Surface photovoltage study of photogenerated charges in ZnO nanorods array grown on ITO

A well-aligned nanorods array of ZnO was chemically grown on conductive ITO substrate at low temperature. The photogenerated charges at surface and interface were examined by surface photovoltage techniques based on both Kelvin probe and lock-in amplifier with dc bias. The photovoltage response bands related to band-to-band transition and bound excitons were discriminated. We demonstrated the spectrum-dependent transfer characteristic of photogenerated charges at the surface of ZnO nanorods array and the interface between ZnO and ITO.