The structural characteristics of GaN films grown on sapphire substrates by molecular beam epitaxy have been investigated using high-resolution synchrotron x-ray diffraction and electron microscopy. We find remarkable correspondence between the in-plane structural order (coherence length and mosaic spread) and the electrical and optical properties. Contrary to common belief, our observations show unequivocally that the out-of-plane structural features, which are considerably better developed than the in-plane counterparts, cannot be used for determining the material quality with respect to their optical and electrical activity. In particular, the (00l) mosaic spread is not a good indicator of film quality.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)