Plasma Annealing Effects on the Material Characteristics of Sputtering Deposited CuCrO₂Thin Films

In this study, we prepared a copper chromium oxide film using sputtering deposition. We used microwave plasma under atmospheric pressure for annealing at a temperature of 700°C and a treatment time of 10 min to fabricate a p-type CuCrO2 semiconductor. The film has a composite phase structure, with CuCrO2 as the main structure along with a small amount of CuCr2O4. It was found that as the film thickness decreased, the average grain size increased. A cross-section of the film shows a densely stacked polygonal granular structure. Furthermore, the transmittance of the film improved as its thickness reduced and the grain size increased. This is because larger grain size leads to lower internal stress, in turn reducing the direct bandgap to 2.94 eV. The atmospheric-plasma treatment for forming CuCrO2 is a conducive method for forming hole-carriers required for p-type conduction. The crystallization of the CuCrO2 film proceeds inward from the nucleated surface, which affects the distribution and size of the polygonal granular structure.