The structure of the (001)(2 x 4) surface was deduced from a study of scanning tunnelling microscopic images that were obtained from metal-organic vapour phase epitaxially grown samples under ultra-high vacuum conditions. The scanning tunnelling microscopic images were compared with the results of first-principles calculations for models that were energetically most favourable under Ga-rich growth conditions. The comparison showed that the (001)-(2 x 4) surface unit cell consisted of a mixed Ga-P dimer on top of a complete Ga layer. This ruled out the Ga-Ga dimer model.

Clarification of the GaP(001)-(2 x 4) Ga-Rich Reconstruction by Scanning Tunnelling Microscopy and ab initio Theory. K.Lüdge, P.Vogt, O.Pulci, N.Esser, F.Bechstedt, W.Richter: Physical Review B, 2000, 62[16], 11046-9