Effect of Post-heat treatment on the physical properties of CuO films

Abstract

Nanometric CuO and Cu2O films were manufactured by high temperature magnetron sputtering (T = 400 °C) and possess properties that make them suitable as electron and hole transport films, respectively, in various types of solar cells, such as perovskite and organic, as well as in optoelectronic devices. In this study, the effect of oxygen flow on optical properties and the influence of post-deposition treatment on the topographical and connectivity characteristics of thin CuO and Cu2O films were investigated. The surface topography was analyzed using atomic force microscopy (AFM), revealing an increase in surface roughness as the film thickness increased from 100 nm to 340 nm. Post-deposition heat treatment performed at T = 400 °C for 60 min under high vacuum conditions (~104 Torr) resulted in a substantial increase in the contact angle from 102° to 120°, indicating a transition to more hydrophobic surface behavior. The optical transparency of the investigated films was approximately 45% in the visible and near-infrared spectral range. The estimated bandgap values ranged from 1.54 to 1.67 eV and from 1.97 to 2.22 eV for Cu2O films. Optimizing the thickness of the films, as well as their structural and electronic properties (e.g., grain size and charge mobility properties), can lead to significant improvements in the performance of the films obtained.