Electron transport through a silicon-germanium double quantum dot at 40mK

Abstract

Low-temperature electron transport measurements have been performed on a trench-isolated silicon-germanium (SiGe) double quantum dot. Transport through the quantum-dot structure was via Coulomb blockade, allowing the control of single electrons. As the drain-source bias across the double dot was increased, it was found that the Coulomb peak broadened and a second smaller peak developed in proportion to the source-drain voltage. The structure behaved predominately as a single dot but the confinement potential was not simply a single well. Additionally, two extra peaks appeared on the Coulomb blockade plots at a fixed charge configuration. The transport mechanisms assigned to the peaks were via single electron tunneling through excited states and second-order tunneling via a second smaller dot formed in series with the main dot.