Single-molecule transistors: Electron transfer in the solid state

Abstract

Single-molecule transistors (SMTs) incorporating individual small molecules are unique tools for examining the fundamental physics and chemistry of electronic transport in molecular systems at the single nanometer scale. We describe the fabrication and characterization of such devices, and the synthesis and surface attachment chemistry of novel transition metal complexes that have been incorporated into such SMTs. We present gate-modulated inelastic electron tunneling vibrational spectroscopy of single molecules, strong Kondo physics (T K $ 75 K) as evidence of excellent molecule/electrode electronic coupling, and a demonstration that covalent attachment chemistry can produce SMTs that survive repeated thermal cycling to room temperature. We conclude with a look ahead at the prospects for these nanoscale systems.

Coulomb repulsion effect in two-electron nonadiabatic tunneling through a one-level redox molecule

“…Other potential target systems include bipyridine-and terpyridine-based transition metal complexes of ruthenium, osmium, and perhaps other transition metal complexes stable in several oxidation states. 18,19,61,62 Oscomplexes exhibit strong electrochemical tunneling spectroscopy 18,19 and are accessible in the II/III/IV oxidation states, 63 and might particularly offer such a class. Polynuclear cluster complexes of other transition metals ͑Fe, Mn, V, Mo͒ might hold other clues.…”

Simultaneous Measurements of Electronic Conduction and Raman Response in Molecular Junctions

“…[30] In this paper we use these nanoscale gap structures to perform simultaneous measurements of electronic transport and SERS. In many previous papers [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] it has been established that conductance in such structures is dominated by roughly a molecular volume. The conductance as a function of time is observed to correlate strongly with the SERS signal in 11% of the junctions measured.…”

“…Our understanding of electronic conduction through single small molecules has grown dramatically in the last decade thanks to improved techniques, including mechanical break junctions [1,2,3] single-molecule transistors (SMTs) [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19], nanoparticle dimers [20], noise characterization [21], and thermopower measurement [22]. A major complication in interpreting these experiments is the lack of local imaging or spectroscopic tools that can assess the environment and presence of the molecule of interest.…”

“…Electromigration has been used extensively to prepare electrodes for single-molecule conduction measurements, with typical yields of ∼ 10-20% for tunneling gaps inferred to contain individual molecules (based on statistics on thousands of junctions) [4,5,6,8,9,10,11,12,13,14,15,17,18]. Each gap is electromigrated with an automated procedure to form an atomic-scale constriction with a resistance of ∼3 kΩ, which is then allowed to break spontaneously [36].…”

Molecular Electronics: A Review of Experimental Results

“…Using this technique, the vibrational spectra of oligophenylenevinylene (OPV) could be identified, indicating that the CB structure indeed stems from transport through the molecule [21]. Other molecular properties like the Kondo resonances, which occur due to unpaired spins coupling to the electrons in the metallic leads, were identified as well in C 60 molecules [22] and OPV [23]. C 60 molecules also showed the presence of mechanical resonances [24].…”