Stacking fault energies in Si doped GaN: A first principles study

The variation of stacking fault energy in GaN as a function of silicon doping is calculated using density functional theory. It is found that the stacking fault energy reduces with increasing silicon concentration in agreement with experimental observations of higher stacking fault densities in Si doped GaN compared to undoped GaN. The result is explained in terms of a decrease in the magnitude of the Mulliken charges on the atoms as silicon is incorporated into the lattice and an increase in the overlap populations. We propose that Mulliken charges can be used to predict how any substitutional impurity will influence the stacking fault formation energy.