Photoluminescence study of ZnO structures grown by aqueous chemical growth

ZnO micro-structures were deposited by aqueous chemical growth on Si (100) substrates, their morphology and size depending on the growth period. Characterization of the structures was performed using X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Photoluminescence spectra recorded at 18 and 295 K for 325 nm CW excitation indicated that these are strongly affected by the morphology of the structures. Rods and tubes emit stronger UV radiation, in contrast to stronger yellow-green emission observed for flower-like structures. A red shift of the UV emission was found for increasing input power, while, thermal annealing of the samples induced stimulated emission for quite high excitation intensities.