Abstract: ZnO/Cu₂O heterojunction films with triangular pyramid surface morphology were electrodeposited potentiostatically on the FTO. The morphology and crystalline phase of obtained films were characterized by field emission scanning electron microscopy(FESEM) and X-ray diffraction(XRD). The surface photovoltage properties of Cu₂O and ZnO/Cu₂O heterojunction films were investigated through surface photovoltage spectrum(SPS), field-induced surface photovoltage spectrum(FISPS) and phase spectrum(PS). The results show that compared to Cu₂O films, the surface photovoltage response of the ZnO/Cu₂O heterojunction films are extended to 600—800 nm. According to the principle of SPS, FISPS and PS, the extended photovoltage response is ascribed to the transition of deep level in Cu₂O which is enhanced by the interfacial electric field between ZnO and Cu₂O in the direction from ZnO to Cu₂O. The photoinduced electron-hole pair germinates from deep level transition of Cu₂O in ZnO/Cu₂O heterojunction films can disassociate and transmit efficiently by the aid of this strong interfacial electric field.

Key words: ZnO/Cu₂O heterojunction, Surface photovoltage spectrum(SPS), Field induced surface photovoltage spectrum(FISPS), Interfacial electric field