Phase diagram of III-Nitride ternary alloys
- Density functional theory (DFT) total energy and force calculations are employed to conduct an exhaustive ground-state search and set up a Cluster-Expansion (CE) Hamiltonian.
- Canonical as well as grand canonical Monte Carlo simulations have been employed to derive the phase diagram of bulk InGaN alloys biaxially strained to GaN.
In contrast to the wide-held belief that these alloys can be described by a simple regular solution model with a large miscibility gap, this phase diagram exhibits a rich set of hitherto unknown chemically ordered phases at various stoichiometries. The mechanism that dominates the formation of these ordered phases is efficient strain accommodation on the atomic scale . Furthermore, for the technologically important composition of x=25-35% ordered domains which have a √3×√3 in the basal plane pattern are found to be stable at temperatures below 700 K.