Ammonia adsorption on Cl/Si(0 0 1): First-principles calculations

Motivated by recent experiments [C.C. Finstad, A.G. Thorsness, A.J. Muscat, Surf. Sci. 600 (2006) 3363], the interaction between ammonia and the Cl-terminated Si(0 0 1) surface is studied using density functional theory (DFT). The reaction NH3 (gas) + Si(0 0 1):Cl → Si(0 0 1):NH2 + HCl (gas) is endothermic, even if temperature effects are included in the calculation. We find that the formation of ionic bonds between surface-bonded NH3+ and nearby Cl− rather than the desorption of HCl corresponds to a local energy minimum.