Electron tunnelling in self-assembled monolayers

A review on the mechanisms and characterization methods of electronic transport through self-assembled monolayers (SAMs) is presented. Using SAMs of alkanethiols in a nanometre scale device structure, tunnelling is unambiguously demonstrated as the main intrinsic conduction mechanism for defect-free large bandgap SAMs, exhibiting well-known temperature and length dependences. Inelastic electron tunnelling spectroscopy exhibits clear vibrational modes of the molecules in the device, presenting direct evidence of the presence of molecules in the device. 1 Current address: Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. 2 Current address: Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, 500-712, Korea. 3 Author to whom any correspondence should be addressed. 0034-4885/05/030523+22$90.00 © 2005 IOP Publishing Ltd Printed in the UK 523