HREM study of stacking faults in GaN layers grown over sapphire substrate

Epitaxial GaN layers grown on sapphire contain a very large density of defe cts (threading dislocations, stacking faults, inversion domain boundaries.. ..). Among these defects, we have performed the analysis of the basal stack ing faults by high resolution transmission electron microscopy. Two faults, I-1 and I-2, were identified. The formation of the I-1 fault is based on t he climb-dissociation process of the 1/3(11-20) or of the [0001] perfect di slocations whereas the I fault is due to the shear of the structure leading to a partial dislocation loop.