Photoelectric detector based on pva regulating sno conductivity type and preparation method and application thereof

Abstract

The application discloses a kind of photoelectric detector based on PVA regulation SnO conductivity type and preparation method, application thereof.The detector includes silicon substrate, polyvinyl alcohol interface regulation layer, N-type stannous oxide channel layer and electrode layer which are stacked in sequence.The preparation method is: spin-coating PVA film on silicon substrate and drying, depositing stannous oxide film by magnetron sputtering, annealing at 520-680 DEG C in air atmosphere, and finally preparing electrode.The application utilizes the synergistic effect of PVA thermal decomposition and high-temperature annealing to stabilize the conversion of SnO from intrinsic P-type to high-performance N-type.The obtained detector has high on-off ratio, high mobility, fast light response and low dark current, and the process is simple, low in cost, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, specifically relating to a photodetector based on PVA-controlled SnO conductivity, its preparation method, and its application. Background Technology

[0002] As a typical wide-bandgap p-type oxide semiconductor, tin suboxide (SnO) has significant application potential in fields such as solar-blind ultraviolet detection. However, its intrinsic and stable p-type conductivity severely limits the performance ceiling and functional expansion of SnO-based channel layer photodetectors. On the one hand, this hinders the construction of SnO-based complementary CMOS optoelectronic integrated circuits; on the other hand, it also poses a fundamental challenge to developing high-performance unipolar N-type SnO photodetectors with high on / off ratios, high mobility, and fast response characteristics.

[0003] To achieve conductivity type conversion in SnO, existing technologies typically employ complex heterostructures or doping with foreign elements. However, these methods often suffer from poor process compatibility, difficulty in controlling doping uniformity, numerous interface defects, or insufficient thermal stability, resulting in poor quality of the prepared N-type tin oxide thin films. Ultimately, this makes it difficult for key performance indicators of the detector, such as dark current, response speed, and stability, to meet the requirements of practical applications.

[0004] Therefore, developing a new method that is simple, low-cost, and can stably obtain high-quality N-type tin oxide thin films, and then constructing high-performance photodetectors based on this method, has become an urgent technological need to drive the development of this field. Summary of the Invention

[0005] Aiming to address the technical problem of the urgent need for a photodetector with an N-type tin oxide thin film that is simple to fabricate, low in cost, and has excellent performance, this invention provides a photodetector based on PVA-modulated SnO conductivity, comprising: A silicon substrate, a polyvinyl alcohol interface control layer, an N-type tin oxide channel layer, and an electrode layer are sequentially stacked. The silicon substrate includes a monocrystalline silicon layer and a silicon oxide insulating layer; The polyvinyl alcohol interface control layer is attached to the surface of the silicon oxide insulating layer; The N-type stannous oxide channel layer is a crystalline thin film that has been annealed at a high temperature of 520°C-680°C in air and covers the polyvinyl alcohol interface control layer. The electrode layer includes a source electrode and a drain electrode, which are disposed at intervals on the surface of the N-type tin oxide channel layer and form an ohmic contact with the N-type tin oxide channel layer.

[0006] Furthermore, the on / off ratio of the photodetector is not less than 3.0 × 10⁻⁶. 3 The migration rate is not less than 20 cm. 2 / V·s, dark current not greater than 1.0×10 -8 A; At a wavelength of 365nm and a light intensity of 1 W / cm² 2 Under ultraviolet light irradiation, the photoresponse rise time is no more than 0.5s and the fall time is no more than 1.0s.

[0007] This invention provides a method for fabricating a photodetector based on PVA-modulated SnO conductivity, comprising the following steps: A silicon substrate is provided, and a polyvinyl alcohol interface control layer is formed on the surface of the silicon oxide insulating layer of the silicon substrate; A tin oxide film is deposited on the surface of the polyvinyl alcohol interface control layer, followed by high-temperature annealing at 520℃-680℃ for 10-30 minutes to form an N-type tin oxide channel layer. A source electrode and a drain electrode are fabricated at intervals on the surface of the N-type tin oxide channel layer, and the source electrode and the drain electrode form an ohmic contact with the N-type tin oxide channel layer to obtain the photodetector.

[0008] Furthermore, the silicon substrate includes a monocrystalline silicon layer and a silicon oxide insulating layer, wherein the monocrystalline silicon layer is composed of p-doped silicon.

[0009] Furthermore, the step of forming a polyvinyl alcohol interface control layer on the surface of the silicon oxide insulating layer on the silicon substrate includes: forming a polyvinyl alcohol film on the surface of the silicon oxide insulating layer by spin coating, followed by baking at 30-60°C for 12-14 hours.

[0010] Furthermore, the deposition of a tin oxide film on the surface of the polyvinyl alcohol interface control layer includes: depositing a tin oxide film on the surface of the polyvinyl alcohol interface control layer by magnetron sputtering.

[0011] Furthermore, the deposition of tin suboxide thin film by magnetron sputtering specifically includes: The back vacuum is no higher than 5×10. -4 Under the conditions of Pa, pure tin target is used as target material, and a mixture of argon and oxygen gas is introduced. Sputtering deposition is carried out under the conditions of total pressure of 0.3-0.7 Pa and radio frequency power of 25-35W.

[0012] Furthermore, the process of fabricating source and drain electrodes spaced apart on the surface of the N-type tin oxide channel layer includes: Source and drain electrodes are deposited on the surface of the tin oxide thin film using an electron beam evaporation deposition system.

[0013] Furthermore, the electron beam evaporation deposition system includes an electron beam system and a thermal evaporation system; a chromium layer is deposited on the surface of the N-type tin oxide channel layer by the electron beam system, and a gold layer is deposited on the surface of the chromium layer by the thermal evaporation system to form the source electrode and the drain electrode; The thickness of the chromium layer is 15nm-25nm; and / or the thickness of the gold layer is 45nm-55nm.

[0014] This invention provides an application of a photodetector prepared by the method described above for preparing a photodetector based on PVA-controlled SnO conductivity, or prepared by the method described above for preparing a photodetector based on PVA-controlled SnO conductivity in ultraviolet light detection, ultraviolet light communication, and ultraviolet imaging.

[0015] Compared with the prior art, the present invention has at least the following advantages: This invention provides a photodetector based on PVA-controlled SnO conductivity type. Unlike traditional ion doping or complex heterojunction engineering, it creatively utilizes reducing small molecules (such as hydrogen-containing free radicals) released during the thermal decomposition of polyvinyl alcohol (PVA) during high-temperature annealing to precisely and selectively control oxygen vacancy defects in stannous oxide thin films in situ. This mechanism not only achieves a stable upward shift of the SnO Fermi level, thereby efficiently and stably converting its conductivity type from intrinsic P-type to N-type, but more importantly, it avoids scattering centers introduced by foreign impurities, laying the physical foundation for obtaining high-mobility channel layers.

[0016] The N-type stannous oxide channel layer and its photodetector, prepared based on the above mechanism, achieved the following performance optimizations: Ultra-high on / off ratio and high mobility: This is directly attributed to the low defect density N-type channel generated by PVA modulation and the excellent channel / dielectric layer interface, which significantly optimizes the gate voltage modulation capability and carrier transport efficiency.

[0017] Fast photoelectric response and extremely low dark current: This demonstrates that the channel layer has excellent photogenerated carrier generation, separation and collection efficiency, as well as extremely low defect-state assisted recombination, meeting the core requirements of high-performance photodetectors.

[0018] This invention also provides a method for fabricating a photodetector based on PVA-controlled SnO conductivity type. This method integrates complex conductivity type conversion and performance optimization into a simple, standard process, eliminating complex processes such as multi-step doping and epitaxial capping. The N-type conversion and interface passivation can be simultaneously achieved through a concise process of spin-coating PVA + standard sputtering + single-step annealing. PVA is inexpensive, readily available, and highly water-soluble. The entire process is highly compatible with mainstream semiconductor manufacturing platforms, significantly improving performance while greatly reducing fabrication complexity and manufacturing costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a photodetector fabricated in one embodiment of the present invention. 1. Single-crystal silicon layer; 2. Silicon oxide insulating layer; 3. Polyvinyl alcohol interface control layer; 4. N-type tin oxide channel layer; 5. Source electrode; 6. Drain electrode; Figure 2 The transfer curves of the photodetectors of Embodiment 1 and Comparative Example 1 of the present invention at gate voltages from -30V to 30V are shown. Figure 3 The output curve of the photodetector gate voltage from 0-50V in Embodiment 1 of the present invention is shown. Figure 4 The image shows the response time of the photocurrent rising and falling edges of the photodetector in Embodiment 1 of the present invention under the conditions of incident light with a wavelength of 380 nm and a source-drain voltage of 5 V. Figure 5 The transfer characteristic curves of the photodetector of Embodiment 1 of the present invention under three different optical power densities under the conditions of incident light with a wavelength of 380nm and source-drain voltage of 5V. Figure 6 The photoresponse time diagrams of the photodetector of Embodiment 1 of the present invention under three different optical power densities under the conditions of incident light with a wavelength of 380nm and a source-drain voltage of 5V. Figure 7 The curves show the variation of electron mobility in Example 1 and hole mobility in Comparative Example 1 from 10V to 30V. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When 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 the present invention.

[0023] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of the invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention.

[0024] like Figure 1 As shown, this invention provides a photodetector based on PVA-controlled SnO conductivity, comprising: A silicon substrate, a polyvinyl alcohol interface control layer, an N-type tin oxide channel layer, and a source electrode and a drain electrode are sequentially stacked. The silicon substrate includes a monocrystalline silicon layer and a silicon oxide insulating layer thereon; The polyvinyl alcohol interface control layer is attached to the surface of the silicon oxide insulating layer; The N-type stannous oxide channel layer is a crystalline thin film that has been annealed at a high temperature of 520°C to 680°C in air atmosphere, and covers the polyvinyl alcohol interface control layer. The source electrode and drain electrode are spaced apart on the surface of the N-type tin oxide channel layer and form an ohmic contact with the N-type tin oxide channel layer.

[0025] In some embodiments, the duration of the high-temperature annealing treatment can be 10-30 min; in some more specific embodiments, the duration of the high-temperature annealing treatment can be 15-30 min, 10-15 min, 10-20 min, or 10-25 min.

[0026] In some embodiments, the high-temperature annealing temperature can be 520-600℃, 550-650℃, 600-650℃, 500-620℃, 550-600℃, 550-620℃, or 550-680℃.

[0027] In this invention, the on / off ratio of the photodetector is not less than 3.0 × 10⁻⁶. 3 The migration rate is not less than 20 cm. 2 / V·s, dark current not greater than 1.0×10 -8 A; at a wavelength of 365nm and a light intensity of 1 W / cm² 2Under ultraviolet light irradiation, the photoresponse rise time is no more than 0.5s and the fall time is no more than 1.0s.

[0028] In some embodiments, the on / off ratio of the photodetector may be not less than 3.5 × 10⁻⁶. 3 It can also be 3.5 × 10 3 -8.0×10 3 For example, the on / off ratio of the photodetector may be no less than 4.0 × 10⁻⁶. 3 It can also be 4.0×10 3 -8.0×10 3 Furthermore, by way of example, the on / off ratio of the photodetector may be no less than 5.0 × 10⁻⁶. 3 It can also be 5.0×10 3 -8.0×10 3 Furthermore, by way of example, the on / off ratio of the photodetector may be no less than 6.0 × 10⁻⁶. 3 It can also be 6.0×10 3 -8.0×10 3 .

[0029] In some embodiments, the mobility of the photodetector may be not less than 30 cm. 2 / V·s, or 30-300 cm 2 / V·s or 30-250 cm 2 / V·s or 30-200 cm 2 / V·s; For example, the mobility of the photodetector can be no less than 50 cm. 2 / V·s, or 50-300 cm 2 / V·s or 50-250 cm 2 / V·s or 50-200cm 2 / V·s; and, by way of example, the mobility of the photodetector may be not less than 100 cm⁻¹. 2 / V·s, or 100-300 cm 2 / V·s or 100-250 cm 2 / V·s or 100-200 cm 2 / V·s; and, by way of example, the mobility of the photodetector may be not less than 150 cm⁻¹. 2 / V·s, or 150-300 cm 2 / V·s or 150-250 cm 2 / V·s or 150-200cm 2 / V·s.

[0030] In some embodiments, the dark current of the photodetector may not exceed 5 × 10⁻⁶. -9 A can also be 5×10 -10 A-5×10 -9 A or 1×10 -9 A-5×10 -9 A; For example, the dark current of the photodetector may not exceed 4 × 10⁻⁶. - 9 A can also be 5×10 -10 A-4×10 -9 A or 1×10 -9 A-4×10 -9 A; and, by way of example, the dark current of the photodetector may not exceed 3 × 10⁻⁶. -9 A can also be 5×10 -10 A-3×10 -9 A or 1×10 -9 A-3×10 -9 A.

[0031] In some embodiments, at a wavelength of 365 nm and a light intensity of 1 W / cm², 2 Under ultraviolet light irradiation, the rise time of the photoresponse can be no more than 0.3s and the fall time can be no more than 0.8s.

[0032] This invention also provides a method for fabricating a photodetector based on PVA-modulated SnO conductivity, comprising the following steps: S1. A silicon substrate is provided, and a polyvinyl alcohol interface control layer is formed on the surface of the silicon oxide insulating layer of the silicon substrate.

[0033] In this invention, the silicon substrate comprises a lower layer of monocrystalline silicon and an upper layer of silicon oxide, wherein the monocrystalline silicon is p-doped silicon.

[0034] In some embodiments, the preparation of the silicon substrate includes the steps of: providing a silicon wafer, cleaning and drying it to obtain a clean silicon substrate.

[0035] For example, the cleaning process includes ultrasonic cleaning of the silicon wafer in sequence using acetone, isopropanol and deionized water; the drying process is gradient temperature drying.

[0036] The purpose of the cleaning and drying processes is to remove impurities and natural oxide layers from the silicon wafer surface to ensure cleanliness, strengthen the interfacial adhesion between the PVA film and the silicon substrate, eliminate surface state differences between different batches of silicon wafers, and provide a stable substrate for subsequent thin film deposition and device fabrication.

[0037] In some more specific embodiments, the ultrasonic cleaning is performed at a power of 500W, and the cleaning time in acetone, isopropanol and deionized water is 10 minutes each; the gradient temperature drying is performed in four temperature stages: 35-45℃, 50-60℃, 75-85℃ and 105-115℃, with a holding time of 8-12 minutes for each temperature stage.

[0038] For example, the gradient heating drying is carried out in four temperature stages: 40°C, 55°C, 80°C and 110°C, with a holding time of 8-12 minutes for each temperature stage.

[0039] It should be noted that gradient heating can prevent sudden temperature changes from causing microcracks in the silicon oxide layer of the silicon wafer or delamination at the interface of the silicon wafer. At the same time, since acetone, isopropanol and deionized water have different boiling points, we also choose gradient heating to avoid leaving watermarks or other unevenness on the surface of the silicon wafer during the drying process.

[0040] It should be noted that the silicon substrate can be, for example, a single-layer polished silicon oxide wafer (P-type) provided by Suzhou Crystal Silicon Electronics Technology Co., Ltd., as the starting material. This commercially available silicon wafer can be directly purchased.

[0041] In this invention, forming a polyvinyl alcohol interface control layer on the surface of the silicon oxide insulating layer on the silicon substrate includes: forming a polyvinyl alcohol film on the surface of the silicon oxide insulating layer by spin coating, followed by baking at 30-60°C for 12-14 hours.

[0042] In some embodiments, the spin coating may include pre-spin coating and main spin coating; wherein, the pre-spin coating speed may be 700-900 / rps, and the time may be 5-20s; the main spin coating speed may be 1500-2500 / rps, and the time may be 50-70s. After spin coating is completed, it can be placed in a baking machine at 40-50℃ for 12-14 hours and then set aside for later use.

[0043] In this invention, the thickness of the polyvinyl alcohol interface control layer, i.e., the PVA film, can be 20-25 nm.

[0044] S2. A tin oxide film is deposited on the surface of the polyvinyl alcohol interface control layer, and then subjected to high-temperature annealing at 520℃-680℃ for 10-30 minutes to form an N-type tin oxide channel layer.

[0045] In this invention, the deposition of a tin oxide film on the surface of the polyvinyl alcohol interface control layer includes: depositing a tin oxide film on the surface of the polyvinyl alcohol interface control layer by magnetron sputtering.

[0046] In some embodiments, the deposition of a tin oxide thin film by magnetron sputtering may specifically include: The back vacuum is no higher than 5×10. -4 Under conditions of 0.3-0.7 Pa, using a pure tin target as the target material, a mixture of argon and oxygen (the volume ratio of argon to oxygen can be 40-50:1) is introduced, and sputtering deposition is performed under conditions of a total pressure of 0.3-0.7 Pa and an RF power of 25-35 W. The sputtering time can be 50-70 s. For example, a pre-sputtering of about 550-650 s can be performed before introducing the mixed gas.

[0047] After sputtering, the sample can be transferred to a tube furnace and heated in air at 15-50°C for [time range missing]. -1 The temperature is increased to the high-temperature annealing temperature at a certain rate for high-temperature annealing, followed by natural cooling to room temperature to form the N-type tin oxide channel layer. For example, the heating rate can also be 20-50℃ / min. -1 Or 20-35℃ min -1 or 20-40℃min -1 .

[0048] In some embodiments, a tin oxide film can be deposited on the surface of a PVA film using a DM400 three-target magnetron sputtering instrument.

[0049] In this invention, the thickness of the N-type tin oxide channel layer can be 15-20 nm.

[0050] In some embodiments, the deposition rate can be 0.01-0.02 nm / s.

[0051] S3. A source electrode and a drain electrode spaced apart from each other are formed on the surface of the N-type tin oxide channel layer, and the source electrode and the drain electrode form an ohmic contact with the N-type tin oxide channel layer, thereby obtaining the photodetector.

[0052] In this invention, the fabrication of mutually spaced source and drain electrodes on the surface of the N-type tin oxide channel layer includes: Source and drain electrodes are deposited on the surface of the tin oxide thin film using an electron beam evaporation deposition system.

[0053] In some embodiments, the electron beam evaporation deposition system includes an electron beam system and a thermal evaporation system; a chromium layer is deposited on the surface of the N-type tin oxide channel layer by the electron beam system, and a gold layer is deposited on the surface of the chromium layer by the thermal evaporation system to form the source electrode and the drain electrode; The thickness of the chromium layer is 15nm-25nm; and / or the thickness of the gold layer is 45nm-55nm.

[0054] In some embodiments, the source electrode and the drain electrode are both chromium / gold bilayer electrodes, consisting of two layers of material, including a lower layer of Cr and an upper layer of Au.

[0055] In some embodiments, the deposition rate can be 0.01-0.02 nm / s.

[0056] The technical effects of this invention are as follows: By introducing a polyvinyl alcohol (PVA) interface control layer and combining it with a specific high-temperature annealing process, the resulting technical effect is not a simple improvement of a single factor, but rather a synergistic effect of the chemical control effect of PVA and the thermodynamic effect of high-temperature annealing. This achieves systematic optimization of the SnO channel layer, ultimately leading to the optimization of the overall performance of the photodetector. Specifically, this is manifested as follows: First, PVA undergoes thermal decomposition during high-temperature annealing, releasing reducing small molecules (such as hydrogen-containing species). These molecules, along with the activation energy provided by the high temperature, enable in-situ, selective chemical modification of intrinsic defects (mainly oxygen vacancies) within the tin oxide film.

[0057] This synergistic process precisely modulates the oxygen vacancy concentration and energy level, stably pinning the Fermi level near the conduction band bottom, thereby stably and efficiently transforming SnO from an intrinsic P-type semiconductor. Simultaneously, this process significantly reduces the deep-level defect density within the thin film.

[0058] Stable N-type conductivity is a prerequisite for constructing high-performance n-channel devices. Low defect density significantly reduces defect-assisted thermal excitation and recombination of carriers, thereby significantly reducing the dark current of the device in the dark state. At the same time, the reduction in defect density effectively reduces scattering and recombination during carrier transport, resulting in an order-of-magnitude increase in carrier mobility and significantly accelerating the separation and collection efficiency of photogenerated carriers, thus shortening the photoresponse time.

[0059] Secondly, the PVA layer, acting as an interface buffer layer between the SiO2 insulating layer and the SnO channel layer, plays a role both before and after annealing. Its decomposition products can effectively passivate the dangling bonds on the SiO2 surface. This significantly reduces the interface state density between the gate dielectric and the channel layer, forming a heterogeneous interface with superior electrical performance.

[0060] The low interface state density allows the gate voltage to more effectively regulate the carrier concentration within the channel without being shielded or hysteresised by interface traps. This directly translates into an extremely high switching current ratio, i.e., superior switching characteristics.

[0061] In summary, the synergy between the PVA interface layer and the high-temperature annealing process is not a simple summation of their individual effects, but rather a linkage mechanism of chemical defect reduction and interface electronic passivation. This enables the photodetector to simultaneously possess multiple outstanding performance indicators such as high mobility, extremely low dark current, ultra-high on / off ratio, and fast photoresponse, thus solving the technical bottleneck of balancing excellent performance, low cost, and process simplicity in the fabrication of high-performance N-type SnO photodetectors.

[0062] The present invention also provides an application of the photodetector prepared by the photodetector based on PVA-controlled SnO conductivity type as described above or by the photodetector prepared by the photodetector based on PVA-controlled SnO conductivity type as described above in photoelectric detection and information processing in the ultraviolet band. The photoelectric detection and information processing in the ultraviolet band mainly includes ultraviolet light detection, ultraviolet light communication, and ultraviolet imaging.

[0063] To facilitate a further understanding of the present invention by those skilled in the art, the following examples are provided: Example 1 S1. Provide a silicon substrate, and form a polyvinyl alcohol interface control layer on the surface of the silicon oxide insulating layer of the silicon substrate.

[0064] Specifically: Silicon wafers (the lower p-doped silicon and the upper silicon oxide layer, purchased from Suzhou Jingxi Electronics Technology Co., Ltd.) were ultrasonically cleaned using acetone, isopropanol, and deionized water, respectively. The wafers were then ultrasonically cleaned in deionized water for 2 minutes, followed by transfer to a vacuum drying oven and gradual temperature increase for 20 minutes to obtain a clean silicon substrate. The temperature gradient involved sequentially holding the wafers at 40℃, 55℃, 80℃, and 110℃ for 10 minutes each.

[0065] PVA films were spin-coated onto a silica substrate using a KW-4A benchtop spin coater: a pre-coating was performed at 800 rpm for 10 seconds, followed by a main spin coating at 2000 rpm for 60 seconds. After spin coating, the samples were allowed to stand for 60 seconds before being transferred to an SC-H-1 baking oven and baked at 45°C for 12 hours. Before use, the samples were removed and allowed to stand at room temperature for 30 seconds to cool to ambient temperature before proceeding with subsequent operations.

[0066] S2. A tin oxide film is deposited on the surface of the polyvinyl alcohol interface control layer, followed by high-temperature annealing at 600℃ for 15 min to form an N-type tin oxide channel layer.

[0067] Specifically: The baked and cooled PVA film was placed in a DM400 three-target magnetron sputtering system, and the back-bottom vacuum was evacuated to ≤5×10⁻⁶. -4After Pa, pre-sputtering with a pure Sn target (99.99%) for 600 s was performed to remove the oxide layer on the target surface. Then, an Ar / O2 (volume ratio 46:1) mixture was introduced, maintaining a total pressure of 0.5 Pa, and sputtering was performed at an RF power of 31 W for 60 s to deposit a thin film of tin oxide on the PVA surface. After sputtering, the sample was quickly transferred to an SK-B05123K open tube furnace and incubated at 30 °C for 1 minute in air. -1 The heating rate was increased to 600℃, and the temperature was kept constant for 20 minutes before being allowed to cool naturally to room temperature.

[0068] S3. A source electrode and a drain electrode spaced apart are fabricated on the surface of an N-type tin oxide channel layer. The source electrode and the drain electrode form an ohmic contact with the N-type tin oxide channel layer, thereby obtaining a photodetector.

[0069] Specifically: A 20 nm Cr electrode was deposited in the channel region using a DM500-1 electron beam system at a vacuum level ≤5 × 10⁻⁶. -4 Pa; then, within the same vacuum cycle, the process was switched to a DM500 thermal resistance evaporation device to deposit a 50nm Au conductive layer on the Cr layer surface, ultimately obtaining a Cr / Au (20nm / 50nm) bilayer source electrode and drain electrode.

[0070] Comparative Example 1 Compared to Example 1, the other conditions in this comparative example remain unchanged, except that the polyvinyl alcohol interface control layer is no longer formed in step S1, and the annealing temperature is adjusted to the conventional low-temperature annealing temperature (250°C).

[0071] A method for fabricating a P-type SnO photodetector comprises the following steps: S1. Provides a silicon substrate.

[0072] Specifically: Silicon wafers (the lower p-doped silicon and the upper silicon oxide layer, purchased from Suzhou Jingxi Electronics Technology Co., Ltd.) were ultrasonically cleaned using acetone, isopropanol, and deionized water, respectively. The ultrasonic cleaning in deionized water lasted for 2 minutes. The wafers were then transferred to a vacuum drying oven and dried using a gradient temperature increase for 20 minutes to obtain a clean silicon substrate. The gradient temperature increase involved holding the wafer at 40℃, 55℃, 80℃, and 110℃ for 10 minutes each.

[0073] S2. A tin oxide thin film is deposited on the surface of a silicon substrate and then annealed at 250°C to obtain a P-type tin oxide channel layer.

[0074] Specifically: The silicon substrate was placed in a DM400 three-target magnetron sputtering system, and the back-bottom vacuum was evacuated to ≤5×10⁻⁶. -4After Pa, pre-sputtering was performed for 600 s with a pure Sn target (99.99%) to remove the oxide layer on the target surface. Then, an Ar / O2 (volume ratio 46:1) mixture was introduced, maintaining a total pressure of 0.5 Pa, and sputtering was performed for 60 s at an RF power of 31 W to deposit a thin film of tin oxide on the silicon substrate. After sputtering, the sample was quickly transferred to an SK-B05123K open tube furnace and sputtered at 30 °C for 1 minute in an air atmosphere. -1 The heating rate was increased to 250℃, and the temperature was kept constant for 10 minutes before naturally cooling to room temperature.

[0075] S3. A source electrode and a drain electrode spaced apart are fabricated on the surface of a P-type tin oxide channel layer. The source electrode and the drain electrode form an ohmic contact with the N-type tin oxide channel layer, thereby obtaining a photodetector.

[0076] Specifically: A 20 nm Cr electrode was deposited in the channel region using a DM500-1 electron beam deposition system, with a vacuum degree ≤5 × 10⁻⁶. - 4 Pa; then, within the same vacuum cycle, the system was switched to a DM500 thermal resistance evaporation device to deposit a 50nm Au conductive layer on the Cr layer surface, ultimately obtaining a Cr / Au (20nm / 50nm) bilayer source and drain ohmic electrode.

[0077] Performance testing and results analysis: Figure 2 The transfer curves of the photodetectors of Example 1 and Comparative Example 1 at gate voltages from -30V to 30V are shown. Figure 3 The output curve of the photodetector gate voltage from 0-50V in Example 1 is shown. Figure 4 The graph shows the response time of the photocurrent rise and fall of the photodetector in Example 1 under the conditions of incident light with a wavelength of 380 nm and a source-drain voltage of 5 V. Figure 5 The transfer characteristic curves of the photodetector of Example 1 under three different optical power densities under the conditions of incident light with a wavelength of 380 nm and a source-drain voltage of 5 V are shown. Figure 6 The photoresponse time diagrams for the photodetector of Example 1 under three different optical power densities under the conditions of incident light at a wavelength of 380 nm and source-drain voltage of 5 V are shown. Figure 7 The curves show the variation of electron mobility in Example 1 and hole mobility in Comparative Example 1 from 10V to 30V.

[0078] The performance parameters of the detectors prepared by the above method are compared (PVA-doped SnO photodetector and SnO photodetector) as shown in the table below: Table 1 Comparison of Performance Parameters As shown in Table 1, the design based on PVA-controlled SnO conductivity type in Embodiment 1 of this application significantly improves the on / off ratio, carrier mobility and photoresponse speed.

[0079] Comparative Example 2 Compared to Example 1, all other conditions in this comparative example remain unchanged, except that the temperature of the high-temperature annealing treatment is adjusted to 500°C.

[0080] S1. Provide a silicon substrate, and form a polyvinyl alcohol interface control layer on the surface of the silicon oxide insulating layer of the silicon substrate.

[0081] Specifically: Silicon wafers (the lower p-doped silicon and the upper silicon oxide layer, purchased from Suzhou Jingxi Electronics Technology Co., Ltd.) were ultrasonically cleaned using acetone, isopropanol, and deionized water, respectively. The ultrasonic cleaning in deionized water lasted for 2 minutes. The wafers were then transferred to a vacuum drying oven and dried using a gradient temperature increase for 20 minutes to obtain a clean silicon substrate. The gradient temperature increase involved holding the wafer at 40℃, 55℃, 80℃, and 110℃ for 10 minutes each.

[0082] PVA films were spin-coated onto a silica substrate using a KW-4A benchtop spin coater: a pre-coating was performed at 800 rpm for 10 seconds, followed by a main spin coating at 2000 rpm for 60 seconds. After spin coating, the samples were allowed to stand for 60 seconds before being transferred to an SC-H-1 baking oven and baked at 45°C for 12-14 hours. Before use, the samples were removed and allowed to stand at room temperature for 30 seconds to cool to ambient temperature before proceeding with subsequent operations.

[0083] S2. A tin oxide film is deposited on the surface of the polyvinyl alcohol interface control layer, followed by high-temperature annealing at 500°C for 15 min to form an N-type tin oxide channel layer.

[0084] Specifically: The baked and cooled PVA film was placed in a DM400 three-target magnetron sputtering system, and the back-bottom vacuum was evacuated to ≤5×10⁻⁶. -4After Pa, pre-sputtering was performed for 600 s with a pure Sn target (99.99%) to remove the oxide layer on the target surface. Then, an Ar / O2 (volume ratio 46:1) mixture was introduced, maintaining a total pressure of 0.5 Pa, and sputtering was performed for 60 s at an RF power of 31 W to deposit a thin film of tin oxide on the PVA surface. After sputtering, the sample was quickly transferred to an SK-B05123K open tube furnace and sputtered at 30 °C for 1 minute in an air atmosphere. -1 The heating rate was increased to 500℃, and the temperature was kept constant for 20 minutes before naturally cooling to room temperature.

[0085] S3. A source electrode and a drain electrode spaced apart are fabricated on the surface of an N-type tin oxide channel layer. The source electrode and the drain electrode form an ohmic contact with the N-type tin oxide channel layer, thereby obtaining a photodetector.

[0086] Specifically: A 20 nm Cr electrode was deposited in the channel region using a DM500-1 electron beam system at a vacuum level ≤5 × 10⁻⁶. -4 Pa; then, within the same vacuum cycle, the process was switched to a DM500 thermal resistance evaporation device to deposit a 50nm Au conductive layer on the Cr layer surface, ultimately obtaining a Cr / Au (20nm / 50nm) bilayer source electrode and drain electrode.

[0087] Test results: On / off ratio 3662, mobility 31.32 cm 2 / V·s, dark current 1.87E-8A, photoresponse time (rise / fall) 0.40s / 1.30s.

[0088] Comparative Example 3 Compared to Example 1, all other conditions remained the same in this comparative example, except that the temperature of the high-temperature annealing treatment was adjusted to 700°C.

[0089] S1. Provide a silicon substrate, and form a polyvinyl alcohol interface control layer on the surface of the silicon oxide insulating layer of the silicon substrate.

[0090] Specifically: Silicon wafers (the lower p-doped silicon and the upper silicon oxide layer, purchased from Suzhou Jingxi Electronics Technology Co., Ltd.) were ultrasonically cleaned using acetone, isopropanol, and deionized water, respectively. The ultrasonic cleaning in deionized water lasted for 2 minutes. The wafers were then transferred to a vacuum drying oven and dried using a gradient temperature increase for 20 minutes to obtain a clean silicon substrate. The gradient temperature increase involved holding the wafer at 40℃, 55℃, 80℃, and 110℃ for 10 minutes each.

[0091] PVA films were spin-coated onto a silica substrate using a KW-4A benchtop spin coater: a pre-coating was performed at 800 rpm for 10 seconds, followed by a main spin coating at 2000 rpm for 60 seconds. After spin coating, the samples were allowed to stand for 60 seconds before being transferred to an SC-H-1 baking oven and baked at 45°C for 12-14 hours. Before use, the samples were removed and allowed to stand at room temperature for 30 seconds to cool to ambient temperature before proceeding with subsequent operations.

[0092] S2. A tin oxide film is deposited on the surface of the polyvinyl alcohol interface control layer, followed by high-temperature annealing at 700℃ for 15 min to form an N-type tin oxide channel layer.

[0093] Specifically: The baked and cooled PVA film was placed in a DM400 three-target magnetron sputtering system, and the back-bottom vacuum was evacuated to ≤5×10⁻⁶. -4 After Pa, pre-sputtering with a pure Sn target (99.99%) for 600 s was performed to remove the oxide layer on the target surface. Then, an Ar / O2 (volume ratio 46:1) mixture was introduced, maintaining a total pressure of 0.5 Pa, and sputtering was performed at an RF power of 31 W for 60 s to deposit a thin film of tin oxide on the PVA surface. After sputtering, the sample was quickly transferred to an SK-B05123K open tube furnace and incubated at 30 °C for 1 minute in air. -1 The heating rate was increased to 700℃, and the temperature was kept constant for 20 minutes before being allowed to cool naturally to room temperature.

[0094] S3. A source electrode and a drain electrode spaced apart are fabricated on the surface of an N-type tin oxide channel layer. The source electrode and the drain electrode form an ohmic contact with the N-type tin oxide channel layer, thereby obtaining a photodetector.

[0095] Specifically: A 20 nm Cr electrode was deposited in the channel region using a DM500-1 electron beam system at a vacuum level ≤5 × 10⁻⁶. -4 Pa; then, within the same vacuum cycle, the process was switched to a DM500 thermal resistance evaporation device to deposit a 50nm Au conductive layer on the Cr layer surface, ultimately obtaining a Cr / Au (20nm / 50nm) bilayer source electrode and drain electrode.

[0096] Test results: On / off ratio 1359, mobility 77.14 cm 2 / V·s, dark current 3.28E-8A, photoresponse time (rise / fall) 0.19s / 1.08s.

[0097] Comparative Example 4 Compared to Example 1, the other conditions remain unchanged in this comparative example, except that the polyvinyl alcohol interface control layer is no longer formed in step S1.

[0098] S1. Provides a silicon substrate.

[0099] Specifically: Silicon wafers (the lower p-doped silicon and the upper silicon oxide layer, purchased from Suzhou Jingxi Electronics Technology Co., Ltd.) were ultrasonically cleaned using acetone, isopropanol, and deionized water, respectively. The ultrasonic cleaning in deionized water lasted for 2 minutes. The wafers were then transferred to a vacuum drying oven and dried using a gradient temperature increase for 20 minutes to obtain a clean silicon substrate. The gradient temperature increase involved holding the wafer at 40℃, 55℃, 80℃, and 110℃ for 10 minutes each.

[0100] S2. A tin suboxide thin film is deposited on the surface of a silicon substrate and then annealed at 600°C to obtain a P-type tin suboxide channel layer.

[0101] Specifically: The silicon substrate was placed in a DM400 three-target magnetron sputtering system, and the back-bottom vacuum was evacuated to ≤5×10⁻⁶. -4 After Pa, pre-sputtering was performed for 600 s with a pure Sn target (99.99%) to remove the oxide layer on the target surface. Then, an Ar / O2 (volume ratio 46:1) mixture was introduced, maintaining a total pressure of 0.5 Pa, and sputtering was performed for 60 s at an RF power of 31 W to deposit a thin film of tin oxide on the silicon substrate. After sputtering, the sample was quickly transferred to an SK-B05123K open tube furnace and sputtered at 30 °C for 1 minute in an air atmosphere. -1 The heating rate was increased to 600℃, and the temperature was kept constant for 10 minutes before being allowed to cool naturally to room temperature.

[0102] S3. A source electrode and a drain electrode spaced apart are fabricated on the surface of a P-type tin oxide channel layer. The source electrode and the drain electrode form an ohmic contact with the tin oxide channel layer, thereby obtaining a photodetector.

[0103] Specifically: A 20 nm Cr electrode was deposited in the channel region using a DM500-1 electron beam deposition system, with a vacuum degree ≤5 × 10⁻⁶. - 4 Pa; then, within the same vacuum cycle, the system was switched to a DM500 thermal resistance evaporation device to deposit a 50nm Au conductive layer on the Cr layer surface, ultimately obtaining a Cr / Au (20nm / 50nm) bilayer source and drain ohmic electrode.

[0104] Test results: SnO has been oxidized into Sn and SnO2, and no longer possesses the properties of a semiconductor; it is a conductor.

[0105] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for fabricating a photodetector based on PVA-controlled SnO conductivity, characterized in that, Including the following steps: A silicon substrate is provided, and a polyvinyl alcohol interface control layer is formed on the surface of the silicon oxide insulating layer of the silicon substrate; A tin oxide film is deposited on the surface of the polyvinyl alcohol interface control layer, and then subjected to high-temperature annealing at 520-680℃ for 10-30 min to form an N-type tin oxide channel layer. A source electrode and a drain electrode are fabricated at intervals on the surface of the N-type tin oxide channel layer, and the source electrode and the drain electrode form an ohmic contact with the N-type tin oxide channel layer to obtain the photodetector.

2. The method for fabricating a photodetector based on PVA-controlled SnO conductivity as described in claim 1, characterized in that, The silicon substrate includes a monocrystalline silicon layer and a silicon oxide insulating layer, wherein the monocrystalline silicon layer is composed of p-doped silicon.

3. The method for fabricating a photodetector based on PVA-controlled SnO conductivity as described in claim 1, characterized in that, The formation of a polyvinyl alcohol interface control layer on the surface of the silicon oxide insulating layer on the silicon substrate includes: forming a polyvinyl alcohol film on the surface of the silicon oxide insulating layer by spin coating, followed by baking; the baking temperature is 30-60℃, and the baking time is 12-14h.

4. The method for fabricating a photodetector based on PVA-controlled SnO conductivity as described in claim 1, characterized in that, The deposition of a tin oxide film on the surface of the polyvinyl alcohol interface control layer includes: depositing a tin oxide film on the surface of the polyvinyl alcohol interface control layer by magnetron sputtering.

5. The method for fabricating a photodetector based on PVA-controlled SnO conductivity as described in claim 4, characterized in that, The deposition of tin oxide thin film by magnetron sputtering includes: The back vacuum is no higher than 5×10. -4 Under the conditions of Pa, pure tin target is used as target material, and a mixture of argon and oxygen gas is introduced. Sputtering deposition is carried out under the conditions of total pressure of 0.3-0.7 Pa and radio frequency power of 25-35W.

6. The method for fabricating a photodetector based on PVA-controlled SnO conductivity as described in claim 1, characterized in that, The source and drain electrodes spaced apart on the surface of the N-type tin oxide channel layer include: The source electrode and the drain electrode are deposited on the surface of the tin oxide thin film using an electron beam evaporation deposition system.

7. The method for fabricating a photodetector based on PVA-controlled SnO conductivity as described in claim 6, characterized in that, The electron beam evaporation coating system includes an electron beam system and a thermal evaporation system; a chromium layer is deposited on the surface of the N-type tin oxide channel layer by the electron beam system, and a gold layer is deposited on the surface of the chromium layer by the thermal evaporation system to form the source electrode and the drain electrode; The thickness of the chromium layer is 15nm-25nm; and / or the thickness of the gold layer is 45nm-55nm.

8. A photodetector based on PVA-modulated SnO conductivity, prepared by the method according to any one of claims 1-7, characterized in that, The on / off ratio of the photodetector is not less than 3.0 × 10⁻⁶. 3 The migration rate is not less than 20 cm. 2 / V·s, dark current not greater than 1.0×10 -8 A; At a wavelength of 365nm and a light intensity of 1 W / cm² 2 Under ultraviolet light irradiation, the photoresponse rise time is no more than 0.5s and the fall time is no more than 1.0s.

9. The application of a photodetector prepared by the method of preparing a photodetector based on PVA-controlled SnO conductivity as described in any one of claims 1-7 in photoelectric detection and information processing in the ultraviolet band.

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