Deposition Optimization and Property Characterization of Copper-Oxide Thin Films Prepared by Reactive Sputtering

Copper-oxide (CuO) thin films were prepared by reactive sputtering of Cu onto Si wafers and characterized using a statistical design of experiments approach. The most significant factor in controlling the electrical resistivity and deposition rate was determined to be the O₂ fraction. The deposited CuO thin films were characterized in terms of their physical and chemical properties, using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD), and 4-point resistance measurements. The deposited copper thin films were characterized by XPS and XRD analyses to consist of Cu²⁺. The CuO thin films of highest resistivity exhibited superior rectifying responses with regard to n-type Si wafers, with a current ratio of 3.8×10³. These superior responses are believed to be associated with the formation of a charge-depletion region originating from the p-type CuO and n-type Si materials.