Spray pyrolysis synthesis of a semi-transparent p-CuCrO2/n-ZnO heterojunction: Structural, optical, and electrical properties

A CuCrO2/ZnO heterojunction diode was successfully fabricated by ultrasonic spray pyrolysis. The high quality of the layers constituting the diode was determined by XRD, SEM, Ellipsometry, I-V and Impedance spectroscopy measurements, as well as by their optical properties. Backscattered electron microscopy allowed to resolve each layer of the junction. The high density of the films was inferred through the refractive index of the films: 2.02 and 1.97 for the ZnO and the CuCrO2 layers, respectively. I-V measurements showed the characteristic rectification of the diodes, approaching a figure of 107 @ +/- 4.5 V. Impedance spectroscopy results showed four different activation energies attributed to the bulk conductivities of CuCrO2 and ZnO, and to the CuCrO2-ZnO and Au-CuCrO2 junctions. The %T of the diode varied from 20% at 400 nm up to 70% at 700 nm, leading to a device that can be classified and used as a semi-transparent diode.