DEVELOPMENT OF UV ACTIVE AMORPHOUS TIO2 THIN FILMS AND APPLICATION TO ENVIRONMENTAL SENSOR

采用远程等离子体增强(RPE)化学气相沉积法制备的二氧化钛薄膜为非晶态，对紫外光具有很高的感光能力和良好的润湿性能。这些膜在其膜中含有大量的羟基。这归因于含OH基团对缺陷态的补偿。在本研究中还发现，光导电流的响应非常慢，时间常数超过10分钟。当光被移除时，光电流以几个小时的时间常数持续流动很长时间。这意味着光激发载流子不能与激发的空穴或电子复合，并在导带和俘获态之间重复捕获和发射。此外，光电流受环境气体，尤其是氧气的影响很大。在含氧的环境气体中，光电流与氧分压成反比。从光激发载流子的寿命来看，环境气体与薄膜表面的这些表面反应很好地被认为是线性反应。这些材料的应用目标已被建议用于环境氧气体传感器和塑料涂层材料。

Titanium oxide films prepared by a remote plasma enhanced (RPE) CVD 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. 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.