title: Conductive molecular silicon.
abstract: Bulk silicon, the bedrock of information technology, consists of the deceptively simple electronic structure of just Si-Si σ bonds. Diamond has the same lattice structure as silicon, yet the two materials have dramatically different electronic properties. Here we report the specific synthesis and electrical characterization of a class of molecules, oligosilanes, that contain strongly interacting Si-Si σ bonds, the essential components of the bulk semiconductor. We used the scanning tunneling microscope-based break-junction technique to compare the single-molecule conductance of these oligosilanes to those of alkanes. We found that the molecular conductance decreases exponentially with increasing chain length with a decay constant β = 0.27 ± 0.01 Å(-1), comparable to that of a conjugated chain of C═C π bonds. This result demonstrates the profound implications of σ conjugation for the conductivity of silicon.
authors.affiliation: Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Rebekka S
authors.initials: RS
authors.lastname: Klausen
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Widawsky
authors.forename: Michael L
authors.initials: ML
authors.lastname: Steigerwald
authors.forename: Latha
authors.initials: L
authors.lastname: Venkataraman
authors.forename: Colin
authors.initials: C
authors.lastname: Nuckolls