VARIABLE SPECTRAL RESPONSE PHOTODETECTOR BASED ON CRYSTALLINE AMORPHOUS SILICON HETEROSTRUCTURE/

A novel photodetector based on a p-i-n amorphous silicon/n-p crystalli ne silicon stacked heterostructure, which exhibits either infrared or visible response, depending on the polarity of the applied bias is des cribed. The energy gap and the thickness of the layers inside amorphou s diode have been optimized to obtain a wavelength selection (centered at 480 nm and 780 nm) with high rejection ratio and good quantum effi ciencies. Absolute values of the quantum yield as high as 80% in both the two spectral bands have been obtained thanks to an Al-doped ZnO co nductivity transparent film deposited on the top of the device.