Electron tunneling spectroscopy—External doping with organic molecules

Abstract

We report the observation of inelastic electron tunneling spectra of molecules introduced into completely fabricated tunnel junctions. By using an external doping method several kinds of molecules have been introduced into Al–Al oxide–Pb diodes yielding strong spectra characteristic of the particular molecules. This technique is a new way of detecting and studying molecules interacting with surfaces. The high sensitivity and greater simplicity of this method increases possible applications of tunneling spectroscopy.