Modeling the compositional instability in wurtzite Ga_1−xIn_xN

The paper deals with multiscale modeling of the minor component ordering in wurtzite Ga_1−xIn_xN (x<0.5) alloys. The treatment combines the total-energy density-functional calculations of the metal atom interaction parameters and the atomistic description of the alloy decomposition using lattice kinetic Monte Carlo. It is demonstrated that the phase decomposition patterns in wurzite GaInN are very sensitive to the interplay of metal atom interactions at several interatomic distances (at least to the fourth nearest neighbors) on the cation sublattice. Variation of the metal interaction energies within reasonable limits resulted in pronouncedly different relaxation patterns (linear or wall ordering of In and Ga atoms along c-axis, planar ordering parallel to basal plane, spinodal decomposition). The high sensitivity of the GaInN decomposition to relatively small variations of the metal interaction energies could be the main reason for the experimentally observed versatility of the alloy decomposition patterns and their sensitivity to the particular experimental conditions.