Microstructural evolution in a multiple composite layer of GaN on sapphire by organometallic vapor phase epitaxy

Abstract

Using cross-section transmission electron microscopy and grazing incidence x-ray diffraction measurements, this work investigates the defect reduction in a wurtize GaN thin film with a multiple composite layer grown by atmospheric-pressure organometallic vapor phase epitaxy on sapphire substrate. According to those results, the sequential composite layer can terminate most threading dislocations and only a few dislocations can be deeply propagated into the next epitaxial layer. Moreover, the multiple composite layer structure significantly reduces the density of threading dislocation generated from the GaN/Al2O3 interface.