Preparation and Properties of ZnSe/Zn3P2 Heterojunction Formed by Surface Selenization of Zn3P2 Film Deposited on ZnTe Layer

Abstract

ZnSe/Zn3P2 heterojunctions with a substrate configuration were fabricated using a series of cost-effective processes. Thin films of ZnTe and Zn3P2 were successively grown by close-spaced sublimation onto Mo-coated glass substrates. ZnSe layers thinner than 100nm were formed by annealing the Zn3P2 films in selenium vapor. Surface selenization generated a high density of micro-cracks which, along with voids, provided shunt paths and severely deteriorated the diode characteristics. Annealing the Zn3P2 film at 300ºC in a ZnCl2 atmosphere before surface selenization produced a dense microstructure and prevented micro-crack generation. The mechanism of micro-crack generation by the selenization was described and the suppression effect of ZnCl2 treatment on the micro-crack generation was explained. ZnSe/Zn3P2 heterojunctions with low leakage current (J0 < 1 µA/cm2) were obtained using an ptimized surface selenization process with ZnCl2 treatment. However, the series resistance was very high due to the presence of an electrical barrier between the ZnTe and Zn3P2 layers.