Space Charge at Nanoscale: Probing Injection and Dynamic Phenomena Under Dark/Light Configurations by Using KPFM and C-AFM

International audienc

Les GL(2,R)−GL(2,R)-Orbites des systèmes différentiels plans

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Multi-dimensional modelling of electrostatic forces between atomic force microscopy tip and dielectric surface

In this paper, simulation results for the electrostatic force between an Atomic Force Microscope (AFM) sensor and the surface of a dielectric are presented for different bias voltages on the tip:. The aim is to analyse force-distance curves as AFM detection mode for electrostatic charges. The sensor is composed of a cantilever supporting a conical tip terminated by a spherical apex; the effect of the cantilever is neglected here. Our model of force curve has been developed using the Finite Volume Method. The scheme is based on the Polynomial Reconstruction Operator – PRO-scheme. First results of the computation of electrostatic force for different tip– sample distances, 0 to 600 nm, and for different DC voltage stress applied to the tip, 6 to 25 V, are shown and compared with experimental data in order to validate our approach.This work was supported by Region Midi-Pyrénées (France), by FEDER Funds through COMPETE Program and by Fundação para a Ciência e a Tecnologia (Portugal), within the Project PEst-C/MAT/UI0013/2011

3D modeling of electrostatic interaction between atomic force microscopy probe and dielectric surface: impact of tip shape and cantilever contribution

Techniques derived from the near-field microscopies and particularly the Atomic Force Microscopy (AFM) are presented as alternative techniques for space charge measurement compared to classical techniques due to their high sensitivity to the electrostatic force and an improved spatial resolution (few nanometers). One of the AFM derivative methods, which allow obtaining information on the charge state of the dielectric materials, is based on the measurement of Force Distance Curves (FDC) obtained by cycling approach and retraction of the AFM probe to the dielectric surface. In this paper, three-Dimensional (3D) simulation results for the electrostatic force between an AFM tip and the surface of a dielectric are presented for different AFM tip geometries. The first aim is to analyse the effect of tip shape on electrostatic contribution to force-distance curves. The second step consists in extracting cantilever contribution to electrostatic force. Finally, a model merging cantilever and tip shape contributions is developed. Simulation results are shown and compared with experimental data in order to validate our approach.FEDER Funding through Programa Operacional Factores de Competitividade - COMPETE and by Portuguese Funds through Fundação para a Ciência e a Tecnologia, within the project PTDC/MAT/121185/2010, the project FCT-ANR/MAT-NAN/0122/2012 and the strategic programme PEst-OE/MAT/UI0013/2014 (Portugal