The blue photoluminescence emitted from ZnO films deposited on glass substrate by rf magnetron sputtering

ZnO films have been deposited on Corning 7059 glass substrates using rf magnetron sputtering. Strong monochromatic blue emission located at 446 nm is observed when excited with 270 nm light at room temperature (RT). The photoluminescence (PL) intensity decreases with increasing oxygen pressure during film deposition and it increases pronouncedly by annealing in vacuum. The blue emission may correspond to the electron transition from the shallow level of oxygen vacancies to the valence band.