Temperature dependence of photoconductivity and persistent photoconductivity of single ZnO nanowires

Photoelectrical properties of single ZnO nanowires have been investigated using photocurrent–voltage characteristics measurements varying with excitation photon energy and temperature. It is found that persistent photoconductivity (PPC) exists, and the PPC decreases with decreasing temperature. The temperature dependence of the PPC effect indicates that thermally activated return of electrons from shallow traps is responsible for the PPC phenomenon. The photosensitivity is found to be linear with the applied voltage, and it increases with decreasing temperature. A temperature dependence of photoconductivity gain was introduced to explain the experimental results.