Photovoltaic effect in m-plane orientated ZnOS epitaxial thin films

摘要

We report on the photovoltaic (PV) effect in nonpolar (10 (1) over bar0) orientated ZnO1-xSx (i.e., m-ZnOS) epitaxial thin films. The m-ZnOS films were epitaxially grown on m-sapphire using pulsed laser deposition. Photovoltaic devices were made by evaporating two parallel Au electrodes on the epitaxial m-ZnOS films. The best PV performance was achieved involving the film deposited at 5.5Pa oxygen pressure with an open-circuit voltage of 0.694mV and a short-circuit current density of 122.3 mu A/cm(2). The internal spontaneous electric field along the polar c-axis of m-ZnOS, which lies in parallel to the film surface and perpendicular to the Au electrodes, is the driving mechanism for the separation and transport of the photogenerated carriers. Complementary to conventional solar cells that operate under visible-light, such transparent PV devices can be installed on various windows to generate electricity using ultraviolet light, thereby efficiently extending the deployment of PV technology and the usable wavelength range of the solar spectrum.