Laser-induced oxygen-zinc-magnesium nano stripe solar-blind ultraviolet photoelectric detector and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor photoelectricity, in particular to a laser-induced oxygen-zinc-magnesium nano stripe solar-blind ultraviolet photoelectric detector and a preparation method thereof. The method comprises the steps of cleaning a substrate; taking a ZnO-MgO composite target material as a sputtering source, and depositing an MgZnO thin film on the pretreated substrate by adopting a radio frequency magnetron sputtering technology; a femtosecond laser processing system is built, original laser emitted by a femtosecond laser device is subjected to frequency doubling through a frequency doubling crystal, laser pulse energy is adjusted through a polarization adjusting assembly, laser beams are focused on the surface of the MgZnO thin film on a displacement platform through an objective lens, MgZnO nano stripes are obtained through scanning processing, and surface cleaning is carried out; and evaporating a metal electrode layer on the surface of the MgZnO nano stripe by adopting a vacuum evaporation coating technology. The method has the advantages that the operation is simple, convenient and reliable, and self-assembly and form regulation and control of the nanostructure can be accurately realized; controllable doping of the Mg element can be realized by regulating and controlling the components of the target material; the process is efficient and fast, and the controllability is high.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of semiconductor photoelectricity, and in particular to a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector and a preparation method thereof. BACKGROUND

[0002] Solar-blind band (240 nm-280 nm) ultraviolet detection has the advantage of not being interfered by solar radiation signals, and has important application prospects in the fields of ultraviolet early warning, secure communication, missile tracking, power grid safety monitoring and global environmental monitoring, and is one of the key core technologies related to national security and has important strategic significance. A solar-blind ultraviolet photodetector is the core of ultraviolet detection technology, and a practical device should have the characteristics of high sensitivity, high signal-to-noise ratio, high response speed and high spectral selectivity. With the continuous deepening of research on semiconductor materials and device preparation processes, the emergence of wide-bandgap semiconductor materials provides new impetus for the research and application of high-performance ultraviolet detectors. Unlike the silicon-based materials commonly used in the early days, wide-bandgap materials have excellent band selectivity and can effectively shield visible light and infrared light, thereby avoiding the introduction of filtering equipment; among them, a variety of metal oxide semiconductor materials have been widely used as photosensitive materials for ultraviolet detectors due to their stable properties, low cost, diversified preparation processes and excellent electronic and optical properties.

[0003] Mg x Zn 1-x As an oxide semiconductor material with a wide bandgap modulation range, MgZnO has the advantages of strong radiation resistance, low defect density, environmental friendliness and stable chemical properties; and by changing the amount of Mg doping, the bandgap width can be significantly adjusted from 3.37 eV to 7.8 eV, covering the entire solar-blind ultraviolet band with a continuously adjustable bandgap range, which has important application prospects in the field of solar-blind ultraviolet detection. After years of development, a series of research results have been achieved in solar-blind ultraviolet photodetectors based on MgZnO materials. In particular, one-dimensional MgZnO nanowires, as directional one-dimensional nanostructures, have high specific surface area and high electron mobility, which can realize efficient transport and collection of photo-generated carriers and effectively improve the photoelectric performance of MgZnO solar-blind ultraviolet photodetectors.

[0004] However, the current preparation method of MgZnO nanowires still has the following problems: (1) The preparation process of MgZnO nanowires and solar-blind detectors is complex: the preparation method of MgZnO nanowires mainly focuses on chemical vapor deposition, electrochemical deposition, hydrothermal synthesis, etc., which has the problems of complex process, the need to introduce metal catalysts, and difficult control of product uniformity, etc. (2) Difficult controllable doping of Mg element in MgZnO nanowires: Mg x Zn 1-xThe O material can realize the detection of the solar blind wave band under the condition of high Mg component (x>0.5), but it is still difficult to effectively dope Mg to ZnO based on the existing preparation method of MgZnO nanowire, especially the controllable doping of high Mg component, which makes it difficult for the corresponding detector to cover the entire solar blind ultraviolet wave band.

[0005] Therefore, developing a preparation method of MgZnO nanowire which is simple in process, does not need metal catalyst and can realize precise and controllable doping of high Mg component, becomes the key to break through the bottleneck of the prior art and promote the realization of full wave band detection and practicalization of the MgZnO-based solar blind ultraviolet photodetector. SUMMARY

[0006] The application provides a laser-induced oxygen-zinc-magnesium nanostripe solar blind ultraviolet photodetector and a preparation method.

[0007] The first object of the application is to provide a preparation method of a laser-induced oxygen-zinc-magnesium nanostripe solar blind ultraviolet photodetector, which specifically comprises the following steps: S1. cleaning a substrate and blowing dry with nitrogen; S2. using a ZnO-MgO composite target as a sputtering source to deposit a MgZnO film on the pretreated substrate by radio frequency magnetron sputtering technology; S3. building a femtosecond laser processing system, and sequentially arranging a femtosecond laser, a frequency doubling crystal, a polarization adjusting assembly, an objective lens and a displacement platform along the light path; the original laser emitted by the femtosecond laser is frequency doubled through the frequency doubling crystal, and then the laser pulse energy is adjusted through the polarization adjusting assembly, and then the laser beam is focused on the surface of the MgZnO film on the displacement platform through the objective lens, so that the MgZnO nanostripe is obtained through scanning processing; S4. cleaning the sample with the MgZnO nanostripe; and using vacuum evaporation film technology to evaporate a metal electrode layer on the surface of the MgZnO nanostripe, so as to obtain the laser-induced oxygen-zinc-magnesium nanostripe solar blind ultraviolet photodetector.

[0008] Preferably, in the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is (40-60):(60-40); The process parameters of the radio frequency magnetron sputtering include: the vacuum degree is not higher than 5.0*10 -4 Pa, 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.

[0009] Preferably, in the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is 50:50; In the radio frequency magnetron sputtering process, the flow ratio of argon and oxygen is 60:3 sccm, and the substrate temperature is 350-450 DEG C.

[0010] Preferably, in step S3, the frequency-doubling crystal is a barium metaborate crystal; the polarization adjustment component comprises a first half-wave plate, a polarization beam splitting prism and a second half-wave plate arranged in sequence; and the scanning processing parameters comprise: a laser single-pulse energy of 30-50 muJ and a scanning speed of 0.8-1.6 mm / s.

[0011] Preferably, the pulse duration of the femtosecond laser is 200-350 fs, and the repetition frequency is 5-15 kHz. The magnification of the objective lens is not less than 50x, and the numerical aperture is not less than 0.8.

[0012] Preferably, in step S4, in the vacuum evaporation plating process, the substrate is preheated at a current of 15-25 mA for 8-12 min, and then grown at a current of 45-55 mA for 8-12 min, and the vacuum degree is not higher than 8.0*10 -4 Pa.

[0013] Preferably, in step S4, the surface cleaning method is nitrogen blowing; and the metal electrode layer is an Al electrode layer.

[0014] The second object of the application is to provide a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector, which is prepared by the preparation method of the laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector, and comprises, from bottom to top, a substrate, a MgZnO nanostripe layer and a metal electrode layer.

[0015] Preferably, the response peak of the photodetector is located at 270-280 nm, and the response cutoff edge is located at 290-310 nm.

[0016] Compared with the prior art, the application can achieve the following beneficial effects: (1) The preparation method is simple and reliable, can realize self-assembly of the nanostructure and precise control of the morphology, and reduces the technical threshold of nanostructure preparation; (2) Controllable doping of Mg elements in the MgZnO nanostripe can be realized by adjusting the component of the ZnO-MgO composite target, which provides a flexible scheme for material preparation to adapt to different solar-blind ultraviolet detection requirements; (3) The preparation process does not need to introduce an external doping source, effectively avoids the intervention of pollutants, and guarantees the stability of the photoelectric performance of the device; (4) The overall preparation process is efficient, fast and controllable, is suitable for large-scale production and application, and has good industrial conversion prospects. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 is a preparation method flow chart of a laser-induced oxygen-zinc-magnesium nanostripe solar blind ultraviolet photodetector according to an embodiment of the present application.

[0018] Fig. 2 is a femtosecond laser processing optical path schematic diagram according to an embodiment of the present application.

[0019] Reference signs: 1. femtosecond laser; 2. barium metaborate crystal; 3. first half-wave plate; 4. polarization beam splitting prism; 5. second half-wave plate; 6. objective lens; 7. high-precision displacement platform. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference signs. In the case of the same reference signs, their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0021] In order to make the objectives, technical solutions and advantages of the present application more clear, the present application 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 only used to explain the present application, and do not constitute a limitation on the present application.

[0022] The present application provides a preparation method of a laser-induced oxygen-zinc-magnesium nanostripe solar blind ultraviolet photodetector, specifically comprising the following steps: S1. cleaning the substrate and blowing dry with nitrogen; The cleaning is ultrasonic cleaning, and the substrate is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, and the ultrasonic cleaning time is 10-20 min each time; The substrate is a quartz substrate, a sapphire substrate or a silicon substrate.

[0023] S2. magnetron sputtering preparation of MgZnO film: using a composite target of ZnO and MgO as a sputtering source, depositing a MgZnO film on the pretreated substrate by using a radio frequency magnetron sputtering technology; Specifically, in the composite target of ZnO and MgO, the atomic ratio of ZnO to MgO is (40-60):(60-40); The process parameters of the radio frequency magnetron sputtering include: a base vacuum degree of not higher than 5.0×10 -4 Pa, 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.

[0024] 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. 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. 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.

[0025] 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. Specifically, the surface cleaning method is nitrogen purging; 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. 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.

[0026] Example 1 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: 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.

[0027] 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.

[0028] 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. 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. 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. Objective lens 6 is selected with a magnification of 100× and a numerical aperture NA of 0.9; The laser processing parameters and movement parameters are as follows: laser single pulse energy is 40μJ, and scanning speed V=1.2mm / s.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 comprising the following steps: S1. cleaning the substrate and drying it with nitrogen; S2. depositing a MgZnO film on the pretreated substrate by using a radio frequency magnetron sputtering technology with a ZnO-MgO composite target as a sputtering source; S3. setting up a femtosecond laser processing system, sequentially setting a femtosecond laser, a frequency doubling crystal, a polarization adjusting assembly, an objective lens and a displacement platform along the light path direction; the original laser emitted by the femtosecond laser is frequency-doubled by the frequency doubling crystal, and then the laser pulse energy is adjusted by the polarization adjusting assembly, and then the laser beam is focused on the surface of the MgZnO film on the displacement platform by the objective lens, and the MgZnO nanostripe is obtained by scanning processing; S4. cleaning the sample with MgZnO nanostripe; using a vacuum evaporation film technology, evaporating a metal electrode layer on the surface of the MgZnO nanostripe to obtain a laser-induced ZnO-Mg nanostripe solar blind ultraviolet photodetector.

2. The method for preparing a laser-induced ZnO-MgO nanostripe solar blind UV photodetector according to claim 1, wherein: In the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is (40-60):(60-40); The process parameters of the radio frequency magnetron sputtering include: vacuum degree is not higher than 5.0*10 -4 Pa, working gas is argon and oxygen, sputtering pressure is 2~4 Pa, sputtering power is 120~180 W, and growth time is 2~4 h.

3. The method for preparing a laser-induced ZnO-MgO nanostripe solar blind UV photodetector according to claim 2, characterized in that: In the ZnO-MgO composite target, the atomic ratio of ZnO to MgO is 50:50; In the radio frequency magnetron sputtering process, the flow ratio of argon and 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 the step S3, the frequency doubling crystal is a barium metaborate crystal; the polarization adjusting assembly includes a first half-wave plate, a polarization beam splitter prism and a second half-wave plate which are sequentially arranged; the scanning processing parameters include: the laser single pulse energy is 30-50μJ, and the scanning speed is 0.8-1.6mm / s.

5. The method for preparing a laser-induced ZnO-MgO nanostripe solar blind UV photodetector according to claim 4, characterized in that: The pulse duration of the femtosecond laser is 200-350fs, and the repetition frequency is 5-15kHz; The magnification of the objective lens is not less than 50x, and the numerical aperture is not less than 0.

8.

6. The method for preparing a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector according to claim 1, characterized in that: In the step S4, in the vacuum evaporation plating process, first preheat for 8-12 min with 15-25 mA current, then grow for 8-12 min with 45-55 mA current, and the vacuum degree is not higher than 8.0×10 -4 Pa.

7. The method for preparing a laser-induced oxygen-zinc-magnesium nanostripe solar-blind ultraviolet photodetector according to claim 6, characterized in that: In the step S4, the surface cleaning method is nitrogen blowing; the metal electrode layer is an Al electrode layer.

8. A laser-induced ZnO-MgO nanoribbon solar blind UV photodetector, prepared by the method of claim 1, characterized in that: From bottom to top, it includes a substrate, a MgZnO nanostripe layer and a metal electrode layer. 9.The laser-induced ZnO-MgO nanostripe solar-blind UV photodetector according to claim 8, wherein: The responsivity peak of the detector is located at 270-280nm, and the response cutoff edge is located at 290-310nm.

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