Soft sample deformation, damage and induced electromechanical property changes in contact- and tapping-mode atomic force microscopy

Abstract

Probe-induced soft sample damage in atomic force microscopy (AFM), as well as the resulting alteration of local mechanical and electrical properties of the material are explored, specifically comparing contact-mode and intermittent-contact-mode imaging methods. In our experiments, performed on conductive polymer films, induced changes are present in contact-mode imaging while they are negligible or absent in tapping-mode imaging. To understand this result, a viscoelastic parameter extraction is performed, which suggests that permanent sample deformation can readily occur for tip-sample interactions with a duration on the timescale of contact-mode interactions. Using the extracted viscoelastic parameters, a dynamic AFM simulation is conducted, which suggests that the material responds more elastically with reduced or absent sample damage in tapping-mode AFM, due to the higher rate of mechanical deformation and shorter timescales.

Nanoscale Ferroelectric Characterization with Heterodyne Megasonic Piezoresponse Force Microscopy

“…It has been widely recognized that the two most significant issues faced by PFM are the contact-mode operation and the influences of the electrostatic force (12,15). The contact-mode operation can induce pronounced modifications to both the sample and tip, such as the surface damage, contamination, charge injection and triboelectrification (15,(21)(22)(23)(24)(25)(26) as well as the tip wear, contamination and damage (15,23,24,(26)(27)(28)(29), which will all affect the PFM signal and may cause significant reproducibility problems and artefacts in the measurements. Since the sample and tip modifications are almost inevitable during the contactmode PFM scanning, by far researchers can only have very limited solutions to reduce such effects, such as decreasing the setpoint of force feedback, using softer cantilever and mapping with a point-by-point manner (23,30,31).…”

Corrosion Resistance of Sulfur–Selenium Alloy Coatings

“…At first, a rectangular region of the alloy was scanned in contact mode with a high contact stress (≈1.5 GPa), which resulted in surface dents, as seen in Figure 5a (0 min). After the contact mode scan, a larger area around the pre‐scanned region was continuously scanned for one hour in tapping mode to avoid any sample damage, [ 29 ] which reveals almost complete recovery of the topography. Figure 5b shows the time evolution of the coating morphology when scribed (scanned) with an AFM probe.…”

Linear Viscoelasticity: Review of Theory and Applications in Atomic Force Microscopy

“…In FM-AFM methods it is generally the tip oscillation frequency that is held constant (García, 2010). Dynamic AFM modes offer an advantage over static AFM modes in that they avoid friction and adhesive surface forces, while enacting less destructive deformations on the sample (Gan, 2009;Jalili and Laxminarayana, 2004;Magonov, 2001;Parvini et al, 2020;Saadi et al, 2020). As such, these modes see popular use in the characterization of soft or fragile samples (Jalili and Laxminarayana, 2004).…”