Temperature dependence of the optical transitions in electrodeposited Cu2O thin films

Cu2O films on flexible copper and molybdenum (Mo) substrates were prepared by electrodeposition form an alkaline bath. The as-deposited films were p-type and the XRD analysis revealed that the film contains only the Cu2O phase. The thickness of the films was calculated from the interference fringes in the reflection spectra. The Au/Cu2O Schottky diodes were prepared by sputtering a 15 nm thick layer of very pure gold onto the Cu2O films on Mo substrate. The probable optical transitions near the band edge were calculated from the spectral response of the device. The band gap calculated at various temperatures show a linear dependence on temperature and the absolute zero value of the band gap is deduced as 2.206 eV. The 2.493 eV direct transition observed in the room temperature shows a temperature dependence. Evidence of phonon assisted indirect transitions were observed at various temperature regions.