Variable spectral response photodetector based on crystalline/amorphous silicon heterostructure

A novel photodetector based on a p-i-n amorphous silicon/n-p crystalline silicon stacked heterostructure, which exhibits either infrared or visible response, depending on the polarity of the applied bias is described. The energy gap and the thickness of the layers inside amorphous diode have been optimized to obtain a wavelength selection (centered at 480 nm and 780 nm) with high rejection ratio and good quantum efficiencies. 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 conductivity transparent film deposited on the top of the device.