Co-adsorption patterns of NH3 on Si(0 0 1): Comment on “The ordering of the adsorbed NH3 molecules across the Si dimer rows on the Si(0 0 1) surface”

In their paper, Chung et al. [O.N. Chung, H. Kim, J.-Y. Koo, S. Chung, Surf. Sci. Lett. 602 (2008) L69.] discuss the interaction of adsorbing ammonia fragments on the Si(0 0 1) surface. We suggest that they have failed adequately to explain the correlations they observe. Using a different interpretation of the STM appearance of NH2 fragments gives strong support for cross-dimer row interactions mediated by hydrogen bonds between NH2 groups which is not seen with their present interpretation.