopant element to embed into 3 to 5 atomic layers on the surface of the SiC substrate, thereby obtaining a SiC semiconductor photosensitive element.

2. The method for fabricating a SiC-based semiconductor photosensitive element according to claim 1, characterized in that, The heating temperature is 500℃~700℃.

3. The method for fabricating a SiC-based semiconductor photosensitive element according to claim 1, characterized in that, The conditions for scanning and irradiating the surface of a SiC substrate with a laser are: laser wavelength of 532nm to 1064nm and pulse power of 1W to 5W.

4. The method for fabricating a SiC-based semiconductor photosensitive element according to claim 1, characterized in that, The method for introducing a dopant element source to the surface of a SiC substrate is to introduce a gaseous dopant element source.

5. The method for fabricating a SiC-based semiconductor photosensitive element according to claim 4, characterized in that, The flow rate of the gaseous dopant source is 20 sccm to 30 sccm, and the time is 20 to 30 minutes.

6. The method for fabricating a SiC-based semiconductor photosensitive element according to claim 1, characterized in that, The doping elements are selected from elements with atomic radii of 77 pm to 138 pm.

7. The method for fabricating a SiC-based semiconductor photosensitive element according to claim 1, characterized in that, The doping element is O, B, N or Al.

8. A SiC-based semiconductor photosensitive element, characterized in that, The SiC-based semiconductor photosensitive element is prepared by the method for preparing the SiC-based semiconductor photosensitive element according to any one of claims 1 to 7.

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