Resonant tunneling of electrons through single self‐assembled InAs quantum dot at room temperature studied with conductive AFM tip

Abstract

Resonant tunneling of electrons through a quantum level in a self‐assembled InAs quantum dot (QD) has been measured by conductive atomic force microscopy (AFM) at room temperature. InAs QDs are embedded in a 3.4 nm‐thick AlAs layer, and capped with 8.3 nm‐thick GaAs layer on which surface InAs QDs are deposited as nano‐scale electrodes. Bringing the conductive AFM tip on the surface InAs QD which should be vertically aligned with a buried QD, a bias voltage is applied to the sample, and a current flowing via the buried QD is measured. Negative differential resistance attributed to electron resonant tunnelling through a quantized energy level in the buried QD is observed in the current‐voltage characteristics. The voltage loss by nano‐scale electrode and the dependence of resonance voltage on the size of the surface QD‐electrodes are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)