Characterization of photoluminescence of Al-doped hydrothermal ZnO films

The Al-doped ZnO (AZO) films were synthesized in hydrothermal method on quartz substrates. The films, grown under the optimized conditions, were characterized with X-ray diffraction, scanning electron microscopy, and photoluminescence (PL) spectroscopy. Two wide peaks of the PL spectrum were observed, one is the ultraviolet (UV)-violet peak, the other is the green-red peaks. The results show that the Al-doping and temperature strongly affect the PL spectra of the films, consisting of the hexagonal, c-axis preferentially orientated, ZnO nano-rod with conical ending. For example, the intensity of UV and violet peaks rose up with an increase of the Al-content, maximizing at Al 10.0% (wt). As the temperature increased from 10 to 267 K, the UV and violet peaks remained almost unchanged, but the green-red emission peaks quenched. Possible mechanisms responsible for the quenching were tentatively discussed.