The structure of Si(111) above the 7×7⇆‘‘1×1clzquo transition temperature has been compared with that of the laser-quenched surface using low-energy electron diffraction. Pronounced half-order features, similar to those observed on Ge(111), are observed on the laser-quenched surface. No preferential ordering of the half-order features occurs on vicinal surfaces misoriented by 4° and 6° from the (111) surface suggesting that the features arise from a local 2×2 rather than 2×1 structure. Half-order features also occur on the equilibrium surface above 870?deC; however they are much broader and weaker. The doubled-periodicity components of the surface partially orders during laser quenching.

• Received 8 December 1986

DOI:https://doi.org/10.1103/PhysRevB.35.4155