Accuracy and resolution limits of Kelvin probe force microscopy

Zerweck, Ulrich; Loppacher, Christian; Otto, Tobias; Grafström, S.; Eng, Lukas M.

doi:10.1103/physrevb.71.125424

Cited by 403 publications

(461 citation statements)

References 41 publications

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“…In addition, On the other hand, as the AFM tip is broader (25 nm) than the grain boundary itself, the surface potential measured for the grain boundary is not the pure potential of the grain boundary itself [33][34], but a mixed signal of the grain boundary and adjacent space charge layer (defined above as electrical grain boundary) [42]. Therefore, we assume that the actual surface potential difference between grain and of the grain boundary core should be even lower than our measured values.…”

Section: Analysis Of the Defect Formation By Kelvin Probe Force Micromentioning

confidence: 99%

Unveiling the mechanisms of cold sintering of ZnO at 250 °C by varying applied stress and characterizing grain boundaries by Kelvin Probe Force Microscopy

et al. 2018

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The sintering behavior of nanocrystalline ZnO was investigated at only 250 °C. Densification was achieved by the combined effect of uniaxial pressure and the addition of water both in a Field Assisted Sintering Technology/Spark Plasma Sintering apparatus and a warm hand press with a heater holder. The final pure ZnO materials present high densities (> 90 % theoretical density) with nano-grain sizes. By measuring the shrinkage rate as a function of applied stress it was possible to identify the stress exponent related to the densification process. A value larger than one points to non-linear relationship going beyond single solid-state diffusion or liquid phase sintering. Only a low amount of water (1.7 wt.%) was needed since the process is dictated by the adsorption on the surface of the ZnO particles. Part of the adsorbed water dissociates into H + and OH -ions, which diffuse into the ZnO crystal structure, generating grain boundaries/interfaces with high defect chemistry. As characterized by Kelvin Probe Force Microscopy, and supported by impedance spectroscopy, this highly defective grain boundary area presents much higher surface energy than the bulk. This highly defective grain boundary area with high potential reduces the activation energy of the atomic diffusion, leading to sinter the compound at low temperature.

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Section: Analysis Of the Defect Formation By Kelvin Probe Force Micromentioning

confidence: 99%

Unveiling the mechanisms of cold sintering of ZnO at 250 °C by varying applied stress and characterizing grain boundaries by Kelvin Probe Force Microscopy

et al. 2018

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“…Since then, Kelvin probe force microscopy (KPFM) has undergone significant advances in both sensitivity [4][5][6][7] and resolution [8][9][10], with a broad spectrum of configurations now available. KPFM has been applied to study a variety of materials, including organic, biological, and energy conversion and storage-related materials.…”

Section: Introductionmentioning

confidence: 99%

Open loop Kelvin probe force microscopy with single and multi-frequency excitation

et al. 2013

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Abstract. Conventional Kelvin probe force microscopy (KPFM) relies on closed loop (CL) bias feedback for the determination of surface potential (SP). However, SP measured by CL-KPFM has been shown to be strongly influenced by the choice of measurement parameters due to non-electrostatic contributions to the input signal of the bias feedback loop. This often leads to systematic errors of several hundred mV and can also result in topographical crosstalk. Here, open loop (OL)-KPFM modes are investigated as a means of obtaining a quantitative, crosstalk free measurement of the SP of graphene grown on Cu foil, and are directly contrasted with CL-KPFM. OL-KPFM operation is demonstrated in both single and multi-frequency excitation regimes, yielding quantitative SP measurements. The SP difference between single and multilayer graphene structures using OL-KPFM was found to be 63 ± 11 mV, consistent with values previously reported by CL-KPFM. Furthermore, the same relative potential difference between Al 2 O 3 -coated graphene and Al 2 O 3 -coated Cu was observed using both CL and OL techniques. We observe an offset of 55 mV between absolute SP values obtained by OL and CL techniques, which is attributed to the influence of non-electrostatic contributions to the input of the bias feedback used in CL-KPFM.

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“…For conducting surfaces it is well established, that KPFM reveals the so called local contact potential difference (LCPD) with a lateral resolution in the order of the tip front end [35][36][37][38][39][40] . For insulating surfaces and nanoscale contrast, the contrast mechanisms are much more complex since not only the exact geometry of the tip-sample system has to be considered, but also charges and (induced) dipoles within the system (polarization effects) [41][42][43] .…”

Section: Introductionmentioning

confidence: 99%

Polarization effects in noncontact atomic force microscopy: A key to model the tip-sample interaction above charged adatoms

2011

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We discuss the influence of short-range electrostatic forces, so called dipolar forces, between the tip of an atomic force microscope (AFM) and a surface carrying charged adatoms. Dipolar forces are of microscopic character and have their origin in the polarizability of the foremost atoms on tip and surface. In most experiments performed by non-contact AFM, other forces such as binding forces dominate the interaction. However, in the experiments presented by Gross et al. [Science 324, 1428[Science 324, (2009, where the charge state of individual gold atoms adsorbed on a thin dielectric layer was determined, binding forces are negligible as the tip-sample distance is relatively large.We develop a model which mimics the experimental tip-sample geometry of the aforementioned experiments. The model includes van der Waals and long-range electrostatic interactions, as well as the short-range electrostatic interaction based on the self-consistent description of electronic polarization effects on neutral and charged adatoms. The model is based on a calculation of the electrostatic energy of the tip-sample geometry.Our calculations of non-contact AFM imaging as well as of bias spectroscopic curves are in good agreement with the experimental ones presented by Gross et al. It is demonstrated that the short-range dipolar force is mainly responsible for the contrast observed in topography imaging above charged species. However, it is the long-range capacitive force which is responsible for the detection of the charge state in bias spectroscopy. We discuss implications of our findings on future experiments which aim to detect single charges by means of Kelvin probe force microscopy.

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Accuracy and resolution limits of Kelvin probe force microscopy

Cited by 403 publications

References 41 publications

Unveiling the mechanisms of cold sintering of ZnO at 250 °C by varying applied stress and characterizing grain boundaries by Kelvin Probe Force Microscopy

Unveiling the mechanisms of cold sintering of ZnO at 250 °C by varying applied stress and characterizing grain boundaries by Kelvin Probe Force Microscopy

Open loop Kelvin probe force microscopy with single and multi-frequency excitation

Polarization effects in noncontact atomic force microscopy: A key to model the tip-sample interaction above charged adatoms

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