Stabilizing influence of double bonds on the Si(111)-(3×1) and Ge(111)-(3×1) surface reconstructions: new experimental evidence

We have obtained new real-space images of the filled dangling-bond states of the alkali-metal-induced (3×1) reconstruction of the Si(111) surface associated with recently proposed SiSi double-bond surface structures. Our new experimental evidence reveals significant subtle differences between this local bonding on Na/Si(111)-(3×1) and Na/Ge(111)-(3×1) which argues a strong case for the proposed ‘honeycomb chain-channel model’ but with a relaxation of a strict double-bond requirement, particularly on the germanium surface.