Study And Preparation Of TiO₂Ultraviolet Photodetector

Ultraviolet （UV） detectors are very important in scientific research, military,aerospace and many industrial control area. There are some disadvantages about thetraditional silican UV detectors and photomultiplier tube,such as big volume, highpower consumption, slow response, short life, easy to damage, and must be filteredlight film.They don’t meet the needs of modern high-speed information on varioustypes of UV sensors any more, therefore, the research and development ofminiaturization, intelligence, and high reliability, low cost new solid semiconductorultraviolet light sensor has become an urgent task and important subject.TiO₂is a kind of wide-band semiconductor, and it has many advantages such aslow price, good weathering resistance, physical and chemical stability, suitablephotoelectric characteristics, and there are many ways to prepare the material, so ithas shown a unique advantage in the preparation of UV detectors. We make nanoTiO₂film as the material of UV detectors to solve the problems of SiC and GaN￡such as the lack of appropriate substrate when preparing large area semiconductor,the UV detector array and UV imaging system. We can overcome the limits ofsemiconductor materials, equipment and processes by using TiO₂material, so it isvery important in scientific research and has good application prospect.In this paper, we use the unique advantages of TiO₂materials to prepare UVdetectors.First of all, TiO₂thin films were prepared by sol-gel method. Then the featureof TiO₂thin films was studied by XRD, SEM, AFM, XPS, UV-Vis spectrum. Toprepare better TiO₂thin film we study and summarize the experimental conditionsof the matrix material properties.Then, MSM UV detectors with Pt electrode were fabricated based on TiO₂films.Under5V applied bias, the dark current of the UV detectors was only1.6nA. Underirradiation of260nm UV light, the photo current was517μA.,which was five ordersof magnitude compared with the dark current. In light responsiveness of UV detectors, there is a clear absorption edge When the wavelength of light reach330nm,which fit well with the absorption spectrum of the material. At260nm, opticalresponse reach its maximum which was362A/W.At last, according to the optical and electrical properties of TiO₂, When UVlight intensity increases, TiO₂UV detector will produce photocurrent, and thevoltage across the load resistor which connected with the detector will increases, thenonlinear relationship of light intensity and the voltage across the load resistor canbe obtained. We use this relationship to write programs, design of peripheral circuits,produced a fully functional TiO₂UV detectors. After repeated testing, the respons ofthe detector was rapid,and the measurement results was accurate, which meet thedesign objectives and requirements.