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Near-Equilibrium Measurement of Quantum Size Effects Using Kelvin Probe Force Microscopy

Abstract

In nanostructures such as thin films electron confinement results in the quantization of energy levels in the direction perpendicular to the film. The discretization of the energy levels leads to the oscillatory dependence of many properties on the film thickness due to quantum size effects. Pb on Si(111) is a specially interesting system because a particular relationship between the Pb atomic layer thickness and its Fermi wavelength leads to a periodicity of the oscillation of two atomic layers. Here, we demonstrate how the combination of scanning force microscopy (SFM) and Kelvin probe force microscopy (KPFM) provides a reliable method to monitor the quantum oscillations in the work function of Pb ultra-thin film nanostructures on Si(111). Unlike other techniques, with SFM/KPFM we directly address single Pb islands, determine their height while suppressing the influence of electrostatic forces, and, in addition, simultaneously evaluate their local work function by measurements close to equilibrium, without current-dependent and non-equilibrium effects. Our results evidence even-odd oscillations in the work function as a function of the film thickness that decay linearly with the film thickness, proving that this method provides direct and precise information on the quantum states.

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Publication details

The article was received on 16 Mar 2017, accepted on 18 May 2017 and first published on 19 May 2017


Article type: Paper
DOI: 10.1039/C7NR01874F
Citation: Nanoscale, 2017, Accepted Manuscript
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    Near-Equilibrium Measurement of Quantum Size Effects Using Kelvin Probe Force Microscopy

    T. Späth, M. Popp, C. Pérez León, M. Marz and R. Hoffmann, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR01874F

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