Incorporation of beryllium on the clean and indium-terminated GaN(0001) surface

First-principles calculations of the energetics of Be incorporation in various sites on clean and indium-terminated GaN(0001) are presented. On the clean Ga-rich surface the Be atom prefers a surface substitutional Ga site over a near-surface interstitial site by about 1.0 eV, thus suggesting that interstitial concentrations could be suppressed near the surface during growth. Calculations for In-terminated surfaces suggest that it is possible to enhance incorporation of Be on the Ga site by performing the growth under conditions in which Be compensates compressive stress resulting from In incorporation.