The effect of Mn ions on the growth of cubic GaN

We perform first-principles pseudopotential calculations to investigate the effect of Mn delta-doping on the stability of the zinc-blende and wurtzite structures in GaN. In bulk GaN, it is possible for the zinc-blende structure to become a stable phase againt the wurtzite one with increasing the concentration of the delta-doped Mn ions. On GaN surfaces, it costs very high energies to form inversion domains with a Mn exposure because the Mn-N bond is not strong enough to stabilize the inverted structures. In the initial growth of GaN, we also examine the formation of stacking faults by the Mn delta-doping, which generate cubic bonds, and find that the stacking faults easily occur on the Ga-polar surface rather than on the N-polar one. On the Ga-polar surface, the Mn ions tend to remain on the surface than in the bulk region, suggesting that these ions act as a surfactant.