Low leakage p-NiO∕i-ZnO∕n-ITO heterostructure ultraviolet sensor

Abstract

This letter reports a low leakage p-NiO∕i-ZnO∕n-ITO ultraviolet photodiode fabricated at room temperature by ion beam assisted e-beam evaporation. Analysis of its J-V characteristics, and time-dependent behavior, reveals that the dominant source of leakage current stems from deep defect states in the ZnO i layer, with its dynamic response at low signal levels limited by charge trapping in the absorption layer. Under a 5V reverse bias, the dark current density is 10nA∕cm2 and quantum efficiency is 18% at a wavelength of 380nm, with a photoresponse behavior that is linear over 5decades.