Abstract
The group-III nitrides are mostly grown on sapphire substrates with a low-temperature deposited buffer layers. Since the whole layers are of a large variety in terms of crystal structures and crystal quality, a very versatile characterization technique is necessary to reveal the structures. In this paper. characterization of an extremely thin initial layer, the buffer layer, thick GaN layers, and the whole structure of multilayers are investigated by the X-ray CTR scattering and X-ray reflectivity measurements.
