High-quality GaN layers were grown onto Si(111) substrates, using optimized AlN buffer layers. A reduction in the lattice parameter, together with a red-shift in the photoluminescence emission, was observed with increasing Si doping. The dislocation density, as observed using plan-view transmission electron microscopy, also decreased by almost an order of magnitude (from 5.3 x 109 to 8 x 108/cm2) upon increasing the Si doping from 1.1 x 1017 to 6.0 x 1019/cm3.

MBE Growth of GaN and AlGaN Layers on Si(111) Substrates: Doping Effects. M.A.Sánchez-García, E.Calleja, F.B.Naranjo, F.J.Sánchez, F.Calle, E.Muñoz, A.M.Sánchez, F.J.Pacheco, S.I.Molina: Journal of Crystal Growth, 1999, 201-202, 415-8