Massimiliano Di Ventra

Atomic-Scale Dynamics of the Formation and Dissolution of Carbon Clusters in SiO2

Oxidation of SiC produces SiO(2) while CO is released. A reoxidation step at lower temperatures is, however, necessary to produce high-quality SiO(2). This step is believed to cleanse the oxide of residual C without further oxidation of the SiC substrate. We report first-principles calculations that describe the nucleation and growth of O-deficient C clusters in SiO(2) under oxidation conditions, fed by the production of CO at the advancing interface, and their gradual dissolution by the supply of O under reoxidation conditions. We predict that both CO and CO(2) are released during both steps.

Molecular electronics by the numbers

Abstract The paper gives an overview of recent work by the authors on first-principles, parameter-free calculations of electronic transport in molecules in the context of experimental measurements of current–voltage ( I – V ) characteristics of several molecules by Reed et al. The results show that the shape of I – V characteristics is determined by the electronic structure of the molecule in the presence of the external voltage whereas the absolute magnitude of the current is determined by the chemistry of individual atoms at the contacts. A three-terminal device has been modeled, showing gain. Finally, recent data that show large negative differential resistance and a peak that shifts substantially as a function of temperature have been accounted for.

First-principles simulations of molecular electronics.

Abstract: This paper gives an overview of recent work by the authors in first‐principles, parameter‐free calculations of electronic transport in molecules in the context of experimental measurements of current‐voltage (I‐V) characteristics of several molecules by Reed et al. The results show that the shape of I‐V characteristics is determined by the electronic structure of the molecule in the presence of the external voltage, whereas the absolute magnitude of the current is determined by the chemistry of individual atoms at the contacts. A three‐terminal device has been simulated, showing gain. Finally, recent data that show large negative differential resistance and a peak that shifts substantially as a function of temperature have been accounted for in terms of rotations of ligands attached to the main molecule, a phenomenon that is not present in semiconductor nanostructures.