Amorphous Si:H Contact Linear Image Sensor

A contact linear image sensor using a-Si:H heterojunction photodiode array has been developed. The sensor is composed of a pair of LED array, a rod lens array and a document width linear image sensor in which a-Si:H photodiode array and driving ICs are mounted on the same glass The a-Si:H diode has ITO/p-a-SiC/a-Si:H/metal structure. It exhibits as high as 104 photo-to-dark current ratio and quick photoresponse because of excellent blocking characteristics and large built in potential of heterojunction. The contact sensor has been operated with 1 msec/line scanning speed. Performance tests show excellent results with 8 lines/mm resolution. Images have been satisfactorily recorded using a thermal printer. Moreover, thin film image sensor using a-Si:H TFT will be discussed as a lower cost linear image sensor.