Tunneling transport in devices with semiconducting leads

TL;DR

This paper extends the theory of tunneling transport to finite temperatures for devices with semiconducting leads, applying it to molecular systems and revealing that decay constants depend on band edges rather than Fermi level.

Contribution

It introduces a finite-temperature extension of tunneling transport theory applicable to semiconducting leads and provides insights into decay constants and transport channels in molecular devices.

Findings

Decay constant depends on band edges, not Fermi level.

Qualitative agreement with experimental data.

Mapping of evanescent transport channels provides physical insight.

Abstract

This paper extends the modern theory of tunneling transport to finite temperatures. The extension enables applications to molecular electronic devices connected to semiconducting leads. The paper presents an application of the theory to molecular devices made of alkyl chains connected to silicon nano-wires, mapping their transport characteristics as functions of temperature and alkyl chain's length. Based on these calculations and on the analytic theory, it is found that the tunneling decay constant is determined not by the Fermi level, but by the edge of the valence or conductance band, whichever is closer to the Fermi level. Further insight is provided by mapping the evanescent transport channels of the alkyl chains and few other physical quantities appearing in the analytic formula for conductance. A good qualitative agreement with the experimental data is obtained.