Growth of ZnO crystal on sapphire and nitridated sapphire substrates at 1000 °C by halide vapor phase epitaxy

Using a halide vapor phase epitaxy (HVPE) technique in which the starting materials are ZnCl(2) generated by the reaction between high purity Zn metal (7 N grade) and Cl(2) gas, and H(2)O, ZnO crystals have been grown at a high temperature of 1000 degrees C on sapphire substrates with and without surface nitridation treatment. It was found that the nitridation treatment resulted in a change of the (11 (2) over bar0) sapphire surface to a (0001) AlN structure, leading to two possible sets of orientations for (0001) ZnO crystals. In addition, the nitridation treatment leads to a smaller average ZnO grain size and a higher density of nuclei. (C) 2009 Elsevier B.V. All rights reserved.