Fabrication of single phase transparent conductive cuprous oxide thin films by direct current reactive magnetron sputtering

A series of cuprous oxide thin films with various thicknesses were deposited on quartz substrates by direct current reactive magnetron sputtering at room temperature. The crystal structure, element composition, morphology, optical and electrical properties of the samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), optical absorption/scattering, and sheet resistance measurement, respectively. XRD patterns indicated that single phase with the preferred orientation in (111) plane could be obtained by controlling the appropriate film thickness and oxygen pressure. The binding energy of Cu 2p and O 1s confirmed that the chemical valence of Cu in the samples is +1. With the increase of film thickness, surface roughness of the samples increased and the optical band gap edge shifted toward longer wavelength.