GaN templates grown by the metal organic chemical vapour deposition method were etched in a defect-selective molten salts eutectic and were subsequently overgrown by a GaN layer using the hydride vapour phase epitaxy method. Optimized conditions of etching and of hydride vapor phase epitaxy growth processes resulted in a significant reduction of the dislocation density. Local areas virtually free of dislocations were obtained on ∼ 50% of the surface, while the average dislocation density was reduced from 3 x 109/cm2 in the template to about 2 x 107/cm2 in the hydride vapor phase epitaxially-grown GaN layer. A model was developed to explain the mechanism of reduction of the dislocation density during the overgrowth process. The model was confirmed by the photo-etching of cleaved layers.

Reduction of Dislocation Density in Epitaxial GaN Layers by Overgrowth of Defect-Related Etch Pits. J.L.Weyher, H.Ashraf, P.R.Hageman: Applied Physics Letters, 2009, 95[3], 031913