Open-loop amplitude-modulation Kelvin probe force microscopy operated in single-pass PeakForce tapping mode

Beilstein Journal of Nanotechnology

article

Gheorghe Stan¹  Pradeep Namboodiri² 

[1] Material Measurement Laboratory, National Institute of Standards and Technology;Physical Measurement Laboratory, National Institute of Standards and Technology

关键词: electrostatic interaction;    Kelvin probe force microscopy;    open loop;    surface potential;   

DOI  :  10.3762/bjnano.12.83

学科分类：环境监测和分析

来源: Beilstein - Institut zur Foerderung der Chemischen Wissenschaften

【 摘 要 】

The open-loop (OL) variant of Kelvin probe force microscopy (KPFM) provides access to the voltage response of the electrostaticinteraction between a conductive atomic force microscopy (AFM) probe and the investigated sample. The measured response canbe analyzed a posteriori, modeled, and interpreted to include various contributions from the probe geometry and imaged features ofthe sample. In contrast to this, the currently implemented closed-loop (CL) variants of KPFM, either amplitude-modulation (AM) orfrequency-modulation (FM), solely report on their final product in terms of the tip–sample contact potential difference. In ambientatmosphere, both CL AM-KPFM and CL FM-KPFM work at their best during the lift part of a two-pass scanning mode to avoid thedirect contact with the surface of the sample. In this work, a new OL AM-KPFM mode was implemented in the single-pass scan ofthe PeakForce Tapping (PFT) mode. The topographical and electrical components were combined in a single pass by applying theelectrical modulation only in between the PFT tip–sample contacts, when the AFM probe separates from the sample. In this way,any contact and tunneling discharges are avoided and, yet, the location of the measured electrical tip–sample interaction is directlyaffixed to the topography rendered by the mechanical PFT modulation at each tap. Furthermore, because the detailed response ofthe cantilever to the bias stimulation was recorded, it was possible to analyze and separate an average contribution of the cantileverto the determined local contact potential difference between the AFM probe and the imaged sample. The removal of this unwantedcontribution greatly improved the accuracy of the AM-KPFM measurements to the level of the FM-KPFM counterpart.

【 授权许可】

CC BY