The dependence of inelastic electron tunneling on junction roughness

We have made a series of Al-Al2O3-benzoic acid-Pb inelastic electron tunneling spectroscopy (IETS) junctions on substrates roughened by varying thicknesses of CaF2. The vibrational peaks due to the molecular monolayer of benzoic acid disappear as the substrates are made rougher. We speculate on the cause of this disappearance. © 1983.