Methods to provide in situ quantification of the effective tip radius in atomic force microscopy

  • Ayoub Glia

Student thesis: Master's Thesis


In this work, two techniques to rapidly quantify in-situ the effective tip radius of atomic force microscopy (AFM) probes are compared. The first method is based on the strong dependency of the free amplitude required to observe a sharp transition from attractive to repulsive force regimes (minimum critical amplitude A_cmin ) on the AFM probe effective radius. Specifically the sharper the tip, the smaller the value of free amplitude required to observe such transition. The second method key trait is to treat the tip-sample as a capacitor. Provided with an analytical model that takes into account the geometry of the tip-sample capacitance, one can reliably quantify the effective size of the tip apex. Flowchart-like algorithms, easily implementable on any machine, are provided for both methods in order to give a guideline to AFM practitioners. The methods' robustness is tested over a range of 21 tips of different tip radii R (i.e. 4 < R < 50nm) and geometries. Results obtained from both methods are compared with the nominal values given by manufacturers and verified by acquiring scanning electron microscopy images. We conclude that, while both methods are reliable and robust over the range of tip sizes tested, the critical amplitude method is more accurate for relatively sharp tips (4 nm < R < 10 nm).
Date of Award2014
Original languageAmerican English
SupervisorMatteo Chiesa (Supervisor)


  • Atomic Force Microscopy(AFM); In-situ.

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