Resonant tunneling of electrons through a single self-assembled InAs quantum dot probed via a novel overlayed quantum dot electrode

Abstract

The resonant tunneling process of electrons through a single self-assembled InAs quantum dot (QD) has been studied by conductive-tip atomic force microscopy. The unique structure employed here consists of two layers of InAs QDs, which are separated by 5-nm-thick undoped GaAs layer. The conductive tip is placed in contact with the surface InAs QD which functions as a nano-sized electrode to measure the flow of electrons from the n +-GaAs substrate via a buried QD. A conductance structure attributed to resonant electron tunneling through the quantized level of QD is observed in the current–voltage characteristics. The resonant voltage is larger than the usual flat band voltage, indicative of a considerable voltage loss caused by the Fermi level pinning around the nano-sized electrode.