Abstract
Nondestructive determination of the polarity of GaN has been achieved by use of coaxial impact collision ion scattering spectroscopy. GaN films were deposited on c-plane sapphire substrates by a two-step atmospheric pressure metalorganic chemical vapor deposition using GaN buffer layers. The correlation between the samples prepared by interrupting the growth sequence at the various stage and their polarity was systematically investigated. It has been found that the polar direction of GaN growth is influenced by the polarity at the interface prior to the deposition of GaN epitaxial layer. We describe the mechanism of determining the polar direction by addressing our recent research related to substrate nitridation, buffer layer, and annealing of buffer layer.
