The effect of metal-molecule contacts in molecular junctions is studied based on the analysis of a statistically significant number of devices and a proposed multibarrier tunneling (MBT) model, where a metal-molecule-metal junction is divided into three individual barriers: a molecular-chain body and metal-molecule contacts on either side of molecule. Using the MBT model with the statistical analysis, we could derive and distinguish decay coefficients for contact barriers $({\beta }_1,{\beta }_2)$, contact-dependent and contact-independent decay coefficients (${\beta }_0$ vs ${\beta }_{\text{body}}$), and specific contact resistances in terms of different molecular length and different natures of metal-molecule contacts.

• Received 21 August 2007

DOI:https://doi.org/10.1103/PhysRevB.76.205320