Theoretical study of the composition pulling effect in InGaN metalorganic vapor-phase epitaxy growth

The composition pulling effect in metalorganic vapor-phase InGaN epitaxy was theoretically investigated by thermodynamic analysis. The excess energies of biaxial-strained In x Ga 1− x N were numerically calculated using empirical interatomic potentials considering different situations: (i) coherent growth on GaN(0001), (ii) coherent growth on In 0.2 Ga 0.8 N(0001), and (iii) bulk growth. Using the excess energies, the excess chemical potentials of InN and GaN alloys were computed. Our results show that compressive strain suppresses In incorporation, whereas tensile strain promotes it. Moreover, assuming chemical equilibrium, the relationship between the solid composition and the growth conditions was predicted. The results successfully reproduced the typical composition pulling effect.