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 (HVPE)

method. Optimized conditions of etching and of HVPE growth processes resulted

in a significant reduction of the dislocation density (DD). Local areas virtually free

of dislocations were obtained on ~50% of the surface, while the average DD was

reduced from 3 x 109cm−2 in the template to about 2 x 107cm−2 in the HVPE-grown

GaN layer. A model was developed to explain the mechanism of reduction of the

DD 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