Characterization of ZnO thin film synthesized on alumina-rich spinel substrate by magnetron sputtering

Zinc oxide (ZnO) thin film has been epitaxially grown on (1 1 1) Mg0.4Al2.4O4 substrate by RF-magnetron sputtering. In resonant Raman scattering, higher-order longitudinal optical phonon modes were clearly observed, revealing high optical quality of the ZnO film. Optical absorption indicated a visible exciton absorption at room temperature. The near band edge emission showed a red shift due to the shrinkage of the band gap with increasing the temperature.