Laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector and preparation method thereof

Abstract

The application relates to the field of semiconductor photoelectric technology, in particular to a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector and a preparation method. The method comprises the following steps: cleaning a substrate; taking a ZnO-MgO composite target as a sputtering source, and adopting a radio frequency magnetron sputtering technology to deposit a MgZnO film on the pretreated substrate; building a femtosecond laser processing system, doubling the original laser emitted by a femtosecond laser through a frequency doubling crystal, adjusting the laser pulse energy through a polarization adjusting assembly, focusing the laser beam on the surface of the MgZnO film on a displacement platform through an objective lens, obtaining MgZnO nanostripe through scanning processing, and performing surface cleaning; and adopting a vacuum evaporation coating technology to evaporate a metal electrode layer on the surface of the MgZnO nanostripe. The method has the advantages that the operation is simple and reliable, the nanostructure self-assembly and morphology regulation can be accurately realized, the Mg element controllable doping can be realized by regulating the target component, and the process is efficient, fast and controllable.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic technology, and in particular to a laser-induced oxygen-zinc-magnesium nanostripes solar-blind ultraviolet photodetector and its preparation method. Background Technology

[0002] Solar-blind ultraviolet (UV) detection, particularly in the 240nm-280nm band, offers the advantage of being unaffected by solar radiation signals. It holds significant promise for applications in UV early warning, secure communications, missile tracking, power grid security monitoring, and global environmental monitoring, making it a crucial core technology related to national security and of significant strategic importance. Solar-blind UV photodetectors are the core of UV detection technology, and practical devices typically possess characteristics such as high sensitivity, high signal-to-noise ratio, high response speed, and high spectral selectivity. With the continuous advancement of research into semiconductor materials and device fabrication processes, the emergence of wide-bandgap semiconductor materials has provided new impetus for the research and application of high-performance UV detectors. Unlike the previously commonly used silicon-based materials, wide-bandgap materials exhibit excellent frequency selectivity, effectively shielding visible and infrared light, thus avoiding the need for filtering devices. Among these, various metal-oxide-semiconductor (MODS) materials, due to their stable properties, low cost, diverse fabrication processes, and excellent electronic and optical properties, have been widely used as photosensitive materials for UV detectors.

[0003] Mg x Zn 1-x Oxide (MgZnO) is an oxide semiconductor material with a wide bandgap modulation range, possessing excellent properties such as strong radiation resistance, low defect density, environmental friendliness, and chemical stability. Furthermore, by changing the Mg doping amount, its bandgap can be significantly adjusted from 3.37 eV to 7.8 eV, covering a continuously tunable bandgap range across the entire solar-blind ultraviolet band, showing significant application potential in the field of solar-blind ultraviolet detection. After years of development, solar-blind ultraviolet photodetectors based on MgZnO materials have achieved a series of research results. In particular, one-dimensional MgZnO nanowires, as oriented one-dimensional nanostructures, possess high specific surface area and high electron mobility, enabling efficient transport and collection of photogenerated carriers, effectively improving the photoelectric performance of MgZnO solar-blind ultraviolet photodetectors.

[0004] However, the current methods for preparing MgZnO nanowires still have the following problems: (1) The preparation process of MgZnO nanowires and their solar-blind detectors is complex: The preparation methods of MgZnO nanowires are mainly concentrated in chemical vapor deposition, electrochemical deposition, hydrothermal synthesis, etc. These methods have problems such as complex processes, the need to introduce metal catalysts, and difficulty in controlling product uniformity. (2) It is difficult to control the doping of Mg element in MgZnO nanowires: Mg x Zn 1-xO materials can achieve solar-blind band detection under high Mg composition (x>0.5) conditions, but based on the existing MgZnO nanowire preparation method, it is still difficult to effectively dope ZnO with Mg, especially the controllable doping with high Mg composition is difficult to achieve, which makes it difficult for the detection range of the corresponding detector to cover the entire solar-blind ultraviolet band at present.

[0005] Therefore, developing a simple, catalyst-free method for preparing MgZnO nanowires with precise and controllable high Mg content is crucial for overcoming existing technological bottlenecks and enabling MgZnO-based solar-blind ultraviolet photodetectors to achieve full-band detection and practical application. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a laser-induced oxygen-zinc-magnesium nanostripes solar-blind ultraviolet photodetector and its preparation method.

[0007] The primary objective of this invention is to provide a method for fabricating a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector, specifically comprising the following steps:

[0008] S1. Clean the substrate and dry it with nitrogen gas;

[0009] S2. Using a ZnO-MgO composite target as the sputtering source, MgZnO thin films are deposited on the pretreated substrate using radio frequency magnetron sputtering technology;

[0010] S3. Construct a femtosecond laser processing system, and set up a femtosecond laser, a frequency doubling crystal, a polarization adjustment component, an objective lens, and a displacement platform in sequence along the optical path; double the original laser emitted by the femtosecond laser through the frequency doubling crystal, and then adjust the laser pulse energy through the polarization adjustment component. The objective lens focuses the laser beam onto the surface of the MgZnO thin film on the displacement platform, and obtains MgZnO nano-stripes through scanning processing.

[0011] S4. Clean the surface of the sample with MgZnO nanostripes; use vacuum evaporation coating technology to deposit a metal electrode layer on the surface of the MgZnO nanostripes to obtain a laser-induced oxygen zinc magnesium nanostripe solar-blind ultraviolet photodetector.

[0012] Preferably, in the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is (40~60):(60~40);

[0013] The process parameters for the radio frequency magnetron sputtering include: a vacuum level not exceeding 5.0 × 10⁻⁶. -4 The working gas is argon and oxygen, the sputtering pressure is 2~4 Pa, the sputtering power is 120~180 W, and the growth time is 2~4 h.

[0014] Preferably, in the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is 50:50;

[0015] During the radio frequency magnetron sputtering process, the flow rate ratio of argon to oxygen is 60:3 sccm, and the substrate temperature is 350~450℃.

[0016] Preferably, in step S3, the frequency doubling crystal is a barium borate crystal; the polarization adjustment component includes a first half-wave plate, a polarizing beam splitter prism, and a second half-wave plate arranged sequentially; the parameters of the scanning process include: laser single pulse energy of 30~50μJ and scanning speed of 0.8~1.6mm / s.

[0017] Preferably, the pulse duration of the femtosecond laser is 200~350 fs, and the repetition frequency is 5~15 kHz;

[0018] The objective lens has a magnification of not less than 50× and a numerical aperture of not less than 0.8.

[0019] Preferably, in step S4, during the vacuum evaporation coating process, the material is first preheated with a current of 15-25 mA for 8-12 minutes, then grown with a current of 45-55 mA for 8-12 minutes, with a vacuum degree not exceeding 8.0 × 10⁻⁶. -4 Pa.

[0020] Preferably, in step S4, the surface cleaning method is nitrogen purging; the metal electrode layer is an Al electrode layer.

[0021] The second objective of this invention is to provide a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector, which is prepared using the aforementioned method for preparing a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector, comprising, from bottom to top, a substrate, a MgZnO nanostripe layer, and a metal electrode layer.

[0022] Preferably, the detector's responsivity peak is located at 270~280nm, and the response cutoff edge is located at 290~310nm.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0024] (1) The preparation method of the present invention is simple and reliable, and can realize the self-assembly and precise control of the morphology of nanostructures, thus reducing the technical threshold for nanostructure preparation.

[0025] (2) By adjusting the composition of the ZnO-MgO composite target, the Mg element in the MgZnO nano stripes can be controlled, providing a flexible solution for the preparation of materials to meet different solar-blind ultraviolet detection requirements;

[0026] (3) The preparation process does not require the introduction of external doping sources, effectively avoiding the introduction of contaminants and ensuring the stability of the optoelectronic performance of the device;

[0027] (4) The overall preparation process is efficient and fast, highly controllable, suitable for large-scale production and application, and has good prospects for industrial transformation. Attached Figure Description

[0028] Fig. 1 This is a flowchart of the fabrication method of a laser-induced oxygen-zinc-magnesium nanostripes solar-blind ultraviolet photodetector according to an embodiment of the present invention.

[0029] Fig. 2 This is a schematic diagram of the optical path for femtosecond laser processing according to an embodiment of the present invention.

[0030] Figure label:

[0031] 1. Femtosecond laser;

[0032] 2. Barium metaborate crystals;

[0033] 3. First half-wave plate;

[0034] 4. Polarizing beam splitter prism;

[0035] 5. Second half-wave plate;

[0036] 6. Objective lens;

[0037] 7. High-precision displacement platform. Detailed Implementation

[0038] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0040] This invention provides a method for preparing a laser-induced oxygen-zinc-magnesium nanostripes solar-blind ultraviolet photodetector, specifically including the following steps:

[0041] S1. Clean the substrate and dry it with nitrogen gas;

[0042] The cleaning was performed using ultrasonic cleaning. The substrate was ultrasonically cleaned sequentially with acetone, anhydrous ethanol and deionized water, with each ultrasonic cleaning session lasting 10 to 20 minutes.

[0043] The substrate is a quartz substrate, a sapphire substrate, or a silicon substrate.

[0044] S2. Preparation of MgZnO thin film by magnetron sputtering: Using a composite target of ZnO and MgO as the sputtering source, MgZnO thin film is deposited on the pretreated substrate by radio frequency magnetron sputtering technology;

[0045] Specifically, in the composite target material of ZnO and MgO, the atomic ratio of ZnO to MgO is (40~60):(60~40);

[0046] The process parameters for RF magnetron sputtering include: a base vacuum level not exceeding 5.0 × 10⁻⁶. -4 The working gas is argon and oxygen, the sputtering pressure is 2~4 Pa, the sputtering power is 120~180 W, the substrate temperature is 350~450℃, and the growth time is 2~4 h.

[0047] S3. Femtosecond laser processing to prepare MgZnO nanostripes: A femtosecond laser processing system is constructed, which includes a femtosecond laser, a frequency doubling crystal, a polarization adjustment component, an objective lens, and a displacement platform along the optical path. The original laser emitted by the femtosecond laser is frequency doubled by the frequency doubling crystal. After the laser pulse energy is adjusted by the polarization adjustment component, the laser beam is focused onto the surface of the MgZnO thin film on the displacement platform by the objective lens. MgZnO nanostripes are obtained by scanning.

[0048] Specifically, the frequency doubling crystal is a barium borate crystal; the polarization adjustment component includes a first half-wave plate, a polarizing beam splitter prism, and a second half-wave plate arranged sequentially; the scanning processing parameters include: laser single pulse energy of 30~50μJ, scanning speed of 0.8~1.6mm / s; and the pulse duration of the femtosecond laser of 200~350fs and repetition frequency of 5~15kHz.

[0049] In some embodiments, the original laser wavelength of the femtosecond laser is 1030 nm, the pulse duration is 280 fs, the repetition frequency is 10 kHz, and the laser wavelength after frequency doubling is 515 nm; the magnification of the objective lens is not less than 50×, the numerical aperture is not less than 0.8, the laser single pulse energy is 40 μJ, and the scanning speed is V = 1.2 mm / s.

[0050] S4. Evaporated electrode: After cleaning the surface of the sample with MgZnO nanostripes, a metal electrode layer is deposited on the surface of the MgZnO nanostripes using vacuum evaporation coating technology to obtain a laser-induced oxygen zinc magnesium nanostripes solar-blind ultraviolet photodetector.

[0051] Specifically, the surface cleaning method is nitrogen purging;

[0052] The process parameters for vacuum evaporation coating include: a base vacuum level not exceeding 8.0 × 10⁻⁶.-4 Pa, the metal electrode layer is an Al electrode layer. The evaporation process is first preheated with a current of 15~25mA for 8~12min, and then grown with a current of 45~55mA for 8~12min.

[0053] In some embodiments, the evaporation process is first preheated with a current of 20mA for 10 minutes, and then grown with a current of 50mA for 10 minutes.

[0054] Example 1

[0055] See Figs. 1-2 This embodiment provides a method for fabricating a laser-induced oxygen-zinc-magnesium nanostripes solar-blind ultraviolet photodetector, specifically including the following steps:

[0056] S1. Substrate pretreatment: Quartz substrate was selected as the deposition substrate. The substrate was ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water. Each ultrasonic cleaning time was 15 minutes to thoroughly remove oil and impurities from the substrate surface. After cleaning, the substrate was dried in a nitrogen atmosphere and set aside for later use.

[0057] S2. Magnetron Sputtering: Radio frequency magnetron sputtering technology is employed, using a ZnO:MgO mixed target of 50:50 at% as the sputtering source. The pretreated substrate and the mixed target are loaded together into the vacuum chamber of the radio frequency magnetron sputtering equipment. The vacuum unit is started to evacuate the base vacuum of the sputtering equipment's vacuum chamber to 5.0 × 10⁻⁶. -4 Pa; then argon and oxygen were introduced into the vacuum chamber as working gases, and the Ar:O2 flow ratio was precisely controlled at 60:3 sccm, and the equipment was adjusted to stabilize the sputtering pressure at 3 Pa; the sputtering power of the RF magnetron sputtering equipment was set to 150 W, the substrate tray rotation speed to 5 r / min, and the substrate temperature to 400 °C; the sputtering program was started, and the parameters were maintained for continuous growth for 3 h to complete the thin film deposition process and obtain Mg 0.52 Zn 0.48 O thin film.

[0058] S3. Femtosecond laser processing to prepare MgZnO nanostripes: A femtosecond laser processing system was built, and along the optical path were arranged a femtosecond laser 1, a barium borate crystal 2 (BBO), a first half-wave plate 3 (515nm), a polarizing beam splitter prism 4, a second half-wave plate 5 (515nm), an objective lens 6, and a high-precision displacement platform 7.

[0059] The barium metaborate crystal 2 doubles the frequency of the original laser emitted by the femtosecond laser 1 to a 515nm laser. The laser pulse energy is adjusted using a first half-wave plate 3, a polarizing beam splitter prism 4, and a second half-wave plate 5. Specifically, the polarization direction of the laser is changed by rotating the first half-wave plate 3, causing the laser to split into reflected and transmitted light after entering the polarizing beam splitter prism 4, thus initially adjusting the laser energy ratio. Then, the polarization direction of the transmitted laser is finely adjusted by rotating the second half-wave plate 5, achieving precise control of the laser pulse energy in conjunction with the polarizing beam splitter prism 4, ensuring stable output laser energy that meets processing requirements. The objective lens 6 focuses the energy-adjusted 515nm laser beam onto the Mg... 0.52 Zn 0.48 O thin film surface; Mg 0.52 Zn 0.48 The O-film is fixed on a high-precision displacement platform 7. The movement parameters of the high-precision displacement platform 7 are set to match the laser processing parameters. The laser processing program is started and linked with the displacement platform. 0.52 Zn 0.48 O thin film surface scanning processing was used to prepare MgZnO nano stripes with uniform morphology and consistent size.

[0060] Femtosecond laser 1 uses an all-solid-state femtosecond laser with a wavelength of 1030nm, a pulse duration of 280fs, and a repetition frequency of 10kHz as the laser source.

[0061] Objective lens 6 is selected with a magnification of 100× and a numerical aperture NA of 0.9;

[0062] The laser processing parameters and movement parameters are as follows: laser single pulse energy is 40μJ, and scanning speed V=1.2mm / s.

[0063] S4. Electrode Deposition for Detector Fabrication: After processing, the sample with MgZnO nanostripes undergoes surface cleaning, using nitrogen purging to remove minute debris generated during processing. The sample is then transferred to a vacuum evaporation coating apparatus to deposit an Al electrode layer onto the MgZnO nanostripe surface. Before deposition, the base vacuum of the vacuum evaporation apparatus is evaporated to 8.0 × 10⁻⁶. -4 Pa, set the evaporation current to 20mA, preheat the Al evaporation source for 10min to remove trace impurities and moisture from the Al raw material; after the metallic Al reaches the molten state and evaporates stably, increase the current to 50mA and maintain this parameter for 10min to complete the uniform evaporation of the Al electrode layer, and finally obtain the laser-induced oxygen zinc magnesium nanostriped solar-blind ultraviolet photodetector.

[0064] The performance of the MgZnO nanostripe solar-blind ultraviolet photodetector prepared in this embodiment was tested. The results showed that the responsivity peak of the detector was located at 275 nm and the response cutoff edge was located at 300 nm, which showed that the detector had good solar-blind ultraviolet band detection capability.

[0065] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0066] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for fabricating a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector, characterized in that: Specifically, the steps include the following: S1. Clean the substrate and dry it with nitrogen gas; S2. Using a ZnO-MgO composite target as the sputtering source, MgZnO thin films are deposited on the pretreated substrate using radio frequency magnetron sputtering technology; S3. Construct a femtosecond laser processing system, sequentially arranging a femtosecond laser, a frequency-doubling crystal, a polarization adjustment component, an objective lens, and a displacement platform along the optical path. The original laser emitted by the femtosecond laser is frequency-doubled by the frequency-doubling crystal, and the laser pulse energy is then adjusted by the polarization adjustment component. The objective lens focuses the laser beam onto the surface of a MgZnO thin film on the displacement platform, and MgZnO nanofibers are obtained through scanning processing. The frequency-doubling crystal is a barium metaborate crystal. The polarization adjustment component includes a first half-wave plate, a polarizing beam-splitting prism, and a second half-wave plate arranged sequentially. The scanning processing parameters include: a single laser pulse energy of 30~50μJ, a scanning speed of 0.8~1.6mm / s, a pulse duration of 200~350fs, and a repetition frequency of 5~15kHz for the femtosecond laser. The objective lens has a magnification of not less than 50× and a numerical aperture of not less than 0.

8. S4. Clean the surface of the sample with MgZnO nanostripes; use vacuum evaporation coating technology to deposit a metal electrode layer on the surface of the MgZnO nanostripes to obtain a laser-induced oxygen zinc magnesium nanostripe solar-blind ultraviolet photodetector.

2. The method for preparing a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector according to claim 1, characterized in that: In the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is (40~60):(60~40); The process parameters for the radio frequency magnetron sputtering include: a vacuum level not exceeding 5.0 × 10⁻⁶. -4 The working gas is argon and oxygen, the sputtering pressure is 2~4 Pa, the sputtering power is 120~180 W, and the growth time is 2~4 h.

3. The method for preparing a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector according to claim 2, characterized in that: In the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is 50:50; During the radio frequency magnetron sputtering process, the flow rate ratio of argon to oxygen is 60:3 sccm, and the substrate temperature is 350~450℃.

4. The method for preparing a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector according to claim 1, characterized in that: In step S4, during the vacuum evaporation coating process, the material is first preheated with a current of 15-25 mA for 8-12 minutes, then grown with a current of 45-55 mA for 8-12 minutes, with a vacuum degree not exceeding 8.0 × 10⁻⁶. -4 Pa.

5. The method for preparing a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector according to claim 4, characterized in that: In step S4, the surface cleaning method is nitrogen purging; the metal electrode layer is an Al electrode layer.

6. A laser-induced oxygen-zinc-magnesium nanostripes solar-blind ultraviolet photodetector, prepared using the method described in claim 1, characterized in that: From bottom to top, it includes a substrate, a MgZnO nanostripe layer, and a metal electrode layer.

7. The laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector according to claim 6, characterized in that: The detector's responsivity peak is located at 270~280nm, and the response cutoff edge is located at 290~310nm.

Images