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

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 5 V reverse bias, the dark current density is 10 nA/cm(2) and quantum efficiency is 18% at a wavelength of 380 nm, with a photoresponse behavior that is linear over 5 decades. (c) 2006 American Institute of Physics.