A single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, a preparation method and application in a self-powered solar blind detector

Abstract

A single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, a preparation method and application in a self-powered solar blind detector belong to the technical field of semiconductor detectors.The single-phase oxide ferroelectric semiconductor thin film is composed of a ZnO thin film co-doped with Mg, Al and Li as an active absorption layer and a silicon substrate, is prepared through a co-doping strategy of Mg, Al and Li, and is applied in a solar blind detector through a matching electric field heat treatment process, so that the band gap of pure ZnO is effectively widened to the solar blind region, the built-in electric field generated by the donor-acceptor defect dipole constructed in the crystal lattice is utilized, and the high insulating state of the material is maintained through the charge compensation effect, so that the high-performance self-powered solar blind ultraviolet detection with low dark current, high responsivity and high on-off ratio is realized under zero applied bias.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor detector technology, and relates to a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, its preparation method, and its application in a self-powered solar-blind detector. Background Technology

[0002] In the electromagnetic spectrum, deep ultraviolet (UVC) radiation with wavelengths between 200 nm and 280 nm is strongly absorbed by the ozone layer in the stratosphere, causing solar radiation in this band to almost never reach the Earth's surface; this is known as the "solar blind zone." Because there is virtually no natural solar blind ultraviolet background radiation at the Earth's surface, detectors operating in this band possess extremely high signal-to-noise ratios and extremely low false alarm rates. This "zero background noise" characteristic makes solar blind ultraviolet detection irreplaceable in strategic fields such as missile plume early warning, shipborne ultraviolet warning, power grid corona monitoring, and secure optical communications.

[0003] The working principle of semiconductor optoelectronic devices is that the material absorbs incident photons and generates photogenerated carriers, which are then separated and transported under the influence of an electric field, ultimately forming a captureable electrical signal. For related devices, the band gap, band structure, defect type and concentration, carrier mobility, impurity compensation relationship, and built-in field distribution of the semiconductor material usually jointly determine its key performance indicators such as absorption cutoff edge, dark current, response speed, selectivity, and stability. Zinc oxide (ZnO) is a representative group II–VI wide band gap oxide semiconductor, usually exhibiting a wurtzite structure. ZnO has a wide band gap, good chemical stability and radiation stability, and is easy to construct semiconductor functional layers through thin films or epitaxy, thus attracting widespread attention in ultraviolet optoelectronic devices. However, the absorption edge and band position of pure ZnO are still limited by its intrinsic band gap. When it is necessary to further extend the absorption cutoff edge to shorter wavelengths, it is usually necessary to use doping to control its band gap structure. Meanwhile, traditional ZnO-based photodetectors mostly employ photoconductive structures, which heavily rely on external bias voltage to drive the separation and transport of photogenerated carriers. External bias voltage not only increases system power consumption and integration complexity but also significantly increases dark current and introduces substantial electrical noise, directly undermining the extremely low noise advantage sought in photodetectors. Therefore, developing self-powered photodetectors operating under zero bias voltage has become an urgent need in this field.

[0004] To overcome the aforementioned problems and effectively detect light in the solar-blind band, the existing technical approach involves introducing Mg into ZnO to form ZnO. 1-x Mg xThe O-system aims to broaden the bandgap and achieve a blue shift of the absorption edge. However, to achieve self-powered operation, traditional built-in electric field construction often relies on complex heterojunctions or multiphase composite systems. This inevitably introduces numerous interface defects and grain boundary scattering, becoming a constraint on the signal-to-noise ratio and response speed of the device. Therefore, constructing single-phase self-powered solar-blind ultraviolet detectors has become an emerging research direction. Existing studies have found that ZnO generates a certain amount of intrinsic defects such as zinc vacancies and oxygen vacancies during growth, thereby inducing a weak self-polarization phenomenon. However, this built-in electric field based on intrinsic defects is passively generated and extremely uncontrollable, with very weak local ferroelectricity, resulting in slow detector response speed and extremely low photocurrent. Therefore, inducing polarization by doping with other components to obtain a stronger and controllable polarization electric field to generate local ferroelectricity and achieve self-powered operation has become a potential strategy. However, this approach faces a serious physical contradiction: if donor elements are simply doped into ZnO, although it can cause some lattice distortion, it will release a large number of free electrons, leading to a surge in the conductivity of the material. In the macroscopic performance of the detector, this will cause the dark current to surge exponentially, the on / off ratio of the device to deteriorate drastically, or even fail directly. On the other hand, if acceptor elements are simply doped, it will face an extremely high compensation energy barrier.

[0005] In summary, there is currently a lack of a ZnO-based ultraviolet detection technology that can actively and controllably construct local ferroelectricity within the crystal lattice to achieve self-powering. Summary of the Invention

[0006] The purpose of this invention is to overcome the technical defects of existing zinc oxide-based ultraviolet detectors, such as narrow bandgap that cannot meet the requirements of solar-blind detection, reliance on external bias voltage leading to high power consumption and low signal-to-noise ratio, easy dark current surge if single-doped induced polarization is performed, and difficulty in P-type doping. The invention provides a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, its preparation method, and its application in a self-powered solar-blind detector.

[0007] To achieve the above objectives, the following technical solution is adopted:

[0008] The first aspect of this invention provides a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, comprising a silicon substrate and an active absorption layer grown on the silicon substrate, wherein the active absorption layer is a ZnO thin film co-doped with Mg, Al, and Li, and its general chemical formula is Mg 0.3 Al x Li x Zn 0.7-2x O, where x = 0.01~0.07; the thickness of the ZnO film is 200nm~250nm.

[0009] In the ZnO thin film, Al 3+ As a benefactor, Li+ As acceptors, the two form adjacent defect ion pairs at the Zn site, inducing local symmetry breaking and forming an electric dipole moment. Subsequently, electric field heat treatment causes the ion pairs to flip in an oriented manner, forming a local self-built electric field.

[0010] The present invention also provides a method for preparing the single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, comprising the following steps:

[0011] Step 1: Weigh zinc acetate and dissolve it in ethylene glycol methyl ether under the action of the complexing agent ethanolamine. Stir the resulting solution at 55℃~65℃ for 1h~2h until a clear precursor solution is formed.

[0012] Step 2: Under water bath heating and stirring conditions, magnesium acetate, anhydrous lithium acetate, and aluminum nitrate, the dopant sources, are added sequentially to the precursor solution. After each reagent is added, the mixture is stirred for 0.5 h to 1 h to form a clear and uniform sol. The concentration of the sol is controlled at 0.3 mol / L to 0.4 mol / L. The water bath heating temperature is 55℃ to 65℃.

[0013] Step 3: Aging the sol obtained in Step 2 at room temperature for more than 24 hours to form a colloid.

[0014] Step 4: Coat a thin film on a cleaned silicon substrate using the sol-gel method. First, spin coat the colloid at a speed of 1500 r / s to 2000 r / s for 5 to 10 seconds, and then spin coat at a speed of 3500 r / s to 4000 r / s for 10 to 15 seconds to ensure the uniformity of the film.

[0015] Step 5: Pyrolysis at 180℃~220℃ for 1min~5min to evaporate organic solvents and moisture.

[0016] Step Six: Repeat Steps Four and Five until the ZnO film reaches the target thickness.

[0017] Step 7: The ZnO thin film is crystallized in a rapid thermal annealing (RTA) furnace to obtain a single-phase oxide ferroelectric semiconductor thin film; wherein the processing temperature is 600℃~700℃ and the crystallization time is 5min~10min.

[0018] The third aspect provides the application of the semiconductor of the ZnO thin film in a solar-blind detector, including the following steps:

[0019] S1: Interdigitated electrodes are deposited on the surface of a ZnO semiconductor thin film using DC magnetron sputtering to obtain a thin-film device. The area of ​​the interdigitated electrodes is matched with the area of ​​the ZnO semiconductor thin film.

[0020] S2: The prepared thin-film device is subjected to electric field polarization treatment under certain temperature and electric field conditions. The polarization temperature is 180℃-200℃, the polarization time is 5h-8h, and the polarization electric field strength is 70kV / cm-80kV / cm. Subsequently, it is naturally cooled to room temperature in the electric field to obtain a self-powered solar-blind detector with a built-in electric field after polarization.

[0021] The solar-blind detector has a maximum light-to-dark ratio of 8031, a maximum responsivity of 36.45 mA / W, and a minimum transient response time of 11 ms.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention proposes a ZnO-based solar-blind ultraviolet detector film co-doped with Mg, Al, and Li. Mg is used to modulate the bandgap of the ZnO substrate, shifting its absorption cutoff edge towards the solar-blind ultraviolet band. Simultaneously, Al is introduced... 3+ -Li + As donor-acceptor co-doped ions, Al forms donor-acceptor defect ion pairs in the ZnO lattice. These defect ion pairs can cause local lattice distortion and local symmetry breaking, and form corresponding defect dipoles. Without polarization treatment, Al... 3+ -Li + The orientation distribution of defect ion pairs and their defect dipoles is relatively random, making it difficult to form a stable and effective macroscopic built-in electric field. This invention further employs an electric field heat treatment process to promote the directional alignment of defect dipoles under certain temperature and applied electric field conditions, thereby forming a built-in electric field within the thin film that facilitates the separation of photogenerated carriers, enabling the device to generate a measurable photoelectric response under zero applied bias. On the other hand, Al... 3+ As donor ions, Li readily introduces electrons into the ZnO matrix, and when used alone as a dopant, it may lead to an increase in the free carrier concentration of the thin film and an increase in dark current; + As an acceptor ion, it can bind to Al 3+ The introduced electrons compensate for the loss, maintaining the film at a high resistance, thereby suppressing dark current.

[0024] This invention utilizes a synergistic co-doping strategy of Mg, Al, and Li elements and a corresponding electric field thermal treatment process to effectively broaden the band gap of pure ZnO into the solar blind region. At the same time, it leverages the built-in electric field generated by the donor-acceptor defect dipoles constructed within the crystal lattice and maintains the high insulating state of the material with the help of charge compensation effect. This enables high-performance self-powered solar blind ultraviolet detection with low dark current, high responsivity, and high on / off ratio under zero applied bias voltage. Attached Figure Description

[0025] Figure 1 A schematic diagram of the self-powered solar-blind detector structure provided by this invention;

[0026] Figure 2 Al 3+ Li + Schematic diagram of the difference in electron density around an ion and the corresponding dipole moment;

[0027] Figure 3 The It curve of the solar-blind detector under zero bias obtained in Comparative Example 1 of this invention;

[0028] Figure 4 The It curve of the solar-blind detector under zero bias obtained in Embodiment 1 of the present invention;

[0029] Figure 5 The It curve of the solar-blind detector under zero bias obtained in Embodiment 2 of the present invention;

[0030] Figure 6 The It curve of the solar-blind detector under zero bias obtained in Embodiment 3 of the present invention;

[0031] Figure 7 The It curve of the solar-blind detector under zero bias obtained in Example 4 of this invention;

[0032] Figure 8 The relationship between the response current and time of the MALZO solar-blind detector to UVC / UVA obtained in Embodiment 2 of the present invention;

[0033] Figure 9 XRD results of crystals in thin films obtained from different embodiments and comparative examples;

[0034] Figure 10 Hysteresis loop diagram of the single-phase oxide ferroelectric semiconductor thin film obtained in Example 2 of the present invention. Detailed Implementation

[0035] The present invention provides a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, comprising a silicon substrate and an active absorption layer grown on the silicon substrate.

[0036] The single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio provided by this invention has an active absorber layer that is a 200nm~250nm thick ZnO thin film co-doped with Mg, Al, and Li, and its general chemical formula is Mg 0.3 Al x Li x Zn 0.7-2x O, where x is the doping amount, x = 0.01~0.07.

[0037] The present invention also provides a method for preparing the single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, comprising the following steps:

[0038] (1) Weigh out zinc acetate and ethanolamine respectively, dissolve them in ethylene glycol methyl ether, and stir at 55℃~65℃ for 1h~2h until a clear precursor solution is formed.

[0039] (2) Under the conditions of stirring in a water bath at 55℃~65℃, magnesium acetate, lithium acetate and aluminum nitrate are added to the precursor solution in sequence. After each reagent is added, the mixture is stirred for 0.5h~1h to finally form a clear sol with a concentration of 0.3mol / L~0.4mol / L.

[0040] (3) The sol is aged at room temperature for more than 24 hours to form a colloid.

[0041] (4) Using spin coating, the colloid is first spin coated at a speed of 1500r / s~2000r / s for 5s~10s, and then spin coated at a speed of 3500r / s~4000r / s for 10s~15s to obtain a film with uniform thickness.

[0042] (5) Pyrolyze the film in a flat plate furnace at a temperature of 180℃~220℃ for 1min~5min until the organic solvent evaporates and no moisture remains.

[0043] (6) Repeat steps (4) and (5) until the film thickness is 200nm~250nm.

[0044] (7) The thin film is crystallized in a rapid thermal annealing furnace (RTA) with a crystallization temperature of 600℃~700℃ and a crystallization time of 5min~10min to obtain a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio.

[0045] This invention proposes a (Mg, Al, Li) composite doping strategy that completely eliminates the dependence on weak intrinsic defects. First, by simultaneously and synergistically introducing donors (Al...) into the crystal lattice... 3+ ) and the recipient (Li + The element actively constructs a large number of adjacent donor-acceptor defect ion pairs within the crystal lattice. These artificially designed ion pairs strongly induce local symmetry breaking, thereby forming a large number of dipole moments. Ultimately, under electric field thermal polarization treatment, the electric dipole moments undergo directional reversal, exciting strong local ferroelectricity from the source, and thus generating an extremely strong self-polarized built-in electric field to achieve self-powering. While successfully obtaining a strong built-in electric field, the donor Al... 3+ The provided electrons were received by the host Li + In-situ compensation prevents the generation of a large number of free carriers in the thin film, maintaining the material in a high-resistivity insulating state and avoiding device performance degradation caused by dark current. At room temperature, Al... 3+ -Li +While ion pairs can be generated, the lack of a polar environment and the difficulty in overcoming high potential barriers prevent the directional reversal of the dipole moment, thus hindering strong local ferroelectricity and self-powered operation. Therefore, this invention introduces electric field polarization heat treatment technology. This technology increases the internal energy and thermodynamic activity of the system through thermal energy. Simultaneously, under polarized conditions, the electric dipole moment can achieve directional reversal and alignment along the polarization direction, thereby realizing strong local ferroelectricity. This allows for the construction of a self-powered solar-blind ultraviolet detector capable of efficiently generating and separating photogenerated carriers. Finally, Mg doping widens the light band, enabling the device to capture solar-blind ultraviolet light, ultimately fulfilling the core requirement of a self-powered solar-blind ultraviolet detector.

[0046] This invention also provides the application of the single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio in solar-blind detectors, comprising the following steps:

[0047] S1: A matching interdigitated electrode is deposited on the surface of a ZnO semiconductor thin film using DC magnetron sputtering to obtain a thin film device.

[0048] S2: The thin-film device is polarized at 180℃~200℃ and 70kV / cm~80kV / cm for 5h~8h, and then naturally cooled to room temperature in the electric field to obtain a self-powered solar-blind detector with a built-in electric field after polarization (e.g., Figure 1 (As shown).

[0049] The solar-blind detector provided by this invention has a light-to-dark ratio of up to 8031, a responsivity of up to 36.45 mA / W, and a transient response time as low as 11 ms.

[0050] The self-powered solar-blind ultraviolet detector constructed in this invention is based on an intrinsic silicon substrate. A single-phase oxide ferroelectric thin film is grown on the silicon substrate to form a semiconductor. After depositing Au interdigitated electrodes on the semiconductor surface, the detector is subjected to electric field polarization heat treatment to contain an internal electric field. Under UVC irradiation, the separation of photogenerated carriers is realized, and an electrical signal is formed and finally captured, thus realizing the detection function of solar-blind ultraviolet light.

[0051] The interdigitated electrodes used in this embodiment of the invention are made of Au.

[0052] This invention not only solves the problem of low response performance of traditional self-powered devices, but also provides a valuable engineering example of built-in electric field for developing a new solar-blind ultraviolet detection technology that combines ultra-low power consumption and extremely high sensitivity.

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0054] Comparative Example 1:

[0055] Step 1: Weigh 1.613g of zinc acetate, add ethylene glycol methyl ether to a final volume of 30mL under the action of 0.7mL ethanolamine, and stir the resulting solution at 55℃~65℃ for 1h~2h until a clear solution is formed.

[0056] Step 2: Add 0.676g of magnesium acetate, the dopant source, to the precursor solution obtained in Step 1, and stir at 55~65℃ for 0.5h~1h until a clear and uniform sol is formed. The concentration of the sol is controlled at 0.3mol / L~0.4mol / L.

[0057] Step 3: Aging the solution obtained in Step 2 at room temperature for more than 24 hours to form a colloid.

[0058] Step 4: Coat a thin film on the cleaned silicon substrate using the sol-gel method. First, spin coat at 2000 r / s for 5 seconds, and then spin coat at 4000 r / s for 15 seconds to ensure the uniformity of the film.

[0059] Step 5: After each spin-coating, the film needs to be placed on a 200°C flat plate oven for 3 minutes to evaporate the organic solvents and moisture.

[0060] Step 6: By repeating steps 4 and 5 multiple times and strictly controlling the number of spin coatings (6 to 7 times), a thin film with a thickness of 200nm-250nm can be obtained.

[0061] Step 7: The prepared thin film is crystallized in a rapid thermal annealing (RTA) furnace at a temperature of 600°C for 5 minutes to obtain a semiconductor thin film.

[0062] This comparative example also provides the application of the single-phase oxide ferroelectric semiconductor thin film in a solar-blind detector, including the following steps:

[0063] S1: A 0.0748 cm⁻¹ ZnO semiconductor thin film was deposited on the surface using DC magnetron sputtering. 2 Interdigitated electrodes.

[0064] S2: The prepared thin-film device was polarized at 180℃ and 70kV / cm~80kV / cm for 8 hours. Then, the applied electric field was maintained until the temperature dropped to room temperature, resulting in a polarized blind ultraviolet detector.

[0065] The photoelectric performance of the solar-blind detector obtained in this comparative example was tested, and its light-to-dark ratio was found to be 172 and its suppression ratio was 1.05.

[0066] Example 1:

[0067] Step 1: Weigh 1.567g of zinc acetate, add ethylene glycol methyl ether to a final volume of 30mL under the action of 0.7mL ethanolamine, and stir the resulting solution at 55℃~65℃ for 1~2h until a clear solution is formed.

[0068] Step 2: Add 0.676g magnesium acetate, 0.039g aluminum nitrate, and 0.007g lithium acetate to the precursor solution obtained in Step 1 in sequence, and stir at 55℃~65℃ for 0.5~1h until a clear and uniform sol is formed. The concentration of the sol is controlled at 0.3~0.4mol / L.

[0069] Step 3: Aging the solution obtained in Step 2 at room temperature for more than 24 hours to form a colloid.

[0070] Step 4: Coat a thin film on the cleaned silicon substrate using the sol-gel method. First, spin coat at 2000 r / s for 5 seconds, and then spin coat at 4000 r / s for 15 seconds to ensure the uniformity of the film.

[0071] Step 5: After each spin-coating, the film needs to be placed on a 200°C flat plate oven for 3 minutes to evaporate the organic solvents and moisture.

[0072] Step Six: By repeatedly performing Steps Four and Five, and strictly controlling the number of spin coatings (6-7 times), a thickness of 200nm-250nm and a chemical composition of Mg can be obtained. 0.3 Al 0.01 Li 0.01 Zn 0.68 ZnO thin film of O.

[0073] Step 7: The prepared thin film is crystallized in a rapid thermal annealing (RTA) furnace at a temperature of 600℃ for 5 minutes to obtain a single-phase oxide ferroelectric semiconductor thin film.

[0074] This embodiment also provides the application of the single-phase oxide ferroelectric semiconductor thin film in a solar-blind detector, including the following steps:

[0075] S1: A 0.0748 cm⁻¹ layer was deposited on the surface of a single-phase oxide ferroelectric semiconductor thin film using DC magnetron sputtering. 2 Interdigitated electrodes.

[0076] S2: The prepared thin film device is polarized at 180℃ and 70kV / cm~80kV / cm for 8 hours.

[0077] Subsequently, the applied electric field is maintained until the temperature drops to room temperature, resulting in a polarized, self-powered solar-blind detector with a built-in electric field.

[0078] The photoelectric performance of the solar blind detector obtained in this embodiment was tested, and its light-dark ratio was found to be 206 and its suppression ratio was 3.64.

[0079] Example 2:

[0080] Step 1: Weigh 1.475g of zinc acetate, add ethylene glycol methyl ether to a final volume of 30mL under the action of 0.7mL ethanolamine, and stir the resulting solution at 55℃~65℃ for 1h~2h until a clear solution is formed.

[0081] Step 2: Add 0.676g magnesium acetate, 0.118g aluminum nitrate, and 0.021g lithium acetate to the precursor solution obtained in Step 1 in sequence, and stir at 55℃~65℃ for 0.5h~1h until a clear and uniform sol is formed. The concentration of the sol is controlled at 0.3mol / L~0.4mol / L.

[0082] Step 3: Aging the solution obtained in Step 2 at room temperature for more than 24 hours to form a colloid.

[0083] Step 4: Coat a thin film on the cleaned silicon substrate using the sol-gel method. First, spin coat at 2000 r / s for 5 seconds, and then spin coat at 4000 r / s for 15 seconds to ensure the uniformity of the film.

[0084] Step 5: After each spin-coating, the film needs to be placed on a 200°C flat plate oven for 3 minutes to evaporate the organic solvents and moisture.

[0085] Step Six: By repeatedly performing Steps Four and Five, and strictly controlling the number of spin coatings (6-7 times), a thickness of 200nm-250nm and a chemical composition of Mg can be obtained. 0.3 Al 0.03 Li 0.03 Zn 0.64 ZnO thin film of O.

[0086] Step 7: The prepared thin film is crystallized in a rapid thermal annealing (RTA) furnace at a temperature of 600℃ for 5 minutes to obtain a single-phase oxide ferroelectric semiconductor thin film.

[0087] This embodiment also provides the application of the single-phase oxide ferroelectric semiconductor thin film in a solar-blind detector, including the following steps:

[0088] S1: A 0.0748 cm⁻¹ layer was deposited on the surface of a single-phase oxide ferroelectric semiconductor thin film using DC magnetron sputtering. 2 Interdigitated electrodes.

[0089] S2: The prepared thin film device is polarized at 180℃ and 70kV / cm~80kV / cm for 8 hours.

[0090] Subsequently, the applied electric field was maintained until the temperature dropped to room temperature, resulting in a polarized, self-powered solar-blind detector with a built-in electric field, named the MALZO solar-blind detector.

[0091] The photoelectric performance of the solar-blind detector obtained in this embodiment was tested, and its responsivity was found to be 36.45 mA / W, rise time 11.6 ms, fall time 11.8 ms, and specific detectivity 1.54 × 10⁻⁶. 11 Jones, with a light-to-dark ratio of 8031 ​​and a suppression ratio of 193.87.

[0092] Example 3:

[0093] Step 1: Weigh 1.383g of zinc acetate, add ethylene glycol methyl ether to a final volume of 30mL under the action of 0.7mL ethanolamine, and stir the resulting solution at 55℃~65℃ for 1h~2h until a clear solution is formed.

[0094] Step 2: Add 0.676g magnesium acetate, 0.197g aluminum nitrate, and 0.035g lithium acetate to the precursor solution obtained in Step 1 in sequence, and stir at 55℃~65℃ for 0.5h~1h until a clear and uniform sol is formed. The concentration of the sol is controlled at 0.3mol / L~0.4mol / L.

[0095] Step 3: Aging the solution obtained in Step 2 at room temperature for more than 24 hours to form a colloid.

[0096] Step 4: Coat a thin film on the cleaned silicon substrate using the sol-gel method. First, spin coat at 2000 r / s for 5 seconds, and then spin coat at 4000 r / s for 15 seconds to ensure the uniformity of the film.

[0097] Step 5: After each spin-coating, the film needs to be placed on a 200°C flat plate oven for 3 minutes to evaporate the organic solvents and moisture.

[0098] Step Six: By repeatedly performing Steps Four and Five, and strictly controlling the number of spin coatings (6-7 times), a thickness of 200nm-250nm and a chemical composition of Mg can be obtained. 0.3 Al 0.05 Li 0.05 Zn 0.6 ZnO thin film of O.

[0099] Step 7: The prepared thin film is crystallized in a rapid thermal annealing (RTA) furnace at a temperature of 600℃ for 5 minutes.

[0100] This embodiment also provides the application of the single-phase oxide ferroelectric semiconductor thin film in a solar-blind detector, including the following steps:

[0101] S1: A 0.0748 cm⁻¹ layer was deposited on the surface of a single-phase oxide ferroelectric semiconductor thin film using DC magnetron sputtering. 2 Interdigitated electrodes.

[0102] S2: The prepared thin film device is polarized at 180℃ and 70kV / cm~80kV / cm for 8 hours.

[0103] Subsequently, the applied electric field is maintained until the temperature drops to room temperature, resulting in a polarized, self-powered solar-blind detector with a built-in electric field.

[0104] The photoelectric performance of the solar blind detector obtained in this embodiment was tested, and its light-dark ratio was found to be 323 and its suppression ratio was 63.46.

[0105] Example 4:

[0106] Step 1: Weigh 1.291g of zinc acetate, add ethylene glycol methyl ether to a final volume of 30mL under the action of 0.7mL ethanolamine, and stir the resulting solution at 55℃~65℃ for 1h~2h until a clear solution is formed.

[0107] Step 2: Add 0.676g magnesium acetate, 0.276g aluminum nitrate, and 0.049g lithium acetate to the precursor solution obtained in Step 1 in sequence, and stir at 55℃~65℃ for 0.5h~1h until a clear and uniform sol is formed. The concentration of the sol is controlled at 0.3mol / L~0.4mol / L.

[0108] Step 3: Aging the solution obtained in Step 2 at room temperature for more than 24 hours to form a colloid.

[0109] Step 4: Coat a thin film on the cleaned silicon substrate using the sol-gel method. First, spin coat at 2000 r / s for 5 seconds, and then spin coat at 4000 r / s for 15 seconds to ensure the uniformity of the film.

[0110] Step 5: After each spin-coating, the film needs to be placed on a 200°C flat plate oven for 3 minutes to evaporate the organic solvents and moisture.

[0111] Step Six: By repeatedly performing Steps Four and Five, and strictly controlling the number of spin coatings (6-7 times), a thickness of 200nm-250nm and a chemical composition of Mg can be obtained. 0.3 Al 0.07 Li 0.07 Zn 0.56ZnO thin film of O.

[0112] Step 7: The prepared thin film is crystallized in a rapid thermal annealing (RTA) furnace at a temperature of 600℃ for 5 minutes.

[0113] This embodiment also provides the application of the single-phase oxide ferroelectric semiconductor thin film in a solar-blind detector, including the following steps:

[0114] S1: A 0.0748 cm⁻¹ layer was deposited on the surface of a single-phase oxide ferroelectric semiconductor thin film using DC magnetron sputtering. 2 Interdigitated electrodes.

[0115] S2: The prepared thin film device is polarized at 180℃ and 70kV / cm~80kV / cm for 8 hours.

[0116] Subsequently, the applied electric field is maintained until the temperature drops to room temperature, resulting in a polarized, self-powered solar-blind detector with a built-in electric field.

[0117] The photoelectric performance of the solar blind detector obtained in this embodiment was tested, and its light-dark ratio was found to be 301, its suppression ratio was 1185.02, but its responsivity was only 4.10 mA / W.

[0118] To investigate the crystallinity of the single-phase oxide ferroelectric semiconductor thin film provided by this invention, XRD tests were performed on the single-phase oxide ferroelectric semiconductor thin films prepared in different embodiments and comparative examples. The results are as follows: Figure 9 As shown. From Figure 9 As can be seen, with the increase of Al / Li co-doping content from x=0 to x=0.07, the diffraction peak intensities indicate that the local lattice distortion and increased defect concentration caused by co-doping reduce the crystallinity of the film. Among them, the sample with x=0.03 maintains obvious ZnO-based characteristic diffraction peaks while having a sufficient number of donor-acceptor defect ion pairs, achieving a good balance between structural stability and built-in electric field construction.

[0119] To further demonstrate the feasibility of self-powered systems, first-principles calculations were performed. The theoretical calculation results show that Al 3+ and Li + Entering the ZnO lattice, Al mainly exists in the form of replacing Zn sites. 3+ and Li + Ions directly form ion pairs, causing lattice distortion and generating localized ferroelectricity. Simultaneously, this invention simulates the electron density difference around the ion pairs and labels Al. 3+ and Li + The dipole moment formed by ions, along the dipole moment (P D The direction of ) from Li +Ions (negative charge centers) point towards Al 3+ Ions (positive charge centers) form a pattern of charge enrichment at one end and depletion at the other (e.g. Figure 2 As shown in the figure, this provides a theoretical basis for realizing self-polarized power supply of Al and Li-doped ZnO thin films.

[0120] Response speed is one of the core performance characteristics of a photodetector, and its quality significantly affects the detector's overall performance. To analyze the change in current with illumination, this invention utilizes an effective area of ​​0.0748 cm². 2 The incident light source is UVC band light with an intensity of 40mW / cm². 2 Under these conditions, switching light tests were conducted on solar-blind detectors prepared in different embodiments and comparative examples at five-second intervals. Analysis of the tests showed that, compared to the sluggishness of undoped and trace-doped detectors, x=0.03 was the optimal doping point when preparing the single-phase oxide ferroelectric semiconductor thin film in Example 2. At this point, the aluminum-lithium dipoles constructed the strongest local ferroelectric built-in electric field, achieving extremely rapid carrier separation, peak photocurrent, and a response time shortened to approximately 11 ms (e.g., ...). Figures 3-7 (As shown). Excessive doping can also lead to a sharp decline in photocurrent and response speed.

[0121] Other optical response parameters, such as responsivity and specific detectivity, also have a significant impact on device performance. Further analysis of the It curve reveals that Al... 3+ With Li + The co-doping concentration plays a decisive role in regulating the overall performance of this solar-blind ultraviolet detector. In a comparison of multi-dimensional performance indicators, the device performance reaches its optimal critical point when the doping concentration is precisely controlled at x=0.03. At this point, not only do core indicators such as light-dark ratio, specific detectivity, and responsivity all reach their optimal peak values, but when the doping concentration exceeds 0.03, excessive impurity atoms cause severe lattice distortion in the thin film and generate new lattice defects, leading to a degradation in various photoelectric properties.

[0122] Unlike other photodetectors, the solar-blind detector is designed specifically for detecting solar-blind ultraviolet light. Therefore, this invention uses light sources of different intensities for comparison. When the doping concentration x = 0.03, the UVA band light (25 mW / cm²) is compared. 2 ), under UVC light (40mW / cm) 2 Under irradiation, significant photogenerated carriers were generated and a strong response current (such as...) was detected. Figure 8As shown in the figure, calculations show that when x=0.03, the UVC / UVA suppression ratio reaches 194, greatly improving the detection function for the solar-blind ultraviolet band and shielding against interference from long-wavelength ultraviolet light. Therefore, the film composition ratio of the single-phase oxide ferroelectric semiconductor thin film is strictly defined as Mg 0.3 Al 0.03 Li 0.03 Zn 0.64 O is the optimal implementation scheme for solar-blind ultraviolet detection in this invention, which overcomes the slow response defect and achieves high signal-to-noise ratio and high suppression ratio.

[0123] To demonstrate the local ferroelectric properties of the semiconductor thin film provided by this invention, the hysteresis loop of the single-phase oxide ferroelectric semiconductor thin film prepared in Example 2 was tested under different applied electric fields. The results are as follows: Figure 10 As shown in the figure, the single-phase oxide ferroelectric semiconductor thin film with x=0.03 exhibits a closed hysteresis loop under different applied electric fields, indicating that the film has a significant local ferroelectric response. With increasing electric field strength, the polarization intensity gradually increases, and the hysteresis loop gradually becomes fuller. When the electric field reaches 714.3 kV / cm, the maximum polarization intensity is approximately 8.3 μC / cm. 2 This indicates that Al 3+ -Li + Defect dipoles align effectively under the influence of an electric field, forming strong local polarization and a built-in electric field within the thin film.

[0124] The performance comparison results of the solar blind detector prepared in Example 2 of this invention with the prior art are shown in Table 1.

[0125] Table 1. Performance overview of different solar-blind detectors;

[0126] ;

[0127] Note: Some data in the table is referenced from the following literature:

[0128] [1] A. Almaev, A. Tsymbalov, B. Kushnarev, V. Nikolaev, A. Pechnikov, M. Scheglov, and A. Chikiryaka, "Self-powered UVC detectors based on α-Ga2O3with enchanted speed performance," Journal of Semiconductors, vol. 45, no. 8, p. 082502, 2024.

[0129] [2] X. Zhou, L. Ye, L. Yuan, D. Zhang, H. Zhang, D. Pang, Y. Tang, H.Li, W. Li, and H. Zeng, "Mg-doped α-Ga2O3 Nanorods for the Construction ofPhotoelectrochemical-Type Self-Powered Solar Blind UV Photodetectors andUnderwater Imaging Application," Advanced Science, vol. 12, p. 2413074, 2025.

[0130] [3] D. Wang, C. Huang, X. Liu, H. Zhang, H. Yu, S. Fang, B. S. Ooi,Z. Mi, J.-H. He, and H. Sun, "Highly Uniform, Self-Assembled AlGaN Nanowiresfor Self-Powered Solar-Blind Photodetector with Fast-Response Speed and HighResponsivity," Advanced Optical Materials, vol. 9, p. 2000893, 2021.

[0131] [4] X. Zhou, S. Liu, J. Yang, J. Yang, F. Zhang, L. Yuan, R. Ma, J.Shi, Q. Xia, and M. Zhong, "Solar-blind ultraviolet photodetector derivedfrom direct carrier transition beyond the bandgap of CdPS3 single crystals,"Nano Research, vol. 17, no. 11, pp. 10042-10048, 2024.

[0132] [5] J. Chu, FM Wang, L. Yin, L. Lei, C. Yan, F. Wang, Y. Wen, Z. Wang, C. Jiang, L. Feng, J. Xiong, Y. Li, and J. He, "High-PerformanceUltraviolet Photodetector Based on a Few-Layered 2D NiPS3 Nanosheet," Advanced Functional Materials, vol. 27, p. 1701342, 2017.

[0133] As shown in the table, this invention does not simply pursue the highest value for any single indicator, but rather simultaneously considers responsivity, response speed, specific detectivity, light-dark ratio, and suppression ratio under zero applied bias conditions, demonstrating good overall self-powered solar-blind ultraviolet detection performance. This result indicates that Mg, Al, and Li synergistic co-doped ZnO-based thin films can effectively construct a built-in electric field and promote photogenerated carrier separation, offering advantages such as low power consumption, simplified structure, and selective solar-blind ultraviolet detection.

Claims

1. A single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio, characterized in that, It includes a silicon substrate and an active absorber layer grown on the silicon substrate. The active absorber layer is a ZnO thin film co-doped with Mg, Al, and Li, and its general chemical formula is Mg. 0.3 Al x Li x Zn 0.7-2x O, where x = 0.01~0.07; the thickness of the ZnO film is 200nm~250nm.

2. The single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio according to claim 1, characterized in that, In the ZnO thin film, Al 3+ As a benefactor, Li + As acceptors, the two form adjacent defect ion pairs at the Zn site, inducing local symmetry breaking and forming an electric dipole moment. Subsequently, electric field heat treatment causes the ion pairs to flip in an oriented manner, forming a local self-built electric field.

3. The method for preparing a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio as described in claim 1, characterized in that, Includes the following steps: Step 1: Dissolve zinc acetate in ethylene glycol methyl ether under the action of a complexing agent, and stir the resulting solution at a constant temperature until a clear precursor solution is formed; Step 2: Under water bath heating and stirring conditions, the dopant source, lithium acetate and aluminum nitrate are added to the precursor solution in sequence to form a clear and uniform sol; Step 3: Let the sol age at room temperature for more than 24 hours to form a colloid; Step 4: Coat a thin film on a cleaned silicon substrate using the sol-gel method. First, spin coat the colloid at a speed of 1500r / s to 2000r / s for 5s to 10s, and then spin coat at a speed of 3500r / s to 4000r / s for 10s to 15s. Step 5: Pyrolyze the spin-coated product to evaporate the organic solvents and moisture; Step Six: Repeat Steps Four and Five until the ZnO film reaches the target thickness; Step 7: Crystallize the ZnO thin film to obtain a single-phase oxide ferroelectric semiconductor thin film.

4. The method for preparing a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio according to claim 3, characterized in that, In step one, the stirring temperature is 55℃~65℃, and the stirring time is 1h~2h.

5. The method for preparing a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio according to claim 3, characterized in that, In step two, after each reagent is added, stir for 0.5 h to 1 h, and then add the next reagent; The water bath heating temperature is 55℃~65℃; the sol concentration is 0.3mol / L~0.4mol / L.

6. The method for preparing a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio according to claim 3, characterized in that, In step five, pyrolysis is performed at 180℃~220℃ for 1 min~5 min.

7. The method for preparing a single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio according to claim 3, characterized in that, In step seven, the crystallization temperature is 600℃~700℃, and the crystallization time is 5min~10min.

8. The application of the single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio as described in claim 1, characterized in that, The application of the single-phase oxide ferroelectric semiconductor thin film in solar-blind detectors includes the following steps: S1: Interdigitated electrodes are deposited on the surface of a ZnO semiconductor thin film by DC magnetron sputtering to obtain a thin film device; S2: The prepared thin film device is subjected to electric field polarization treatment under a certain temperature and electric field, and then naturally cooled to room temperature in the electric field to obtain a self-powered solar blind detector with a built-in electric field after polarization.

9. The application of the single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio according to claim 8, characterized in that, In S1, the area of ​​the interdigitated electrode is matched with the area of ​​the ZnO semiconductor thin film; In S2, the polarization temperature is 180℃-200℃, the polarization time is 5h~8h, and the polarization electric field strength is 70kV / cm~80kV / cm.

10. The application of the single-phase oxide ferroelectric semiconductor thin film with low dark current and high UVC / UVA ratio according to claim 8, characterized in that, The solar-blind detector has a maximum light-to-dark ratio of 8031, a maximum responsivity of 36.45 mA / W, and a minimum transient response time of 11 ms.

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