Abstract
ZnO thin films were grown by metalorganic chemical vapor deposition on (0001) Zn- and O-polar surfaces of ZnO substrate. The surface morphology of these films was investigated by micro-Raman scattering and scanning electron microscopy. In the case of Zinc-polar face and using back scattering configuration, two new Raman bands were observed at 398 and 584.5 cm(-1). They have been interpreted as quasi phonons TO (qTO) and LO (qLO) respectively. The origin of these modes was attributed to the particular morphology of ZnO films grown on Zn-polar face, which consists in c-axis nano-platelets, randomly tilted from the substrate. qTO and qLO frequencies have been calculated using the model of Loudon. SEM observation is in agreement with our Raman interpretation. (C) 2012 Elsevier Ltd. All rights reserved.