Detection of Single Electron Charging in an Individual InAs Quantum Dot by Noncontact Atomic Force Microscopy

TL;DR

This paper demonstrates the detection of single electron charging in an individual InAs quantum dot using noncontact atomic force microscopy, revealing Coulomb blockade effects through frequency shift and energy dissipation measurements.

Contribution

It introduces a novel force-based method to observe single electron tunneling in quantum dots with AFM, providing a new approach to study quantum charge phenomena.

Findings

Observation of discrete jumps in frequency shift and dissipation peaks

Correlation of these jumps with single electron tunneling events

Validation of Coulomb blockade model through force measurements

Abstract

Single electron charging in an individual InAs quantum dot was observed by electrostatic force measurements with an atomic force microscope (AFM). The resonant frequency shift and the dissipated energy of an oscillating AFM cantilever were measured as a function of the tip-back electrode voltage and the resulting spectra show distinct jumps when the tip was positioned above the dot. The observed jumps in the frequency shift, with corresponding peaks in dissipation, are attributed to a single electron tunneling between the dot and the back electrode governed by Coulomb blockade effect, and are consistent with a model based on the free energy of the system. The observed phenomenon may be regarded as the ``force version'' of the Coulomb blockade effect.