Nanocrystalline diamond heterojunction ultraviolet photoelectric detector

Abstract

The invention provides a nanocrystalline diamond heterojunction ultraviolet photoelectric detector, which is characterized in that seed crystal pretreatment is carried out on monocrystalline silicon, the obtained seed crystal monocrystalline silicon is used as a substrate, acetone is used as a carbon source, boron-doped nanocrystalline diamond is grown on the surface of the substrate by using a hot filament chemical vapor deposition method, the boron-doped nanocrystalline diamond is placed in a sulfuric acid solution, and the boron-doped nanocrystalline diamond heterojunction ultraviolet photoelectric detector is obtained. And performing cyclic voltammetry treatment. Then, the titanium source precursor is partially covered and placed in atomic layer deposition equipment, and deposition circulation is conducted through the titanium source precursor; and finally, the diamond and Ti areas are coated with silver paste to form an ohmic contact electrode, and the prepared nanocrystalline diamond heterojunction ultraviolet photoelectric detector has excellent response speed, can better adapt to high-speed ultraviolet detection tasks and shows good application prospects in the fields of ultraviolet communication, rapid switch monitoring and the like.

Description

(I) Technical Field

[0002] This invention relates to a nanocrystalline diamond heterojunction ultraviolet photodetector and a novel method for its fabrication. (II) Background Technology

[0004] In today's era of rapid technological advancement, ultraviolet (UV) photodetectors, as key photoelectric sensing elements, are widely used in numerous cutting-edge fields, such as environmental monitoring, biomedical imaging, flame detection, and military reconnaissance. In environmental monitoring, they can accurately monitor subtle changes in the ozone layer and the emission of harmful gases; in the biomedical field, they can be used for cell fluorescence detection and deep tissue imaging; in flame detection, they enable rapid response and real-time monitoring of flames; and militarily, they can be used for missile exhaust plume monitoring and battlefield reconnaissance, providing crucial support for national security and military strategy. However, with the ever-increasing demands for detection accuracy, response speed, and operational stability across various fields, traditional UV photodetectors have gradually revealed numerous limitations, making it difficult to meet the diverse needs of practical applications. To achieve high-performance UV detection, researchers are continuously exploring novel material systems and heterojunction structure designs to improve the photoresponsivity of devices, reduce dark current, and shorten response time.

[0005] Diamond, as a typical ultrawide bandgap semiconductor material, has shown great application potential in the field of ultraviolet photodetectors due to its excellent intrinsic physicochemical properties. Its ultra-high intrinsic carrier mobility enables high-speed response; its strong absorption characteristics in the ultraviolet band provide the foundation for high sensitivity; and its extremely high thermal conductivity ensures stable operation of devices under harsh environments such as high temperatures. However, the fabrication of high-quality, large-size single-crystal diamond is difficult and costly, and it is not easy to integrate with heterogeneous substrates, which severely limits its widespread application in photodetectors. To overcome these obstacles, nanocrystalline diamond films have emerged as a promising alternative material. They not only inherit most of the excellent properties of single-crystal diamond in terms of thermal conductivity, chemical stability, and ultraviolet absorption, but also possess advantages lacking in single-crystal materials: such as low-cost fabrication on large areas and various substrates, and better compatibility with existing microelectronic processes. Therefore, researchers at home and abroad have used nanocrystalline diamond films to fabricate ultraviolet photodetectors of various configurations and have conducted a series of studies on their photoelectric properties.

[0006] Lin et al. constructed a metal-semiconductor-metal (MSM) ultraviolet photodetector with a ZnO nanorod / nanodiamond film (ZNR / NDF) bilayer structure. This study involved growing a nanodiamond film on a glass substrate using microwave plasma chemical vapor deposition (MPCVD), followed by sputtering deposition of a ZnO seed layer and Au interdigitated electrodes. ZnO nanorods were then synthesized at 90 °C using a hydrothermal method to form a high-quality heterointerface. The device exhibited a high photoresponsivity of 594.6 and a dark current of 2.2 × 10⁻⁶ under 365 nm ultraviolet illumination. -3 The response and recovery times were 38.5 s and 1.1 s, respectively, significantly outperforming the single ZnO nanorod structure (217.1), validating the positive role of nanodiamond in controlling defects and suppressing carrier recombination. Building on this, Huang et al. introduced a low-temperature annealing process (150℃) to further optimize the ZNR / NDF heterojunction interface. Their study found that this treatment effectively improved the sp³ diamond quality and reduced the non-diamond component, thereby significantly suppressing the dark current to 1.76 × 10⁻⁶. -5 A, the photoresponse ratio was improved to 249.6 (about 6 times that of the unannealed sample), confirming the key influence of interface defect modulation on carrier transport behavior.

[0007] The team further proposed a novel heterostructure: graphene flakes dispersed into ZnO nanotubes on a discontinuous ultrananocrystalline diamond (UNCD) substrate (GrF-ZnTs / UNCD). This structure was achieved by preparing the UNCD substrate via MPECVD, preparing graphene using CVD and dispersing it into flakes, and then introducing GrF into the ZnO nanotubes using a soft hydrothermal method. Characterization showed that GrF was uniformly dispersed and that UNCD promoted the growth of highly oriented porous ZnTs. Photoelectric testing showed that the device achieved an ultra-high UV on / off ratio of 19,708 at a 5 V bias, far superior to single ZnTs (1,359), GrF-ZnTs (4,557), and ZnTs / UNCD (8,686), with a responsivity of 9.1 mA / W and response and recovery times of 48 s and 35 s, respectively, demonstrating excellent overall detection performance. This is mainly attributed to the synergistic effect of GrF and UNCD, which introduces a new conduction band level, lowers the potential barrier height, and promotes carrier transport. Furthermore, Saravanan et al. introduced a biopolymer modification strategy into detector design, using sericin (CSP) to coat ZnO nanorods and deposit them on a UNCD substrate to construct an SDZ core-shell heterostructure. This structure achieves a surface state density as high as 1.1 × 10⁻⁶ by modulating the surface state density through CSP and enhancing carrier transport with the help of UNCD. 5The UV light / dark current ratio and responsivity of 3.6 A / W, with response and recovery times of 0.59 s and 1.8 s respectively, demonstrate the great potential of biomaterial modification in balancing light absorption and carrier transport.

[0008] Nevertheless, the polycrystalline structure of nanocrystalline diamond films also presents new challenges. The presence of numerous grain boundaries and defects within nanocrystalline diamond films intensifies the scattering of photogenerated carriers, resulting in actual carrier mobility typically lower than the theoretical value for single-crystal diamond. Simultaneously, the high density of grain boundaries and defects hinders the effective collection of photogenerated carriers and induces significant dark currents. These issues collectively limit the detector's responsivity and signal-to-noise ratio, rendering existing devices unable to meet the demands of higher-performance ultraviolet detectors, necessitating further improvements. (III) Summary of the Invention

[0010] This invention provides a nanocrystalline diamond heterojunction ultraviolet photodetector. A boron-doped nanocrystalline diamond film is prepared using hot-filament chemical vapor deposition (HFCVD), then treated with cyclic voltammetry. Finally, TiO2 is deposited on the cyclically voltammetric boron-doped nanocrystalline diamond film using ALD to construct a heterojunction and fabricate the ultraviolet photodetector. This achieves reasonable bandgap matching, which is beneficial for carrier separation and transport, improving photoelectric conversion efficiency, and enhancing response capability and detection sensitivity. To achieve the above objectives, this invention adopts the following technical solution:

[0011] This invention provides a nanocrystalline diamond heterojunction ultraviolet photodetector, the preparation method of which is as follows:

[0012] (1) Seed crystal pretreatment is performed on monocrystalline silicon to obtain seeded monocrystalline silicon;

[0013] (2) Using the seeded single-crystal silicon described in step (1) as a substrate and acetone as a carbon source, boron-doped nanocrystalline diamond is grown on its surface by hot-wire chemical vapor deposition.

[0014] (3) The boron-doped nanocrystalline diamond described in step (2) is placed in a 0.1-1M (preferably 0.5M) H2SO4 aqueous solution, and cyclic voltammetry is used to scan the diamond at a scan rate of 50-200 mV / s (preferably 100 mV / s) within a voltage range of ±(3~6) V relative to the open circuit potential to obtain the boron-doped nanocrystalline diamond after cyclic voltammetry treatment.

[0015] (4) The boron-doped nanocrystalline diamond portion (preferably covered by a silicon wafer) after cyclic voltammetry treatment described in step (3) is placed in the atomic layer deposition equipment chamber. At a temperature of 200-300 ℃ (preferably 250 ℃), (the sample stage preheating time is set to 30-40 min (preferably 35 min)), 300-700 (preferably 500) atomic layer deposition cycles are performed using a titanium source precursor to obtain a diamond / TiO2 heterojunction. Each cycle includes: introducing the titanium source precursor, purging with an inert gas (preferably nitrogen), introducing water vapor and holding it, and purging with an inert gas again. The residence time of the titanium source precursor in the reaction chamber is 0.3-1.5 seconds (preferably 0.9 seconds), the inert gas purging time is 2-8 s (preferably 5 s), and the residence time of the water vapor in the chamber is 0.5-3.5 s (preferably 2 s). The time for the second inert gas flush is 6-10 seconds (preferably 8 seconds).

[0016] (5) Silver paste is coated on the diamond region and TiO2 region of the diamond / TiO2 heterojunction surface described in step (4) to form ohmic contact electrodes, thereby obtaining the nanocrystalline diamond heterojunction ultraviolet photodetector.

[0017] Further, the seed crystal pretreatment step in step (1) is as follows: diamond powder with a particle size of 3nm-1μm (preferably 500 nm) is mixed evenly with deionized water to obtain a diamond suspension. The diamond suspension is poured onto 400-2000 mesh (preferably 1500 mesh) sandpaper to obtain sandpaper with diamond suspension on its surface. The single-crystal silicon wafer is ground on the sandpaper with diamond suspension on its surface for 5-20 minutes (preferably 15 minutes). After being washed with deionized water, ultrasonically cleaned with deionized water, ultrasonically cleaned with alcohol, and dried with nitrogen, the seeded single-crystal silicon is obtained. The volume of the deionized water is 50-200 ml / g (preferably 100 ml / g) based on the mass of the diamond powder. The volume of the diamond suspension is 0.1-0.3 ml / cm² based on the area of ​​the sandpaper. 2 (Preferred concentration: 0.2 ml / cm) 2 ).

[0018] Further, the hot-wire chemical vapor deposition operation in step (2) is as follows: the single-crystal silicon seeded in step (1) is placed in a hot-wire chemical vapor deposition apparatus, and tantalum wire is used as the metal wire. Deposition and growth are carried out in a reaction atmosphere of methane, trimethyl borate, and hydrogen A. The growth power is controlled at 900-13000W (preferably 11000W), the growth pressure is 0.9-2 kPa (preferably 1.4 kPa), and the growth time is 1-6h (preferably 4h). After the deposition and growth are completed, boron-doped nanocrystalline diamond is obtained; the methane flow rate is 10-30 sccm (preferably 20 sccm). The boron source is trimethyl borate (in a boron source diluted 100 times, the mass ratio of trimethyl borate to acetone is 0.36:20; in a boron source diluted 150 times, the mass ratio of trimethyl borate to acetone is 0.24:20; and in a boron source diluted 200 times, the mass ratio of trimethyl borate to acetone is 0.18:20). Hydrogen B is introduced into the hot filament chemical vapor deposition equipment using hydrogen as a carrier. The flow rate of hydrogen B is 10-18 sccm (preferably 14 sccm), and the flow rate of hydrogen A is 100-900 sccm (preferably 500 sccm).

[0019] Furthermore, the carbon source flow rate is 20 sccm.

[0020] Furthermore, the flow rate of hydrogen B is 14 sccm.

[0021] Furthermore, the flow rate of hydrogen A mentioned in step 1 is 500 sccm.

[0022] Furthermore, the trimethyl borate is diluted 50-200 times (preferably 100 times) with acetone and introduced into the hot filament chemical vapor deposition equipment via a bubbling method using hydrogen as the carrier gas.

[0023] Furthermore, the deposition growth conditions are as follows: growth power 11000 W, growth pressure 1.4 kPa, and growth time 4 h.

[0024] Furthermore, the titanium source precursor mentioned in step (4) is tetra(dimethylamino)titanium, tetra(methylethylamino)titanium, tetraisopropoxide titanium or titanium tetrachloride (preferably tetraisopropoxide titanium).

[0025] Furthermore, the coating method described in step (5) is dot coating.

[0026] Compared with other types of diamond-based heterojunction detectors, the beneficial effects of this invention are: 1) Significantly improved detector response speed. Under 254 nm ultraviolet light irradiation, the fastest response speed of this invention is 0.068 s, which is an order of magnitude faster than the response speed of similar detectors. 2) The fabrication process has advantages such as simple steps and ease of industrial implementation. (iv) Description of the attached drawings

[0028] Figure 1 The Raman spectrum of BDD grown by diluting the boron source 100 times in Example 1 after CV±3V voltage treatment.

[0029] Figure 2 The image shows a SEM image of BDD grown from a boron source diluted 100 times in Example 1 after CV ± 3V voltage treatment.

[0030] Figure 3 In Example 1, a BDD grown by diluting the boron source by 100 times was subjected to CV±3V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the IV curve of the ultraviolet photodetector.

[0031] Figure 4 In Example 1, a BDD grown by diluting the boron source 100 times was subjected to CV±3V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the response curve of the ultraviolet photodetector.

[0032] Figure 5 The Raman spectrum of BDD grown by diluting the boron source 100 times in Example 2 after CV±4V voltage treatment.

[0033] Figure 6 This is a SEM image of BDD grown from a boron source diluted 100 times in Example 2, after being treated with CV ± 4V voltage.

[0034] Figure 7 In Example 2, a BDD grown by diluting the boron source 100 times was subjected to CV±4V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction and prepare the IV curve of the ultraviolet photodetector.

[0035] Figure 8 In Example 2, a BDD grown by diluting the boron source 100 times was subjected to CV±4V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry by ALD to construct a heterojunction and prepare the response curve of the ultraviolet photodetector.

[0036] Figure 9 The Raman spectrum of BDD grown by diluting the boron source 100 times in Example 3 after being treated with CV ± 6V voltage.

[0037] Figure 10 This is a SEM image of BDD grown from a boron source diluted 100 times in Example 3, after being treated with CV ± 6V voltage.

[0038] Figure 11 In Example 3, a BDD grown by diluting the boron source 100 times was subjected to CV±6V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the IV curve of the ultraviolet photodetector.

[0039] Figure 12 In Example 3, a BDD grown by diluting the boron source 100 times was subjected to CVZ±6V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the response curve of the ultraviolet photodetector.

[0040] Figure 13 The Raman spectrum of BDD grown by diluting the boron source 150 times in Example 4 after CV±3V voltage treatment.

[0041] Figure 14 This is a SEM image of BDD grown from a boron source diluted 150 times in Example 4 after CV ± 3V voltage treatment.

[0042] Figure 15 In Example 4, a BDD grown by diluting the boron source by 150 times was subjected to CV±3V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the IV curve of the ultraviolet photodetector.

[0043] Figure 16 In Example 4, a BDD grown by diluting the boron source by 150 times was subjected to CV±3V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the response curve of the ultraviolet photodetector.

[0044] Figure 17 The Raman spectrum of BDD grown by diluting the boron source 150 times in Example 5 after CV±4V voltage treatment.

[0045] Figure 18 This is a SEM image of BDD grown from a boron source diluted 150 times in Example 5, after being treated with CV ± 4V voltage.

[0046] Figure 19 In Example 5, a BDD grown by diluting the boron source by 150 times was subjected to CV±4V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the IV curve of the ultraviolet photodetector.

[0047] Figure 20In Example 5, a BDD grown by diluting the boron source by 150 times was subjected to CVZ±4V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry via ALD to construct a heterojunction and prepare the response curve of the ultraviolet photodetector.

[0048] Figure 21 The Raman spectrum of BDD grown by diluting the boron source 150 times in Example 6 after CV ± 6V voltage treatment.

[0049] Figure 22 This is a SEM image of BDD grown from a boron source diluted 150 times in Example 6, after being treated with CV ± 6V voltage.

[0050] Figure 23 In Example 6, a BDD grown by diluting the boron source by 150 times was subjected to CV±6V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry via ALD to construct a heterojunction and prepare the IV curve of an ultraviolet photodetector.

[0051] Figure 24 In Example 6, a BDD grown by diluting the boron source by 150 times was subjected to CV±6V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the response curve of the ultraviolet photodetector.

[0052] Figure 25 The Raman spectrum of BDD grown by diluting the boron source 200 times in Example 7 after CV±3V voltage treatment.

[0053] Figure 26 This is a SEM image of BDD grown from a boron source diluted 200 times in Example 7, after being treated with CV ± 3V voltage.

[0054] Figure 27 In Example 7, a BDD grown by diluting the boron source by 200 times was subjected to CV±3V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction and prepare the IV curve of the ultraviolet photodetector.

[0055] Figure 28 In Example 7, a BDD grown by diluting the boron source by 200 times was subjected to CVZ±3V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry via ALD to construct a heterojunction and prepare the response curve of the ultraviolet photodetector.

[0056] Figure 29 The Raman spectrum of BDD grown by diluting the boron source 200 times in Example 8 after CV±4V voltage treatment.

[0057] Figure 30 This is a SEM image of BDD grown from a boron source diluted 200 times in Example 8 after CV ± 4V voltage treatment.

[0058] Figure 31 In Example 8, a BDD grown by diluting the boron source by 200 times was subjected to CV±4V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction and prepare the IV curve of the ultraviolet photodetector.

[0059] Figure 32 In Example 8, a BDD grown by diluting the boron source by 200 times was subjected to CV±4V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry by ALD to construct a heterojunction and prepare the response curve of the ultraviolet photodetector.

[0060] Figure 33 The Raman spectrum of BDD grown by diluting the boron source 200 times in Example 9 after being treated with CV ± 6V voltage.

[0061] Figure 34 This is a SEM image of BDD grown from a boron source diluted 200 times in Example 9 after CV ± 6V voltage treatment.

[0062] Figure 35 In Example 9, a BDD grown by diluting the boron source by 200 times was subjected to CV±6V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry to construct a heterojunction to prepare the IV curve of the ultraviolet photodetector.

[0063] Figure 36 In Example 9, a BDD grown by diluting the boron source by 200 times was subjected to CV±6V voltage treatment, and then TiO2 was deposited on the BDD treated by cyclic voltammetry by ALD to construct a heterojunction and prepare the response curve of the ultraviolet photodetector. (V) Detailed Implementation

[0065] The present invention will be further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0066] Example 1

[0067] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0068] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension onto 1500-grit sandpaper with a diameter of 644 cm. 2Take a cut single crystal silicon wafer (approximately 2×2 cm in size, resistivity 0.011-0.01 Ωcm, p-type (100) crystal plane, hereinafter referred to as silicon wafer) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, take out the silicon wafer and finally blow it dry with high-purity nitrogen to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0069] (3) Preparation of boron-doped nanocrystalline diamond: The seeded silicon wafer from step (2) was placed in a hot-wire chemical vapor deposition apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 100. The mass ratio of trimethyl borate to acetone in the boron source was 0.36:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0070] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±3 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0071] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0072] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03Ω / sq) is applied to the four corners of the thin film by capillary tubes on the two parts of the diamond / TiO2 heterojunction. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0073] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0074] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0075] Figure 1 The Raman spectrum of Example 1 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where C d and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 1 The diamond content in Example 1 can be calculated to be 11.56%.

[0076] Figure 2 The SEM image of Example 1 shows that the surface consists of irregular tiny nanoparticles.

[0077] Figure 3 The IV curve for Example 1 shows a detector dark current of 2.56027 × 10⁻⁶. -6 A, The difference between light and dark current at 5V is 1.18.

[0078] Figure 4The response curve for Example 1 shows that the detector can produce a significant response to ultraviolet light, with a response time of 0.085 s and a recovery time of 1.014 s, which is an order of magnitude better than other types of diamond-based heterojunction detectors.

[0079] Example 2

[0080] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0081] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0082] (3) Preparation of boron-doped nanocrystalline diamond: The seeded silicon wafer from step (2) was placed in a hot-wire chemical vapor deposition apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 100. The mass ratio of trimethyl borate to acetone in the boron source was 0.36:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0083] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±4 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0084] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0085] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0086] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0087] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0088] Figure 5 The Raman spectrum of Example 2 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where Cd and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 5 The diamond content in Example 2 can be calculated to be 18.49%.

[0089] Figure 6 The SEM image of Example 2 shows that the surface consists of irregular tiny nanoparticles.

[0090] Figure 7 The IV curve for Example 2 shows a detector dark current of 3.08882 × 10⁻⁶. -6 A, the difference between light and dark current at 5V is 11.53.

[0091] Figure 8 The response curve for Example 2 shows that the detector can produce a significant response to ultraviolet light, with a response time of 0.212 s and a recovery time of 0.458 s, which is an improvement compared to other types of diamond-based heterojunction detectors.

[0092] Example 3

[0093] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0094] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0095] (3) Preparation of boron-doped nanocrystalline diamond: The seeded silicon wafer from step (2) was placed in a hot-wire chemical vapor deposition apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 100. The mass ratio of trimethyl borate to acetone in the boron source was 0.36:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0096] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±6 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0097] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0098] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0099] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0100] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0101] Figure 9The Raman spectrum of Example 3 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where C d and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 9 The diamond content in Example 3 can be calculated to be 23.68%.

[0102] Figure 10 The SEM image of Example 3 shows that the surface consists of irregular tiny nanoparticles.

[0103] Figure 11 The IV curve for Example 3 shows a detector dark current of 3.15169 × 10⁻⁶. -6 A, The difference between light and dark current at 5V is 5.58.

[0104] Figure 12 The response curve for Example 3 shows that the detector can produce a significant response to ultraviolet light, with a response time of 0.068 s and a recovery time of 0.889 s, which is an order of magnitude better than other types of diamond-based heterojunction detectors.

[0105] Example 4

[0106] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0107] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0108] (3) Preparation of boron-doped nanocrystalline diamond: The seeded silicon wafer from step (2) was placed in a hot-wire chemical vapor deposition (HCV) apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 150. The mass ratio of trimethyl borate to acetone in the boron source was 0.24:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0109] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±3 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0110] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0111] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0112] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0113] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0114] Figure 13 The Raman spectrum of Example 4 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where C d and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 13 The diamond content in Example 4 can be calculated to be 27.04%.

[0115] Figure 14 The SEM image of Example 4 shows that the surface consists of irregular tiny nanoparticles.

[0116] Figure 15 The IV curve for Example 4 shows a detector dark current of 5.72617 × 10⁻⁶. -6 A, the difference between light and dark current at 5V is 37.71.

[0117] Figure 16The response curve for Example 4 shows that the detector can produce a significant response to ultraviolet light, with a response time of 1.52 s and a recovery time of 0.46 s, which is an improvement compared to other types of diamond-based heterojunction detectors.

[0118] Example 5

[0119] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0120] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0121] (3) Preparation of boron-doped nanocrystalline diamond: The seeded silicon wafer from step (2) was placed in a hot-wire chemical vapor deposition (HCV) apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 150. The mass ratio of trimethyl borate to acetone in the boron source was 0.24:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0122] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±4 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0123] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0124] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0125] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0126] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0127] Figure 17 The Raman spectrum of Example 5 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where Cd and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 17 The diamond content in Example 5 can be calculated to be 25.21%.

[0128] Figure 18 The SEM image of Example 5 shows that the surface consists of irregular tiny nanoparticles.

[0129] Figure 19 The IV curve for Example 5 shows a detector dark current of 6.51702 × 10⁻⁶. -6 A, the difference between light and dark current at 5V is 21.67.

[0130] Figure 20 The response curve for Example 5 shows that the detector can produce a significant response to ultraviolet light, with a response time of 1.39 s and a recovery time of 0.14 s, which is an improvement compared to other types of diamond-based heterojunction detectors.

[0131] Example 6

[0132] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0133] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0134] (3) Preparation of boron-doped nanocrystalline diamond: The seeded silicon wafer from step (2) was placed in a hot-wire chemical vapor deposition (HCV) apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 150. The mass ratio of trimethyl borate to acetone in the boron source was 0.24:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0135] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±6 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0136] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0137] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0138] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0139] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0140] Figure 21The Raman spectrum of Example 6 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where C d and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 21 The diamond content in Example 6 can be calculated to be 31.81%.

[0141] Figure 22 The SEM image of Example 6 shows that the surface consists of irregular tiny nanoparticles.

[0142] Figure 23 The IV curve for Example 6 shows a detector dark current of 9.53617 × 10⁻⁶. -6 A, the difference between light and dark current at 5V is 21.46.

[0143] Figure 24 The response curve for Example 6 shows that the detector can produce a significant response to ultraviolet light, with a response time of 1.03 s and a recovery time of 0.21 s, which is an improvement compared to other types of diamond-based heterojunction detectors.

[0144] Example 7

[0145] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0146] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0147] (3) Preparation of boron-doped nanocrystalline diamond: The silicon wafer after seeding in step (2) was placed in a hot-wire chemical vapor deposition apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 200. The mass ratio of trimethyl borate to acetone in the boron source was 0.18:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0148] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±3 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0149] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0150] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0151] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0152] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0153] Figure 25 The Raman spectrum of Example 7 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where C d and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 25 The diamond content in Example 7 can be calculated to be 23.82%.

[0154] Figure 26 The SEM image of Example 7 shows that the surface consists of irregular tiny nanoparticles.

[0155] Figure 27 The IV curve for Example 7 shows a detector dark current of 5.48948 × 10⁻⁶. -7 A, The difference between light and dark current at 5V is 4.29.

[0156] Figure 28The response curve for Example 7 shows that the detector can produce a significant response to ultraviolet light, with a response time of 2.706 s and a recovery time of 0.860 s, which is at the same level as other types of diamond-based heterojunction detectors.

[0157] Example 8

[0158] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0159] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0160] (3) Preparation of boron-doped nanocrystalline diamond: The silicon wafer after seeding in step (2) was placed in a hot-wire chemical vapor deposition apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 200. The mass ratio of trimethyl borate to acetone in the boron source was 0.18:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0161] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±4 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0162] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0163] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0164] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0165] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0166] Figure 29 The Raman spectrum of Example 8 is mainly composed of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where Cd and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 29 The diamond content in Example 8 can be calculated to be 29.55%.

[0167] Figure 30 The SEM image of Example 8 shows that the surface consists of irregular tiny nanoparticles.

[0168] Figure 31 The IV curve for Example 8 shows a detector dark current of 9.3312 × 10⁻⁶. -7 A, The difference between light and dark current at 5V is 4.74.

[0169] Figure 32 The response curve for Example 8 shows that the detector can produce a significant response to ultraviolet light, with a response time of 1.436 s and a recovery time of 1.059 s. Compared with other types of diamond-based heterojunction detectors, there is still room for improvement in performance.

[0170] Example 9

[0171] (1) Preparation of diamond suspension: Mix 0.3 g of diamond powder with a particle size of 500 nm and 30 ml of deionized water at a ratio of 1 g: 100 ml and stir thoroughly to obtain diamond suspension.

[0172] (2) Polishing the seed crystal: Pour 30 ml of the prepared diamond suspension as polishing solution onto 1500-grit sandpaper with a diameter of 644 cm. 2 Take the cut silicon wafer (approximately 2×2 cm in size) and polish it on sandpaper for 15 minutes. Clean the polished silicon wafer with deionized water, and then place it in deionized water and alcohol for ultrasonic cleaning for 5 minutes in sequence. After ultrasonic cleaning, remove the silicon wafer and finally dry it with high-purity nitrogen gas to obtain a silicon wafer with a dense seed crystal layer on the surface.

[0173] (3) Preparation of boron-doped nanocrystalline diamond: The silicon wafer after seeding in step (2) was placed in a hot-wire chemical vapor deposition apparatus. Tantalum wire was used as the metal wire, methane was used as the carbon source with a flow rate of 20 sccm, and trimethyl borate was used as the boron source. The doping concentration was controlled by dilution with acetone at a dilution factor of 200. The mass ratio of trimethyl borate to acetone in the boron source was 0.18:20 g, and the boron source flow rate was 14 sccm. High-purity hydrogen gas was bubbled into the reaction chamber, and high-purity hydrogen gas with a flow rate of 500 sccm was also introduced. The growth power was controlled at 11000 W, the growth pressure at 1.4 kPa, and the growth time at 4.0 h. Then the pure hydrogen gas was stopped, and the temperature was lowered for 30 min to obtain boron-doped nanocrystalline diamond.

[0174] (4) Cyclic voltammetry treatment: The boron-doped nanocrystalline diamond prepared in step (3) was placed in H2SO4 solution with a concentration of 0.5 M. The cyclic voltammetry scan range was set to ±6 V and the scan rate to 100 mV / s. The electrochemical workstation was then connected to perform cyclic voltammetry treatment.

[0175] (5) ALD deposition of TiO2 to construct heterojunction: The sample after cyclic voltammetry treatment in step (4) was placed in the chamber of the atomic layer deposition equipment and half of it was covered with a silicon wafer. The sample stage temperature was set to 250 ℃, the sample stage preheating time was 35 minutes, the number of atomic layer deposition cycles was 500, the residence time of the precursor titanium source (tetraisopropoxide titanium) was 0.9 s, the nitrogen rinsing time was 5 s, the water residence time in the chamber was 2 s, and the nitrogen rinsing time was 8 s. After deposition, a diamond / TiO2 heterojunction was obtained.

[0176] (6) Electrode construction: In step (5), conductive silver coating (purchased from CAIG, USA, model CW-200B, surface resistance 0.01-0.03 Ω / sq) is applied to the two parts of the diamond / TiO2 heterojunction using capillary tubes. Then, the silver electrode is dried at room temperature to form an ohmic contact electrode, thus preparing an ultraviolet photodetector with a silver / diamond-TiO2 heterojunction / silver structure.

[0177] (7) Test photoelectric performance: Irradiate the ultraviolet photodetector obtained in step (6) with ultraviolet light with a wavelength of 254 nm, and test the photoelectric performance of the detector using a semiconductor four-probe test system.

[0178] The composition of the material was detected by Raman spectroscopy, the surface morphology of the material was observed by field emission scanning electron microscopy, and the photoelectric performance of the detector was tested by a semiconductor four-probe and 254 nm ultraviolet light.

[0179] Figure 33The Raman spectrum of Example 9 mainly consists of 1140, 1250, 1332, 1350, 1470, and 1580 cm⁻¹. -1 The spectrum consists of six characteristic peaks, representing a typical Raman spectrum of nanodiamond films. The peak at 1140 cm⁻¹ is particularly prominent. -1 and 1470 cm -1 The peak at the point is attributed to the sp of TPA at the grain boundary. 2 CC vibration, 1250 cm -1 The peak at 1332 cm⁻¹ is caused by the broadened vibrational density of diamond clusters with small grain size and tetrahedral amorphous carbon. -1 The peak at this location is a typical diamond-like peak, 1350 cm high. -1 The D peak at the point of intersection with the disordered graphite grain boundaries or other structural defects at the sp peak is located at the point of intersection. 2 Related to the stretching vibration of the bond, 1580 cm -1 The G peak at that location is formed by sp in the plane of a highly graphitized six-membered ring. 2 Produced by the vibration of hybrid C-C bonds. (via formula) The content of the diamond phase in the thin-film electrode can be calculated, where C d and C i These are Raman spectra from 800 to 2200 cm⁻¹. -1 The integral area of ​​the mid-diamond peak and the non-diamond phase peak; according to Figure 33 The diamond content in Example 9 can be calculated to be 22.94%.

[0180] Figure 34 The SEM image of Example 9 shows that the surface consists of irregular tiny nanoparticles.

[0181] Figure 35 The IV curve for Example 9 shows a detector dark current of 5.60288 × 10⁻⁶. -7 A, The difference between light and dark current at 5V is 5.72.

[0182] Figure 36 The response curve for Example 9 shows that the detector can produce a significant response to ultraviolet light, with a response time of 0.938 s and a recovery time of 1.043 s, which is at the same level as other types of diamond-based heterojunction detectors.

Claims

1. A nanocrystalline diamond heterojunction ultraviolet photodetector, characterized in that, The preparation method is as follows: (1) Seed crystal pretreatment is performed on monocrystalline silicon to obtain seeded monocrystalline silicon; (2) Using the seeded single-crystal silicon described in step (1) as a substrate, and acetone as a carbon source, boron-doped nanocrystalline diamond is grown on its surface by hot-wire chemical vapor deposition. (3) Place the boron-doped nanocrystalline diamond described in step (2) in a 0.1-1M H2SO4 aqueous solution and perform cyclic voltammetry at a scanning rate of 50-200 mV / s within a voltage range of ±(3~6) V relative to the open circuit potential to obtain the boron-doped nanocrystalline diamond after cyclic voltammetry treatment. (4) The boron-doped nanocrystalline diamond covered part after the cyclic voltammetry treatment in step (3) is placed in the chamber of the atomic layer deposition equipment. At a temperature of 200-300 °C, 300-700 atomic layer deposition cycles are performed using a titanium source precursor to obtain a diamond / TiO2 heterojunction. A single cycle includes: introducing a titanium source precursor, purging with an inert gas, introducing water vapor and allowing it to remain in the chamber, and purging with an inert gas again; the residence time of the titanium source precursor in the reaction chamber is 0.3-1.5 seconds, the purging time with an inert gas is 2-8 seconds, the residence time of the water vapor in the chamber is 0.5-3.5 seconds, and the time for the second inert gas purging is 6-10 seconds; (5) Silver paste is coated on the diamond region and TiO2 region of the diamond / TiO2 heterojunction surface described in step (4) to form ohmic contact electrodes, thereby obtaining the nanocrystalline diamond heterojunction ultraviolet photodetector.

2. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 1, characterized in that, The seed crystal pretreatment steps in step (1) are as follows: Diamond powder with a particle size of 3nm-1μm is mixed evenly with deionized water to obtain a diamond suspension. The diamond suspension is poured onto 400-2000 mesh sandpaper to obtain sandpaper with the diamond suspension on its surface. The single-crystal silicon wafer is ground on the sandpaper with the diamond suspension on its surface for 5-20 minutes. After washing with deionized water, ultrasonic cleaning with deionized water, ultrasonic cleaning with alcohol, and drying with nitrogen, the seeded single-crystal silicon is obtained. The volume of the deionized water is 50-200 ml / g based on the mass of the diamond powder. The volume of the diamond suspension is 0.1-0.3 ml / cm² based on the area of ​​the sandpaper. 2 .

3. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 1, characterized in that, The hot-wire chemical vapor deposition operation described in step (2) is as follows: The single-crystal silicon seeded in step (1) is placed in the hot-wire chemical vapor deposition equipment, and tantalum wire is used as the metal wire. Deposition and growth are carried out in the reaction atmosphere of methane, trimethyl borate, and hydrogen A. The growth power is controlled at 900-13000W, the growth pressure is 0.9-2 kPa, and the growth time is 1-6h. After the deposition and growth are completed, boron-doped nanocrystalline diamond is obtained. The flow rate of methane is 10-30 sccm. The trimethyl borate is introduced into the hot-wire chemical vapor deposition equipment with hydrogen B as the carrier. The flow rate of hydrogen B is 10-18 sccm, and the flow rate of hydrogen A is 100-900 sccm.

4. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 3, characterized in that, The carbon source flow rate is 20 sccm.

5. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 3, characterized in that, The flow rate of hydrogen B is 14 sccm.

6. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 3, characterized in that, The flow rate of hydrogen A mentioned in step A is 500 sccm.

7. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 3, characterized in that, The trimethyl borate is diluted 50-200 times with acetone and introduced into the hot filament chemical vapor deposition equipment via a bubbling method using hydrogen as the carrier gas.

8. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 3, characterized in that, The deposition growth conditions were: growth power 11000 W, growth pressure 1.4 kPa, and growth time 4 h.

9. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 1, characterized in that, The titanium source precursor mentioned in step (4) is tetra(dimethylamino)titanium, tetra(methylethylamino)titanium, tetraisopropoxide titanium or titanium tetrachloride.

10. The nanocrystalline diamond heterojunction ultraviolet photodetector as described in claim 1, characterized in that, The coating method described in step (5) is dot coating.

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