A pn-junction between chalcopyrite phosphide semiconductors for photovoltaic application

We report on the fabrication of a pn-junction between II-IV-V-2 type compounds with a chalcopyrite crystal structure such as CdSnP2 and ZnSnP2 for photovoltaic application. In the fabrication process, Cd-Sn precursor thin films were prepared on ZnSnP2 bulk crystals grown by the flux method and the precursor thin films reacted with phosphorus gas to form CdSnP2/ZnSnP2 junction. STEM-EDX analysis and SAED patterns revealed that CdSnP2 was epitaxially grown on ZnSnP2 bulk crystals, indicating that the favourable junction was obtained in the view point of carrier transport. In addition, Zn was also detected in the region of the CdSnP2 thin film due to the diffusion of Zn during phosphidation. This suggests the formation of solid solution (Cd,Zn)SnP2 between ZnSnP2 and CdSnP2, leading to realization of a homojunction. In the J-V measurements of the n-(Cd,Zn)SnP2/p-ZnSnP2 junction, a rectifying behavior was observed. The results in this work are cornerstones for photovoltaic application using II-IV-V-2 type compound semiconductors including phosphides. (C) 2019 The Japan Society physics