Identifying contact effects in electronic conduction through buckyballs on silicon

TL;DR

This paper develops a theoretical model combining density functional theory and NEGF to analyze how contact microstructure affects electronic conduction through buckyballs on silicon, explaining experimental conductance variations.

Contribution

It introduces a coupled DFT-NEGF approach to quantitatively link contact microstructure with conductance features in buckyball-silicon systems.

Findings

Contact microstructure influences conductance peak positions and shapes.

Variations in probe separation affect conductance peak amplitudes.

The model explains experimental conductance-voltage characteristics.

Abstract

We present a theory of current conduction through buckyball(C60) molecules on silicon by coupling a density functional treatment of the molecular levels embedded in silicon with a non-equilibrium Green's function (NEGF) treatment of quantum transport. Several experimental variations in conductance-voltage(G-V) characteristics are quantitatively accounted for by varying the detailed molecule-silicon bonding geometries. We identify how variations in contact surface microstructure influence the number, positions and shapes of the conductance peaks, while varying separations of the scanning probe from the molecules influence their peak amplitudes.