Effect of annealing on the dark and illuminated I(V) characterization of a ZnO : Ga|Cu$_2$O hetero-junction prepared by ultrasonic spray system

This paper presents the Ultrasonic Spray Pyrolysis system fabrication of gallium-doped Zinc Oxide (ZnO : Ga)|Cuprous Oxide (Cu$_2$O) thin film hetero-junction. The deposition parameters were constant for ZnO : Ga and Cu$_2$O. Structural and optical properties of ZnO : Ga, Cu$_2$O and ZnO : Ga|Cu$_2$O hetero-junction were characterized by $X$-Ray Diffraction method and UV-Vis Spectrometry, respectively. SEM and FTIR were used to reveal the morphology and the nature of the chemical bonds. The electrical properties were measured by an Agilent I–V source meter. The ZnO : Ga|Cu$_2$O hetero-junction was annealed at 350, 400, and 450$^\circ$C and the current–voltage characteristics were measured. The band gaps of ZnO, Cu$_2$O, and ZnO : Ga|Cu$_2$O are $\sim$ 3.27 eV, $\sim$ 2.65 eV, and $\sim$ 3.29 eV, respectively. The annealing temperature improves the hetero-junction quality.