Study On Solar Blind Uv Detector Based On ZnGa₂O₄ Flim

Since the middle and late last century,semiconductor technology has developed rapidly.Various functional devices derived from semiconductor materials have greatly liberated human life and promoted the development of society.They are indispensable to production and life.Ultraviolet detection technology is widely used in military communication,missile early warning tracking,fire detection lock,disaster weather prediction,sea surface pollution monitoring and biological medical and other military and civil fields due to its advantages of simple detection mode,high concealed security,low false alarm probability and low false alarm rate.ZnGa₂O₄ is a kind of broad-band oxide semiconductor with cubic spinel structure.Due to its good chemical stability,thermal stability,corrosion resistance and ultra-wide band gap of about 5.2 eV,ZnGa₂O₄ is an ideal material for preparing UV detectors.In recent years,it has also begun to enter the public’s view and been studied.In this paper,a metal-semiconductor-metal UV photodetector based on ZnGa₂O₄ thin film was prepared by RF magnetron sputtering.The relationship between substrate temperature and film quality and photoelectric properties was studied in detail.In addition,the photoelectric characteristics of the detector at high temperature were tested by heating the device with a heating table.The high temperature characteristics and current transfer mechanism of the device from 25℃to 325℃ were discussed in detail.The specific experimental content and research results are as follows:（1）ZnGa₂O₄ thin films were deposited on c-plane sapphire substrate by RF magnetron sputtering.The experimental parameters such as substrate temperature,RF power and atmospheric pressure were adjusted by controlling variable method.The growth effects（film thickness and surface properties）were tested and compared to find the best growth conditions and obtain high-quality ZnGa₂O₄ thin films.According to the experimental results,increasing the substrate temperature can not only improve the crystal quality of ZnGa₂O₄ film to a certain extent,but also increase its band gap width and obtain higher quality semiconductor materials.（2）ZnGa₂O₄ metal semiconductor metal solar blind ultraviolet photodetector was prepared and discussed by RF magnetron sputtering.The effects of growth and measurement temperature on photoelectric properties were considered in detail.Ohmic contact is formed between the films of all samples and titanium/gold electrodes,and the photodetector shows good solar blind photoelectric performance.Under 10 V bias,the light-dark current ratio of the device can reach 7 orders of magnitude,and it also has extremely fast response speed.In addition,the dark current and photocurrent of the device are measured in the temperature range of 298 K to 598 K,and the mechanism is discussed.It is found that the dark current increases monotonously with the increase of temperature;Taking 423 K as the boundary,the photocurrent first decreases and then increases.The non monotonic phenomenon of photocurrent may be affected by carrier mobility and intrinsic carrer concentration.（3）Based on the ZnGa₂O₄ thin films,high-quality Ga2O3 thin films were prepared by RF magnetron sputtering,Ga2O3/ZnGa₂O₄ heterojunction UV photodetectors were constructed,and their photoelectric properties were tested.The device shows obvious rectification effect,indicating that a Schottky junction is formed between Ga2O3 and ZnGa₂O₄,and the device has a fast response speed.In addition,the detector also has a certain self power supply ability.