Influence of oxygen pressure on the growth and physical properties of pulsed laser deposited Cu2O thin films

Abstract

Copper oxide (Cu2O) thin films are prepared by pulsed laser deposition (PLD) technique at different oxygen pressure (PO2). The structural, morphological, optical and electrical properties of the grown thin films are investigated systematically. XRD pattern indicates the polycrystalline nature and pure Cu2O phase thin films. The crystallinity and grain size are found to be improved with oxygen gas pressure (PO2). AFM and FESEM analysis described the dense and crystalline morphologies with minimal film roughness. AFM analysis illustrates the increased mean height and the average parameter of the grain with PO2. UV–visible optical spectra has shown large absorption (% A) of light with an apparent shift in the optical band gap from 2.56 to 2.5 eV with an increase in PO2. The thin films are quite transparent in the visible region above 500 nm. The room temperature electrical resistivity of the films is of the order of ~103 Ω-cm. The crystallography, density of defects and the energy gap appraise the film resistivity. The p-type conductivity of Cu2O is related to the presence of Cu-vacancies. The obtained activation energy and current–voltage (I–V) properties, highlight the potential applications of Cu2O films.