Current-induced organic molecule-silicon bond breaking: consequences for molecular devices

The current carrying capacity of individual organic molecules covalently bound to silicon has been studied. Adsorbates consisting exclusively of saturated C-C bonds were found to be entirely stable whereas adsorbates containing pi bonds could be controllably dislodged under modest conditions. The pi bonds act as a chromophore, taking energy from a scattered electron, energy that can be selectively channeled into Si-C bond breaking. The class of adsorbates that are dislodged is closely related to unsaturated molecules widely investigated for enhanced molecular wire character. It is predicted that molecular devices containing such molecules will fail when operated. Measures to avoid current-induced bond breaking are described. New processes based upon the controlled bond breaking phenomenon are suggested. (C) 2000 Elsevier Science B.V. All rights reserved.