Energetics of oxygen adsorption and incorporation at InN polar surface: A first‐principles study

Abstract

AbstractFirst principles calculations are performed to study the adsorption and incorporation of oxygen at InN polar surfaces as a function of oxygen coverage. We find that the adsorption of oxygen at InN surfaces is higher on the N‐polar than on In‐polar. The calculations show that for the low coverage regime (x ≤ 0.5 ML) both orientations are active towards the adsorption of oxygen; this implies that the reaction between the O atoms and the surface is strongly exothermic. As the coverage of O exceeds 0.5 ML a large difference in adsorption energies, of almost 2.5 eV, is observed between (0001) and (000$ \bar 1 $) surfaces indicating that the (000$ \bar 1 $) surface is more active towards oxygen adsorption than the (0001) surface. The high coverage of oxygen changes the surface structure of InN due to the difference in binding energy (O‐In bonds are stronger than In‐N ones). This result shows explicitly that the formation of In adlayer is disturbed by the O adsorption. Concerning the energetics of O incorporation our results show that it is more favourable for O to substitute a N atom in one of the top layers near the surface than in bulk, indicating that there is a strong tendency for O to reside at the surface rather than in subsurface layers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)