Determination of the polarity of ZnO thin films by electron energy-loss spectroscopy

The polarity of the ZnO film grown on sapphire using an ultra-thin Ga wetting layer has been investigated by electron energy-loss spectroscopy (EELS). The intensity of the oxygen K-edge in electron energy-loss spectrum from the ZnO film shows a prominent difference when the film orientation changes from the (0002) Bragg condition to the (000 (2) over bar) Bragg condition. The EELS study reveals that the ZnO film with very thin Ga wetting layer has the [0001] polarity, which is further confirmed by the conventional convergent beam electron diffraction method. (C) 2003 Elsevier B.V. All rights reserved.