Revealing Energy Level Structure of Individual Quantum Dots by Tunneling Rate Measured by Single-Electron Sensitive Electrostatic Force Spectroscopy

Antoine Roy-Gobeil , Yoichi Miyahara *, and Peter Grutter
Department of Physics, McGill University, 3600 rue University, Montreal, Quebec H3A2T8, Canada
Nano Lett., 2015, 15 (4), pp 2324–2328
DOI: 10.1021/nl504468a
Publication Date (Web): March 11, 2015

To my great pleasure, I got published in Nano Letters (impact factor of 13.592). A lot of hard work went into this and I would like to thank everybody that supported me in my work.

You can find a link to the PDF below in case you are outside of the paywall.


We present theoretical and experimental studies of the effect of the density of states of a quantum dot (QD) on the rate of single-electron tunneling that can be directly measured by electrostatic force microscopy (e-EFM) experiments. In e-EFM, the motion of a biased atomic force microscope cantilever tip modulates the charge state of a QD in the Coulomb blockade regime. The charge dynamics of the dot, which is detected through its back-action on the capacitavely coupled cantilever, depends on the tunneling rate of the QD to a back-electrode. The density of states of the QD can therefore be measured through its effect on the energy dependence of tunneling rate. We present experimental data on individual 5 nm colloidal gold nanoparticles that exhibit a near continuous density of state at 77 K. In contrast, our analysis of already published data on self-assembled InAs QDs at 4 K clearly reveals discrete degenerate energy levels.

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