Preparation Of ZnGa₂O₄ Material By Vacuum Technology And Its Photoelectric Properties

In recent years,wide-bandgap semiconductor materials such as gallium oxide（Ga₂O₃）,gallium nitride（Ga N）,silicon carbide（Si C）and zinc oxide（Zn O）have been widely used in power electronics,semiconductor lighting,ultraviolet detection,radio fre-quency and microwave devices due to their stability in high pressure and high temperature environments,high working efficiency,high energy conversion rate,and low sensitivity to radiation interference.Among them,the ternary alloy ZnGa₂O₄,as a direct bandgap semiconductor material with a bandgap width of up to 5.2 e V and excellent chemical stability,is considered an ideal material for deep ultraviolet（DUV）photo-electric devices.Moreover,ZnGa₂O₄ has a unique Zn²⁺and Ga³⁺bivalent cation structure,which is prone to cation substitution and inverse defects,and can achieve electrical property adjustment of ZnGa₂O₄ by controlling the growth conditions without doping.Currently,ZnGa₂O₄ is widely used in field emission display and electroluminescent devices due to its excellent luminescence purity and good low-voltage cathodolumines-cence characteristics,but research on the preparation of ZnGa₂O₄ thin film and their ap-plication in ultraviolet photoelectric devices is limited.Based on this,this thesis focuses on the growth of high-quality ZnGa₂O₄ thin films and their photoelectric properties,using vacuum physical preparation techniques such as pulsed laser deposition（PLD）,vacuum thermal evaporation,and laser-assisted chemical vapor deposition.By adjusting the growth parameters,the controllable growth of high-quality ZnGa₂O₄ materials was achieved,and the photoelectric properties of ZnGa₂O₄ were studied by preparing photo-electric detection devices on this basis.This study not only provides experimental support for the vacuum preparation of high-quality ZnGa₂O₄ materials but also provides feasible technical approaches for the application of ZnGa₂O₄ in DUV photoelectric devices.The main work of this thesis includes the following parts:1.Preparation of ZnGa₂O₄ thin films by pulsed laser deposition（PLD）technique.In this work,ZnGa₂O₄ thin films were prepared on substrates such as aluminum oxide（Al₂O₃）,p-Si<100>,and p-Si<111>using the pulsed laser deposition technique.The ef-fects of preparation conditions on the morphology,crystalline quality,and optical prop-erties of the ZnGa₂O₄ thin films were systematically studied using characterization tech-niques such as scanning electron microscopy（SEM）,X-ray diffraction（XRD）,absorption-transmission spectroscopy,and photoluminescence（PL）.The optimal condi-tions for film deposition were investigated by changing different preparation parameters.The results showed that ZnGa₂O₄ thin films prepared by PLD had good crystalline quality,dense structure,and no obvious holes,and exhibited excellent optoelectronic properties,providing a research basis for their application in optoelectronic devices.2.ZnGa₂O₄ thin film deep ultraviolet（DUV）photodetector based on metal-semi-conductor-metal（MSM）structure.On the basis of high-quality thin film growth,an Au-ZnGa₂O₄-Au MSM photodetector was designed and fabricated,and its photoresponse characteristics were studied.The experimental results showed that the device exhibited excellent photoresponse characteristics in the DUV range of 240 nm to 280 nm.The pho-tocurrent was maximum when the incident wavelength was 262 nm.Under the condition of a working voltage of 10 V,the dark current and photocurrent were 4.16 p A and 8.50n A,respectively,and the photo-to-dark current ratio was 2043.The maximum responsiv-ity of the device was 7.02×10^-6A/W.In addition,the device exhibited good repeatability and stability,with rise and fall times of 753 ms and 283 ms,respectively.The experi-mental results demonstrated that ZnGa₂O₄ thin film materials prepared by PLD have good application prospects in DUV photodetectors.3.Preparation of ZnGa₂O₄ materials by other vacuum growth techniques.Due to the limitations of the fixed target composition ratio and difficult achievement of large-area uniform films in PLD technology,we prepared ZnGa₂O₄ materials using vacuum thermal evaporation and laser-assisted chemical vapor deposition techniques.In the experiments,different component structures of ZnGa₂O₄ thin films were prepared by flexibly adjusting the proportion of evaporated source materials（Zn O and Ga₂O₃ powders）using vacuum thermal evaporation technique.In addition,by adjusting the different atmosphere envi-ronments and target distances in the tube furnace,ZnGa₂O₄ materials with different struc-tures were prepared using laser-assisted chemical vapor deposition technology,and the optoelectronic properties of the materials were studied.This work provides new ideas for controlling the structure and optoelectronic properties of ZnGa₂O₄ materials.