Si nanowire metal–insulator–semiconductor photodetectors as efficient light harvesters

Novel ITO-Si nanowire (NW) metal?insulator?semiconductor (MIS) photodetectors were fabricated by using n-type Si NWs as detection units and ITO films as top gate electrodes. Measurements on the Si NW based device reveal a significant photoresponse, including photocurrent generation with an external quantum efficiency (EQE) of ~ 35% at a peak wavelength of 600?nm at zero external bias, and with an EQE of 70% at a peak wavelength of 800?nm at ? 0.5?V bias. The NW device shows a flat and low reflectance and almost constant EQE up to a 60? incident angle of illumination, demonstrating efficient visible-light harvesting by the Si NW antenna.