Quantitative Model for the MBE-Growth of Ternary Nitrides

We report on a study of the growth of ternary AlGaN and InGaN by molecular beam epitaxy, leading to a quantitative model describing the alloy composition and growth rate as a function of group III fluxes, N flux and growth temperature. For low growth temperatures, the composition is exclusively determined by the different bond strengths between the group III elements and N, leading to a complete displacement of the more weakly bound species. The In loss from InGaN observed for typical growth conditions is caused by thermal decomposition of the growing layer with an activation energy between 3.5 and 3.8 eV depending on the In content.