Study of Electron States in Photosensitive Amorphous Titanium Oxide Films deposited by Plasma Process

点击翻译按钮获取中文摘要

Titanium oxide films prepared by a magnetron sputtering are in amorphous state and show high sensitive photo-conduction for UV radiation and excellent wet ability. These films contain a lot of OH groups in its film. These are attributed to the compensation of the defect states by OH groups included. In this study, it is also shown that the responses of the photo-conductive current are very slow with time constant of over 10 minutes. When the light was removed, the photocurrent continued to flow for long time with several hour time constants. These mean that photo-excited carriers could not recombine with the excited holes or electrons and iterated capture and emission between conduction band and capture states. These responses are shown as a extended exponential function. Furthermore, photo-current is drastically influenced by the environmental gas, especially oxygen gas. In the environmental gas including oxygen, photocurrent decreases with reverse proportional relation for oxygen partial pressure. It is shown from considering the life time of the photo-excited carriers, these surface reactions of the film between environmental gasses and film surface are well suggested as to be an linear reaction. An application target for these materials has been suggested to be effective for an environmental oxygen gas sensor and coating materials for plastics. Amorphous titanium coatings on the plastics for cutting UV light were shown for plastic windows and automobile head light.