Growth and photoluminescence of ZnO thin films on Si(1Â 1Â 1) by PLD in oxygen adequate ambient

Polycrystalline ZnO thin films were synthesized on Si(1 1 1) substrates by pulsed laser deposition (PLD) under oxygen sufficient condition at temperatures ranging from 550 to 700∘C. The results of in situ reflection high-energy electron diffraction (RHEED) and X-ray diffraction (XRD) show that the (0 0 2) orientation of ZnO thin films is deteriorated, but the full-width at half-maximum (FWHM) of (0 0 2) peak decreases as the substrate temperature (Ts) increases. In photoluminescence (PL) spectra at room temperature (RT), all the ZnO thin films show small ultraviolet (UV) peak FWHMs in the range of 83-95 meV. The thin film prepared at 650∘C exhibits the narrowest UV peak FWHM of 83 meV and the biggest intensity ratio (122) of UV emission (UVE) to deep-level emission (DLE). When the Ts increases to 700∘C, a low-energy peak in the UV region at around 381 nm (3.25 eV) appears, which maybe result from a donor-acceptor-pair (DAP) transition and be a signal of excess incorporation of oxygen in the thin film.