Effects of temperature and pressure on the structural and optical properties of ZnO films grown by pulsed laser deposition

ZnO thin films were deposited on fused silica via pulsed laser deposition (PLD) at substrate temperatures from 300°C to 800°C and ambient oxygen pressures ranging from 10−2 mTorr to 240 mTorr. X-ray diffraction (XRD) and Raman spectra indicated that wurtzite ZnO was obtained in all cases. The highly c-oriented ZnO films were obtained for oxygen pressures above 11 mTorr. The room-temperature photoluminescence (PL) spectra demonstrated that all the films exhibited strong near-band-edge (NBE) emission, while deep-level (DL) emission was also observed in films deposited at oxygen pressures below 80 mTorr. From analysis of the XRD, Raman and photoluminescence PL data, an optimal condition was identified for the deposition of highly crystallized ZnO films.