Zno Uv Detector

Ultraviolet (UV) detectors have been much studied because of its important applications in many fields. In recent years, the solid-state UV detectors have been used widely with the development of the preparation method of materials. Znic oxide (ZnO) is an important wide band gap semiconductor materials and has been used in the areas of optoelectronics, electronics and UV detectors.The study of ZnO has some progresses in the last decade. Most of them are about doping ZnO. But there were few previous reports on doping AZO(ZnO:Al) film used for ultraviolet detective application. In this paper, AZO thin films with different Al³⁺ concentration were prepared by RF sputtering method. Then the UV detector based on AZO films had been fabricated, the properties of the film and detector were studied in details.The AZO thin films were prepared on quartz substrates. The effects of Al concentration and annealed temperature on the properties of the films were studied. It was revealed that wurtzite structure with (002) orientation AZO thin films were obtained at Al concentration below 20 atomic percent (at%). Annealing temperature has strong influence on the properties of the films. After annealed at 600℃for an hour, the internal stress of thin film decreased, the intensity of (002) diffraction peak increased, the crystalline of thin film was better. The absorption edge had obvious blue shift with the improving of Al concentration. The band gap Eg was 3.93eV with dopant concentration of 20at%. The annealing's effects on the properties of the films were obvious. With increasing the annealing temperature, the absorption edge had blue shift first, then red shift. The films analyzed by EDS indicated that Al concentration of the films were higher than that in ceramic targets.The Au film electrodes was deposited on ZnO by vacuum evaporation, therefore photoconductive UV detectors based on ZnO thin films by using an MSM structure with interdigital (IDT) configuration ,were fabricated. Responsivity of 11A/W at 5V bias for 370 run light is achieved for the film doped with 5at%Al, decreases one order in responsivity for visible light over 400nm. The peak of response had obvious blue shift with increase in Al concentration. The electrical properties of the AZO thin films were studied. A minimum resistance of the film was obtained at a doping concentration of 5at%. The detector has high responsivity after annealed at 600℃. The time response of the detector has better repeatability. Rise time of the detector is faster than fall time. A 3×3 array detector had been fabricated. The test results indicated that the array detector had high response.