Electron mobility, as limited by N-vacancy scattering was used to evaluate the quality of n-type samples which had been grown by means of metal-organic vapour phase epitaxy. The N-vacancy scattering potential which was used in the mobility calculations had to satisfy 2 requirements. One was that the potential should be spatially short-ranged. The other was that it should be finite, and not diverge at the vacancy core. A square-well potential was used to calculate the mobility because it satisfied these 2 requirements and also simplified the calculations. As a result, the estimated mobility exhibited an inverse square-root temperature dependence, and was very sensitive to the potential-well width. After introducing N-vacancy scattering, the best fit between calculated and experimental results was obtained for high-quality samples. It was found that the measured mobility was dominated by ion impurity and dislocation scattering at low temperatures, but was dominated by optical phonon and N-vacancy scattering at high temperatures.

Nitrogen Vacancy Scattering in n-GaN Grown by Metal-Organic Vapor Phase Epitaxy Q.S.Zhu, N.Sawaki: Applied Physics Letters, 2000, 76[12], 1594-6