Lateral resolution of electrostatic force microscopy for mapping of dielectric interfaces in ambient conditions

The attainable lateral resolution of electrostatic force microscopy (EFM) in an ambient air environment on dielectric materials was characterized on a reference sample comprised of two distinct, immiscible glassy polymers cut in a cross-section by ultramicrotomy. Such a sample can be modeled as two semi-infinite dielectrics with a sharp interface, presenting a quasi-ideal, sharp dielectric contrast. Electric polarizability line profiles across the interface were obtained, in both lift-mode and feedback-regulated dynamic mode EFM, as a function of probe/surface separation, for different cases of oscillation amplitudes. We find that the results do not match predictions for dielectric samples, but comply well or are even better than predicted for conductive interfaces. A resolution down to 3 nm can be obtained by operating in feedback-regulated EFM realized by adopting constant-excitation frequency-modulation mode. This suggests resolution is ruled by the closest approach distance rather than by average separation, even with probe oscillation amplitudes as high as 10 nm. For better comparison with theoretical predictions, effective probe radii and cone aperture angles were derived from approach curves, by also taking into account the finite oscillation amplitude of the probe, by exploiting a data reduction procedure previously devised for the derivation of interatomic potentials

Extended model for the interaction of dielectric thin films with an electrostatic force microscope probe

To improve measurements of the dielectric permittivity of nanometric portions by means of Local Dielectric Spectroscopy (LDS), we introduce an extension to current analytical models for the interpretation of the interaction between the probe tip of an electrostatic force microscope (EFM) and a thin dielectric film covering a conducting substrate. Using the proposed models, we show how more accurate values for the dielectric constant can be obtained from single-frequency measurements at various probe/substrate distances, not limited to a few tip radii

Nanomaterials-based strategies for piezoelectric cochlear implants

Nanomaterials-based strategies for piezoelectric cochlear implant

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

International audienc

Scanning electro-optic microscopy of ferroelectric domain structure with a near-field fiber probe

Ferroelectric domain structure of barium titanate single crystals has been visualized using a fiber probe near-field microscope, combined with temporal modulation of optical signal provided by a sinusoidal electric field applied to the sample. We find that electro-optic contrast between the adjacent domains depends on the polarization of incident light not as strongly as in case of confocal microscopy. This fact is ascribed to presence of additional optical aberrations caused by the near-field arrangement confirmed by complicated approaching curve observed for the electro-optic signal. Surprising improvement in spatial resolution of the near-field electro-optic image comparing to the optical one has been observed in some cases, supporting the idea of surface-confined electro-optic modulation in qualitative agreement with the observed phenomenon. (C) 2011 American Institute of Physics. [doi:10.1063/1.3656731