Ordering phenomena and formation of nanostructures in InxGa1-xN layers coherently grown on GaN(0001)

We study the impact that local strain effects have on the spatial distribution of In in coherent In-x Ga1-x grown epitaxially on GaN(0001) using an effective crystal growth modeling technique that combines a semi-grandcanonical Monte Carlo simulation with an ab initio parametrized empirical force field. Our calculations show that In-x Ga1-x N epitaxial layers exhibit a strong tendency towards ordering, as highlighted by the formation of a vertical stack of the root 3 x root 3 patterned layers along the < c > direction. The ordering phenomena are identified as a key factor that determines lateral phase separation in In-x Ga1-x N epitaxial layers at the nanometer scale. Consequences of this nanophase separation for the enhanced radiative emission through carrier localization in InxGa1-xN of x < 1/3 are discussed.