The application of a new scheme for engineering Si(111) substrates so as to obtain high-quality GaN layers was reported. An ion-implanted defective layer was formed in the Si substrate that partially isolated, crystallographically and mechanically, the III-nitride layer and the Si substrate. This resulted in a reduction in strain in the nitride film. Nitrogen ion implantation energies of 60 to 75keV to doses of 1016 to 2 x 1016/cm2 were applied to AlN buffer layers, 55nm-thick, grown onto Si(111). The experimental results revealed an increase in the crack separation of over 1mm for 2µm-thick GaN film grown onto implanted 55nm AlN/Si complex substrates as seen by optical microscopy. The GaN films grown onto implanted AlN/Si substrates had a smoother surface morphology (rms roughness of 0.41nm) as compared to those grown onto non-implanted AlN/Si substrates (rms roughness of 1.50nm). The results of etch-pit density and X-ray diffraction measurements revealed a significant reduction in the dislocations in III-nitride layers. The data revealed a strong dependence of GaN quality upon the implantation conditions.

Reduction of Strain and Dislocation Defects in GaN Layers Grown on Si Substrate by MOCVD Using a Substrate Defect Engineering Technique. M.Jamil, E.Irissou, J.R.Grandusky, V.Jindal, F.Shahedipour-Sandvik: Physica Status Solidi C, 2006, 3[6], 1787-91