Models for quantitative charge imaging by atomic force microscopy

Abstract

Two models are presented for quantitative charge imaging with an atomic-force microscope. The first is appropriate for noncontact mode and the second for intermittent contact ͑tapping͒ mode imaging. Different forms for the contact force are used to demonstrate that quantitative charge imaging is possible without precise knowledge of the contact interaction. From the models, estimates of the best charge sensitivity of an unbiased standard atomic-force microscope cantilever are found to be on the order of a few electrons.

Probing electron charging in nanocrystalline Si dots using Kelvin probe force microscopy

“…In that sense, the KFM is different from other noncontact or tapping mode measurements, in which the topographic images are indeed affected by all types of forces, and the charge transferred from tip to sample is estimated only in an indirect manner, in which the topographic height change (or apparent height) is analyzed. 12,16 It is worth mentioning that the potential imaging is dramatically improved in this work compared with those reported in the past, 17 where the distinction was unclear between the potential of dots and that of the substrate. This is attributable to the method that we used for charging the individual Si dots using the AFM tip without affecting the potential of the substrate overall.…”

Study of charge quantization in individual silicon quantum dots using Kelvin Probe Force Microscopy

“…Therefore charging the sample has no effects on the sample topography obtained with the KFM. In that sense the KFM is different from other non-contact or tapping mode measurements, in which the topographic images are indeed affected by all types of forces, and the charge transferred from tip to sample is estimated only in an indirect manner, in which the topographic height change (or apparent height) is analyzed [9,11].…”

Charge retention characteristics of silicon nanocrystal layers by ultrahigh vacuum atomic force microscopy

“…12 Force gradient changes the cantilever's apparent spring constant and resonant frequency, and the change of resonant frequency shift is a preset parameter in nc-AFM operation. By using the model for noncontact mode, 14 the dynamic problem can be simulated by obtaining a curved surface with a constant force gradient,…”