Nitrogen vacancy scattering in GaN grown by metal–organic vapor phase epitaxy

Abstract

Electron mobility limited by nitrogen vacancy scattering was taken into account to evaluate the quality of n-type GaN grown by metal–organic vapor phase epitaxy. Two assumptions were made for this potential for the nitrogen vacancy (1) it acts in a short range, and (2) does not diverge at the vacancy core. According to the above assumptions, a general expression to describe the scattering potential U(r)=−U 0 exp[−(r/β) n], (n=1,2,…,∞) was constructed, where β is the potential well width. The mobilities for n=1,2, and ∞ were calculated based on this equation, corresponding to the simple exponential, Gaussian and square well scattering potentials, respectively. In the limiting case of kβ≪1 (where k is the wave vector), all of the mobilities calculated for n=1,2, and ∞ showed a same result but different prefactor. Such difference was discussed in terms of the potential tail and was found that all of the calculated mobilities have T −1/2 temperature and β −6 well width dependences. A mobility taking account of a spatially complicate scattering potential was studied and the same temperature dependence was also found. A best fit between the calculated results and experimental data was obtained by taking account of the nitrogen vacancy scattering.