Effect of nitrogen reactive gas on ZnO nanostructure development prepared by thermal oxidation of sputtered metallic zinc

ZnO thin films were prepared from metallic zinc and metallic zinc + zinc nitride mixture by thermal oxidation. The DC-magnetron sputtering technique was used to deposit the films under argon and argon + nitrogen atmosphere, respectively. The oxide thin films prepared by this method have wurtzite structure without any preferential orientation. Compared to ZnO films grown from metallic zinc that were deposited under Ar only (ZA), ZnO films grown from metallic zinc under nitrogen-rich atmosphere (ZAN) showed a considerably lower average grain size, and growth of abundant nanorods. XPS analysis failed to detect any remaining nitrogen in the prepared films. However, the analyses suggest that nitrogen used in this process can lead to an enhancement of film densification. Room temperature photoluminescence (PL) spectra of both films revealed five emission bands located at the same positions: a predominant exciton ultraviolet (UV) (396 nm), a green (530 nm), a violet (422 nm), a blue (484 nm), and a band to band emission at 354 nm. In addition, ZAN displayed another intense UV emission band peaked at 377 nm.