Keele Research Repository

We studied the adsorption of 7,7,8,8-tetracyanoquinodimethane (TCNQ) on the Si(111)√7×√3 In surface, a known surface superconductor. Scanning tunneling microscopy shows the development of a surface-confined metal–organic network (SMON) where TCNQ molecules coordinate with indium atoms from the underlyin g √7×√3 reconstruction. The formation of the SMON causes a surface structural phase transition from the √7×√3 reconstruction to a previously unknown 5 × 5 reconstruction of the Si(111)–In surface. Scanning tunneling spectroscopy measurements indicate that the 5 × 5 reconstruction has a stronger insulating character than the √7×√3 reconstruction. Density-functional-theory calculations are used to evaluate the atomic arrangement and stability of the 5 × 5 and √7×√3 reconstructions as a function of In coverage, and suggest that the structural phase transition is driven by a slight reduction of the In coverage, caused by the incorporation of indium atoms into the SMON.