The use of a new scheme of substrate engineering of Si(111) to obtain high-quality GaN layers was reported. An ion implanted defective layer was formed in the Si substrate that partially, crystallographically and mechanically isolates the III-Nitride layer and Si substrate which results in reduction of strain in the Nitride film. Nitrogen ion implantation energies of 60 to 75keV and ion doses of 1016 to 2 x 1016/cm2 were applied to AlN buffer layers, 55nm thick, grown on Si (111). The experimental results showed an increase in the crack separation of over 1mm for 2µm thick GaN film grown on implanted 55nm AlN/Si complex substrate as seen under optical microscope. Moreover the GaN films grown on implanted AlN/Si substrate showed smoother surface morphology (RMS roughness of 0.41nm) as compared to that grown on non-implanted AlN/Si substrates (RMS roughness of 1.50nm). Results of etch pit density and X-ray diffraction measurements showed significant reduction in 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