ZnO/Cu2O异质结中深能级表面光伏特性

Surface Photovoltage Properties of Deep Level in ZnO/Cu_2O Heterojunction Films

采用恒电压沉积法在导电玻璃(FTO)上制备了具有三棱柱金字塔状的ZnO/Cu2O异质结薄膜.利用场发射扫描电镜(FESEM)与X射线衍射仪(XRD)对薄膜的微观形貌和晶体结构进行了表征.利用表面光电压谱(SPS)、场诱导表面光电压谱(FISPS)和相位谱(PS)研究了单一Cu2O与ZnO/Cu2O异质结薄膜的表面光伏性质.结果表明,与单一Cu2O薄膜相比,ZnO/Cu2O异质结薄膜的光伏响应范围拓展到了600～800nm.根据SPS,FISPS和PS的作用原理,拓展部分的光伏响应归因于ZnO/Cu2O异质结中Cu2O层的深能级跃迁,该跃迁在ZnO-Cu2O界面电场(方向由ZnO指向Cu2O)的作用下得到加强,同时深能级跃迁产生的电子-空穴对在ZnO-Cu2O界面电场的作用下得到了有效分离和传输.

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.