Abstract
A dual-polarity, photovoltaic photodetector for red-green dual-wavelength detection is demonstrated, operating in the self-powered mode. It is based on a core-shell n-InGaN nanowire/p-Cu(2)O heterostructure with inner upward energy band bending and near surface downward energy band bending. This produces negative photocurrent for red light illumination and positive photocurrent for green light illumination. Balanced negative and positive photocurrents are obtained by optimizing the Cu(2)O layer thickness. The imaging capability is experimentally demonstrated for real-life red and green color recognition on a mobile phone display.