Interfacial charge transfer in ZnTe/ZnO nano arrayed heterostructures and their improved photoelectronic properties

Abstract

The demand for low-cost high efficient photoelectronic devices tends to drive the present need for investigations on advanced multi-functional semiconducting nanostructures. In this regard, the physico-chemical traits of sonochemically processed ZnTe nanostructures and hydrothermally grown ZnO nanostructures were studied using Raman, UV vis absorbance, X-ray photoelectron spectroscopy and high resolution microscopic tools. The p-n ZnTe/ZnO heterojunctions were then fabricated via spin casting a colloidal ZnTe suspension on periodically aligned ZnO nanowires and investigated for their photoelectronic functionalities. The current-voltage (I-V) characteristics revealed an obvious rectifying behaviour with the forward current and rectification ratio getting improved on lowering the threshold voltages. The series resistance of the diodes were additionally studied using the dV/dlnI derivate plots. The stability of the diodes were also affirmed using their time-dependent photo response characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the interface. Finally, the ZnTe/ZnO heterojunction behaviour was assimilated using the electrochemical impedance spectroscopic (EIS) results that were studied individually for ZnTe and ZnO nanostructures and collectively across ZnTe/ZnO heterostructure.