Control of the Cu2O crystal orientation and the application of a ZnO/Cu2O self-powered photodetector in visible-light-encrypted communication

Abstract

Reducing carrier trapping in the grain boundary of semiconductor materials can improve the carrier transport. Adding Na₂EDTA in the electrolyte can regulate the growth process of Cu₂O thin films electrochemically deposited at low temperature, improve the crystal quality, and transform from the polycrystalline structure into a single-crystal-like structure oriented along the (111) crystal plane. As a result, the interface transfer resistance of ZnO/Cu₂O heterostructure devices is reduced, the photogenerated carrier transport ability is improved, and the self-powered photoresponse properties of heterostructure devices are improved. Based on the dual-band photoresponse characteristics of ZnO/Cu₂O, a device without bias voltage was applied in the “OR” gate of a UV and visible dual-band light controlling digital logic circuit. The encrypted optical signal was realized and the security of visible light communication was improved by the encoded UV and visible dual-band light.