Solid state imager having gated photodiodes and method for making same

A method of fabricating an imager array having a plurality of pixels, each pixel comprising a respective pixel thin film transistor and a pixel photosensor, the method comprising, for each respective pixel, the steps of:

• depositing a first conductive layer on a substrate;
• forming a photosensor bottom electrode from said first conductive layer;
• forming a photosensor body disposed on at least a portion of said photosensor bottom electrode, said photosensor body having sidewalls;
• depositing a gate electrode dielectric layer over said photosensor body;
• forming a layer of field plate comprising amorphous silicon on at least a portion of said gate dielectric layer covering said sidewall of said photosensor body and extending completely around said photosensor body;
• and
• forming a common electrode in electrical contact with said field plate.

A radiation imager comprising:

• a substrate;
• a photosensor array disposed on said substrate, said photosensor array comprising a plurality of pixels, each of said pixels being coupled to a scan line and a data line, each of said pixels further comprising:
• a photodiode having a body with sidewalls;
• a thin film transistor (TFT), said TFT being electrically coupled to said photodiode and said scan line and data line so as to enable selective readout of the charge of said photodiode;
• a common electrode disposed in electrical contact with said photodiodes;
• and
• a field belt comprising amorphous silicon disposed around said photodiode sidewalls with a dielectric material being disposed between said field plate and said photodiode body, said field belt being in electrical contact with said common electrode so as to provide an electric field around said photodiode body in correspondence with the potential of said common electrode.