Optical properties of sputtered hexagonal CdZnO films with band gap energies from 1.8 to 3.3 eV

Cd_xZn_1−xO films in a wide range of Cd contents have been grown by reactive direct-current magnetron sputtering. At x ≤ 0.66, the sputtered Cd_xZn_1−xO films are of single hexagonal phase. The optical band gap energies of the Cd_xZn_1−xO films decrease from ∼3.3 eV at x = 0 to ∼1.8 eV at x = 0.66. Correspondingly, the near-band-edge photoluminescence is tuned in a wide visible region from ∼378 to 678 nm. Moreover, the ultraviolet irradiation enhanced PL from the Cd_xZn_1−xO films has been observed.