Spatially Resolved Characterization of Microstructure, Defects and Tilts in GaN Layers Grown on Si(111) Substrates by Maskless Cantilever Epitaxy

Abstract

ABSTRACTThe spatially resolved distribution of strain, misfit and threading dislocations, and crystallographic orientation in uncoalesced GaN layers grown on Si(111) substrates by maskless cantilever epitaxy was studied by white-beam Laue x-ray microdiffraction, scanning electron microscopy, and orientation imaging microscopy. Tilt boundaries formed at the column/wing interface with the misorientation strongly depending on the growth conditions. A depth-dependent deviatoric strain gradient is found in the GaN. Types and density of misfit dislocations as well as their arrangement within different dislocation arrays was quantified. The results are discussed with respect to the miscut of the Si(111) surface and misfit dislocations formed at the interface.