Doping of homoepitaxial GaN layers

Gallium nitride doped with oxygen (unintentionally), silicon and magnesium was grown by metalorganic chemical vapor deposition on the conductive singl e crystals of GaN grown at high hydrostatic pressure. The layers were exami ned using X-ray diffraction, photoluminescence and far-infrared reflectivit y. It was found that the incorporation of silicon depends on the side used for deposition. For the two Si-doped layers grown in the same run, the one grown on the (00.1) side (gallium-terminated) had always smaller free elect ron concentration with respect to the (00.1) side (nitrogen-terminated). Th is conclusion could be drawn from the lattice expansion by free electrons, the photoluminescence peak shift by Burstein-Moss effect and the position o f plasma edge in far-infrared reflectivity.