Abstract
Amorphous silicon (α-Si) thin-film transistors (TFTs) have attracted much attention in the application of integrated peripheral circuits on display electronics such as active matrix liquid crystal displays (AMLCDs). Various attempts have been reported to integrate display circuits on the glass substrate. In addition, additional pixel circuits are required to realize so-called high-value added display or sheet computer having input function, especially in mobile equipments. Integration ofα-Si optical sensor is considered to have a potential to be a key technology for realizing photo-sensing functions such as ambient light sensors, image scanners, touch panel, etc. It was found that photo current of theα-Si TFT has good linear dependence on the illumination intensity. In the off region, independent of the bias condition, this good linearity is always tenable. In this thesis, we present detailed studies on the characteristics of photo current on bias conditions, photo-response spectrum, and defect states in theα-Si thin film. Furthermore, photo-response of theα-Si TFT affected by extra defect states creation have been also investigated. Different stress condition cause defect states creation, in turn change photo current. The relation between photo leakage current and defect is proposed and explained characteristics the anomalous illumination behaviors after device degradation.