Materials studies of copper oxides obtained by low temperature oxidation of copper sheets

Inexpensive and stable solar cells based on oxide materials are currently strongly investigated. The surest candidates are copper oxides, which unlike to other metal oxides display strong absorption across the visible range. Although, copper oxides thin film can be deposited by the number of methods, cost effective techniques applicable for large scale production are necessary. Therefore, the main focus of this paper was turned to the simple and time effective thermal oxidation of copper sheets using relatively low temperatures 200–400 °C. The surface pretreatment was selected in order to support homogeneous growth conditions. The basic material research presented here included the morphological, compositional and microstructural aspects of grown copper oxides. The surface roughness of manufactured layers for investigated temperature range was described either by AFM microscopy where Ra was assessed between 8.9 and 67.6 nm and also by the optical method where calculated haze factor ranged from 34 to 79.3%. Microstructure and phase composition studies were performed by means of TEM and XRD supplemented by XPS surface analysis confirming the dominating phase of copper (I) oxide capped with thin surface CuO layer. Finally, the optical properties were described allowing to determine the sample absorptivity and band gap energy varying in the range 2.43–1.93 eV.