Direct-contact type image sensors using a novel amorphous-silicon photodiode array

A novel type of amorphous-silicon (a-Si:H) photodiode array for direct-contact type (lens-less) line image sensors was developed. A U-shaped top ITO (tin-doped indium oxide) contact and a rectangular a-Si:H window resolves the accumulation of dust from the documents at the steps of the light window. Semi-insulating Al-Si-N and insulating SiN/sub X/ stacked films are successfully applied to the surface protection layer to prevent a charge buildup by friction with documents.<
>