We report on the fabrication of a heterojunction photodiode for the visible range that consists of a transparent insulating ZnO overlayer and a transparent semiconducting n-ZnO layer on p-Si. For device isolation, we implanted Si+ ions into the n-ZnO layer. We have obtained a wide-range spectral responsivity curve for our isolated photodiodes, which showed a maximum quantum efficiency of 70% at 650 nm and a minimum of 10% at 420 nm. However, they exhibited an efficiency drop at 380 nm in the near-ultraviolet because the ZnO layers absorbed the photons of higher energy before they reached p-Si. The ion-beam-induced isolation considerably reduced dark leakage currents in our devices when the dose of Si ions was as high as 5×1015 cm−2.

Influences of leakage currents on the transport properties and photoelectric effects in heterojunctions composed of colossal magnetoresistance manganites and Nb-doped titanates J. Appl. Phys. 111, 07D724 (2012); 10.1063/1.3679413Laboratory pentacene and parylene evaporation systems for fabricating organic thin film devices