Deep ultraviolet emission of ZnO films prepared by RF magnetron sputtering at changing substrate temperature

ZnO films with deep ultraviolet emission on (0 0 0 6) sapphire substrates were prepared by RF magnetron sputtering at periodically changing substrate temperature. It is found that the as-prepared ZnO films consist of the obvious multilayered structures from the SEM images of their cross-sections. Room temperature photoluminescence of ZnO films with multilayered structure shows two emissions centered at 332 and 388 nm with 260 nm excited wavelength. The strong deep ultraviolet emission at 332 nm is due to the O 2p dangling-bond state in the multilayered structure of ZnO films. Raman scattering spectrum of sample shows that such structured ZnO film possesses strong compressive stress.