  The denominated surface charge scraping mechanism was discovered in 2014 by
using a new Atomic Force Microscopy (AFM) based mode called Charge Gradient
Microscopy. The measurements to probe such mechanism are achieved with the use
of a current-to-voltage converter: a transimpedance amplifier (TIA). However,
the use of an incorrect approximation, named Gain BandWidth Product (GBWP) to
calculate TIAs BandWidth (BW) could mislead to an incorrect data
interpretation. By measuring at higher frequencies than permitted, the
amplifier is used as a current-to-voltage converter, in conditions where it
behaves as a charge-to-voltage converter. In this manuscript, we report the
specific conditions in which the transfer function of the same electronic
circuit topology is valid, while we spot both ringing and unstable amplifiers
artifacts in the published data. We finally perform physical measurements in
similar conditions as reported, but fully respecting the BandWidth (BW) of the
system. We find that the charge collected is way below the values reported in
such publication, diminishing or even nullifying the impact of a possible
charge scrapping mechanism. These findings pave the way to employ Direct
Piezoelectric Force Microscopy (DPFM) as a fast ferroelectric nanoscale
characterization tool.
