p and n type doping of cubic GaN on SiC (001)

n-type doping with Si and p-type doping with Mg are reported for cubic GaN grown by molecular beam epitaxy (MBE) on cubic SiC(001). Mg incorporation as high as 1×1019 cm−3 has been reached at low growth temperatures. However, no correlation is found between the hole concentration and Mg concentration, probably due to deep levels induced by the stacking faults and the residual doping present in the layer, as revealed by the deep optical transition which dominates the photoluminescence (PL) spectra. In contrast, n-type doped samples with Si are much better controlled, with a maximum value of 5×1019 cm−3 for the free electron concentration, and with a clear donor signature in their PL spectra.