Effects of broadening and electron overheating in tunnel structures based on metallic clusters

TL;DR

This paper investigates how energy level broadening and electron overheating affect the current-voltage characteristics of metallic cluster-based tunnel structures, providing a calculation scheme and estimating these effects in gold clusters.

Contribution

It introduces a calculation scheme for broadening effects in one-dimensional structures and estimates electron overheating in gold clusters, explaining experimental smoothing of I-V curves.

Findings

Broadening and overheating cause smoothing of I-V curves.

Effective electron temperature depends on bias voltage.

The effects explain experimental observations at low temperatures.

Abstract

We study the influence of energy levels broadening and electron subsystem overheating in island electrode (cluster) on current-voltage characteristics of three-electrode structure. A calculation scheme for broadening effect in one-dimensional case is suggested. Estimation of broadening is performed for electron levels in disc-like and spherical gold clusters. Within the two-temperature model of metallic cluster and by using a size dependence of the Debye frequency the effective electron temperature as a function of bias voltage is found approximately. We suggest that the effects of broadening and electron overheating are responsible for the strong smoothing of current-voltage curves, which is observed experimentally at low temperatures in structures based on clusters consisting of accountable number of atoms.