Metal modulation epitaxy growth for extremely high hole concentrations above 10{sup 19} cm{sup -3} in GaN

The free hole carriers in GaN have been limited to concentrations in the low 10{sup 18} cm{sup -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 {approx}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 {approx}1.5x10{sup 19} cm{sup -3}.