Metal modulation epitaxy growth for extremely high hole concentrations above 1019cm−3 in GaN

The free hole carriers in GaN have been limited to concentrations in the low 1018cm−3 range due to the deep activation energy, lower solubility, and compensation from defects, therefore, limiting doping efficiency to about 1%. Herein, we report an enhanced doping efficiency up to ∼10% in GaN by a periodic doping, metal modulation epitaxy growth technique. The hole concentrations grown by periodically modulating Ga atoms and Mg dopants were over ∼1.5×1019cm−3.