Observation of a large gate-controlled persistent photoconduction in single crystal ZnO at room temperature

Gate-controlled enhanced photoconductivity at room temperature is reported in single crystal ZnO using moderate bias and band gap illumination. A substantial part of the enhanced photocurrent is retained over a long time as a persistent photocurrent when the illumination is removed but the gate voltage (applied with a polymer-electrolyte gate) is retained. The current on the removal of illumination shows a stretched exponential decay with time constants more than few hundreds of seconds. An explanation based on change in charge state of oxygen vacancy has been proposed. (c) 2011 American Institute of Physics. [doi:10.1063/1.3534790]