Effect of rapid thermal annealing on photoluminescence and crystal structures of CdZnO films

Hexagonal CdxZn1−xO films with low and high Cd contents (x=0.10 and 0.52) have been deposited by reactive direct-current magnetron sputtering, respectively. The as-deposited CdxZn1−xO films hardly exhibit detectable photoluminescence (PL). Once subjected to rapid thermal annealing (RTA) at sufficiently high temperatures, the CdxZn1−xO films exhibit pronounced PL. For the Cd0.10Zn0.90O films subjected to RTA at 500 °C and above, they are of single hexagonal phase. The enhanced near-band-edge (NBE) emission is somewhat blue-shifted with the increase of RTA temperature. While for the Cd0.52Zn0.48O films, they are transformed into hexagonal (Cd-incoporated ZnO) and cubic (Zn-incoporated CdO) phases due to the RTA at 500 °C and above. The NBE emissions from the two above-mentioned phases are well revealed in the PL spectra.