Critical concentration for the doping-induced metal-nonmetal transition in cubic and hexagonal GaN

The critical concentration for the metal-nonmetal transition has been calculated for n-type and p-type GaN. Both cubic and hexagonal structures of GaN have been considered. Three different computational methods have been utilized: the first is the original Mott model, the second is an extended Mott-Hubbard model, and the third method is based on total energy of the metallic and the nonmetallic phases. All three methods show a similar value of the critical concentration, about 10(18) and 10(20) cm(-3) for n-type and p-type doped materials, respectively. (C) 2002 American Institute of Physics.