Initial stages of III-nitride growth

First-principles calculations are performed to investigate the adsorption b ehavior of group-III atoms and nitrogen on group-III-nitride(111) surfaces. We focus on one to three layers of cations on BN, AlN, GaN, and InN and co mpare their surface energies with that of the nitrogen-covered and clean su rface. The resulting surface phase diagrams indicate a preference for epita xial growth under cation-rich conditions after deposition of metal overlaye rs. This tendency, clearly pronounced for InN and GaN, is weakened for AlN and BN where lower III/V ratios are favorable. (C) 1999 American Institute of Physics. [S0003-6951(99)03025-9].