Structural and Electronic Properties of Electrodeposited Heterojunction of CuO/Cu2O

Abstract

The structures and the electronic band states of the electrodeposited thin film CuO/Cu2O heterojunction have been studied by means of the X-ray diffractions (XRD) and the X-ray absorption spectra (XAS) with different grazing angles of the incident X-ray beam using the synchrotron radiation. The heterojunction of about 2 ?m consists of n-type Cu2O (~1 ?m) and p-type CuO (~1 ?m) thin films bi-layer. Scanning electron micrographs (SEMs) show the existence of two different polycrystalline grain layers and the XRD reveals that the different grain layers are high quality CuO-type and Cu2O-type structures respectively. Photoactive performances of the Ti/CuO/Cu2O/Au heterojunction are Voc of ~210 mV and Jsc of ~310 mA/cm2. It reveals that the Cu2O grains are grown from the surfaces of the CuO polycrystalline grains and make very good contact with the CuO grains. It is found that the XAS of CuO/Cu2O heterojunction are convoluted independently by X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structures (XANES) spectra of the Cu2O and CuO grains, depending on the grazing angles. Present study reveals that bottom of the conduction band (Cu-4pp) of the Cu2O in the CuO/Cu2O heterojunction reduces by 0.57 eV relative to the Ti/Cu2O ohmic contact.