Undoped p-type GaN1–xSbx alloys: Effects of annealing

We report p-type behavior for undoped GaN1–xSbx alloys with x ≥ 0.06 grown by molecular beam epitaxy at low temperatures (≤400 °C). Rapid thermal annealing of the GaN1–xSbx films at temperatures >400 °C is shown to generate hole concentrations greater than 1019 cm−3, an order of magnitude higher than typical p-type GaN achieved by Mg doping. The p-type conductivity is attributed to a large upward shift of the valence band edge resulting from the band anticrossing interaction between localized Sb levels and extended states of the host matrix.