Theoretical study of segregation kinetics of indium in indium gallium nitride and magnesium in magnesium-gallium nitride grown by molecular beam epitaxy

A rate equation model including all physically relevant surface processes is developed for the study of In segregation in InGaN and Mg segregation in Mg-GaN MBE growth. In InGaN growth, the simulations were carried for a variety of growth conditions spanning the growth parameter space: substrate temperature in the range of 500--700°C: Ga flux in the range of 1.17--8.98 nm/min: In flux in the range of 0.39--28.74 nm/min and N flux in the range of 4.7--12 nm/min. Results of In incorporation obtained from simulations are within 1% agreement with the experiments reported in the literature. In segregation is found to be negligible below 580°C . Above 640°C, the segregation dominates the kinetics. This temperature dependence is found to be independent of the fluxes. In Mg-GaN growth, simulations were carried for various growth temperatures in the range of 600--750°C with constant flux rates of Mg, Ga and N. For the given flux rates, it is found that Mg segregates to the surface with the increase in temperature. Above 750°C a dopant depleted zone is formed below the surface layer. Results obtained from simulations are in good qualitative agreement with the experimental data.