A thermal equilibrium method was used to calculate the background carrier concentration that was related to intrinsic defects in an ideal GaN crystal. The results showed that the N vacancy concentration did not exceed 2 x 1017/cm3 in samples which had been grown at temperatures ranging from 800 to 1500K. It was concluded that the N vacancy was one of major sources of carriers when the carrier concentration was less than 2 x 1017/cm3, but that the major sources were other defects when the carrier concentration was greater than 2 x 1017/cm3.

G.Y.Zhang, Y.Z.Tong, Z.J.Yang, S.X.Jin, J.Li, Z.Z.Gan: Applied Physics Letters, 1997, 71[23], 3376-8