Spontaneous S–Si bonding of alkanethiols to Si(111)–H: towards Si–molecule–Si circuits
Chandramalika R. Peiris, Simone Ciampi, Essam M. Dief, Jinyang Zhang, P.J. Canfield, Anton P. Le Brun, Daniel S. Kosov, Jeffrey R. Reimers, Nadim Darwish
Abstract
would normally oxidize the silicon and hence reaction conditions such as these have been strenuously avoided in the past. The surface coverage on Si(111)-H is measured to be very high, 75% of a full monolayer, with density-functional theory calculations used to profile spontaneous reaction mechanisms. The impact of the Si-S chemistry in single-molecule electronics is demonstrated using STM-junction approaches by forming Si-hexanedithiol-Si junctions. Si-S contacts result in single-molecule wires that are mechanically stable, with an average lifetime at room temperature of 2.7 s, which is five folds higher than that reported for conventional molecular junctions formed between gold electrodes. The enhanced "ON" lifetime of this single-molecule circuit enables previously inaccessible electrical measurements on single molecules.