Coulomb blockade and Kondo effect in a few-electron silicon/silicon-germanium quantum dot

TL;DR

This study investigates electron transport in silicon/silicon-germanium quantum dots at cryogenic temperatures, revealing Coulomb blockade, the Kondo effect, and Fano resonance transitions as the coupling to leads varies.

Contribution

It demonstrates the coexistence of Coulomb blockade and Kondo effect in silicon-based quantum dots, with detailed analysis of their magnetic field dependence and Fano resonance behavior.

Findings

Observation of Coulomb blockade in silicon/silicon-germanium quantum dots.

Detection of Kondo effect with magnetic field splitting.

Transition from Coulomb blockade to Fano resonance peaks.

Abstract

Transport measurements at cryogenic temperatures through a few electron top gated quantum dot fabricated in a silicon/silicon-germanium heterostructure are reported. Variations in gate voltage induce a transition from an isolated dot toward a dot strongly coupled to the leads. In addition to Coulomb blockade, when the dot is strongly coupled to the leads, we observe the appearance of a zero bias conductance peak due to the Kondo effect. The Kondo peak splits in a magnetic field, and the splitting scales linearly with the applied field. We also observe a transition from pure Coulomb blockade to peaks with a Fano lineshape.