Electronic Characteristics and Charge Transport Mechanisms for Large Area Aromatic Molecular Junctions

Abstract

This paper reports the electron transport characteristics of carbon/molecule/Cu molecular junctions, where aromatic molecules (azobenzene or AB and nitroazobenzene or NAB) are employed as the molecular component. It is shown that these devices can be made with high yield (>90%), display excellent reproducibility, and can withstand at least 1.5 × 109 potential cycles and temperatures of at least 180 °C. Transport mechanisms are investigated by analysis of current density/voltage (J−V) curves as a function of the molecular layer thickness and temperature. Results show that J decreases exponentially with thickness, giving a measured value for the low-bias attenuation factor (β) of 2.5 ± 0.1 nm−1 for AB and NAB. In addition, it is shown that transport is not thermally activated over a wide range of temperatures (5−450 K) and that the appearance of a thermally “activated” region at higher temperatures can be accounted for by the effect of temperature on the distribution of electrons around the Fermi level of t...