The effect of Si doping upon wurtzite-type GaN layers which had been grown, by means of molecular beam epitaxy, on AlN-buffered (111) Si substrates was studied. The planar defect density in the as-grown GaN layer increased strongly with Si doping. The dislocation density at the free surface of GaN decreased significantly when the Si doping exceeded a critical value. The Si doping affected the misorientation of the sub-grains that constituted the mosaic structure of GaN. The increase, with Si doping, of the planar defect density and out-of-plane misorientation angles of the GaN sub-grains explained the decrease in the number of dislocations that reached the free surface of GaN.

The Effect of Si Doping on the Defect Structure of GaN/AlN/Si(111) S.I.Molina, A.M.Sánchez, F.J.Pacheco, R.García, M.A.Sánchez-García, F.J.Sánchez, E.Calleja: Applied Physics Letters, 1999, 74[22], 3362-4