To obtain a deeper insight into the mechanism of defect formation in a-plane GaN the defect nature in such films grown by metal-organic vapor phase epitaxy and hydride vapor phase epitaxy was investigated by means of transmission electron microscopy. The films exhibited, beside the frequently found basal plane stacking faults and threading dislocations, prismatic stacking faults originating at the film/substrate interface and facetted voids. The density of basal plane stacking fault was about 105/cm and the density of partial dislocations was in the range of 1010/cm2, accordingly. Using selected area diffraction the epitaxial relationship between film and layer was determined. Based on these findings the impact of lattice mismatch on the observed defect characteristic was discussed.

Defect Structure of a-Plane GaN Grown by Hydride and Metal-Organic Vapor Phase Epitaxy on r-Plane Sapphire. R.Kröger, T.Paskova, B.Monemar, S.Figge, D.Hommel, A.Rosenauer: Physica Status Solidi C, 2007, 4[7], 2564-7