Know your full potential: Quantitative Kelvin probe force microscopy on nanoscale electrical devices

• Amelie Axt,
• Ilka M. Hermes,
• Victor W. Bergmann,
• Niklas Tausendpfund and
• Stefan A. L. Weber

Beilstein J. Nanotechnol. 2018, 9, 1809–1819, doi:10.3762/bjnano.9.172

• modulation (AM) and frequency modulation (FM) KPFM methods on a reference structure consisting of an interdigitated electrode array. This structure mimics the sample geometry in device measurements, e.g., on thin film transistors or on solar cell cross sections. In particular, we investigate how quantitative

• mode; AM off resonance; AM second eigenmode; cross section; crosstalk; field effect transistor; FM-KPFM; frequency modulation heterodyne; frequency modulation sideband; quantitative Kelvin probe force microscopy; solar cells; Introduction In this study, we compare the most commonly used amplitude

• modulation (AM) and frequency modulation (FM) Kelvin probe force microscopy (KPFM) methods under ambient conditions to investigate how these methods can measure quantitative variations in the local contact potential difference (CPD). KPFM is a scanning force microsopcy (SFM) method that correlates the local

Multimodal noncontact atomic force microscopy and Kelvin probe force microscopy investigations of organolead tribromide perovskite single crystals

• Yann Almadori,
• David Moerman,
• Jaume Llacer Martinez,
• Philippe Leclère and
• Benjamin Grévin

Beilstein J. Nanotechnol. 2018, 9, 1695–1704, doi:10.3762/bjnano.9.161

• ) at room temperature (RT) with in situ annealed Pt/Ir-coated silicon cantilevers (EFM, Nanosensors, resonance frequency in the 45–115 kHz range). Topographical imaging was performed in frequency modulation mode (FM-AFM) with negative frequency shifts of a few Hz and vibration amplitudes of a few tens

• of nanometers. KPFM measurements were carried out in single-pass mode under frequency modulation (FM-KPFM) with the modulation bias, VAC (typically 0.5 V peak-to-peak at 1200 Hz), and the compensation voltage, VDC, applied to the cantilever (tip bias Vtip = VDC). The contact potential difference (CPD

• domain allows disentangling the contributions of the photocarriers to the surface photovoltage from the ones due to the light-induced migration of ionic species. Lastly, the effective carrier lifetime has been quantified by analyzing the dependence of the surface potential as a function of the frequency

Electrostatically actuated encased cantilevers

• Benoit X. E. Desbiolles,
• Gabriela Furlan,
• Adam M. Schwartzberg,
• Paul D. Ashby and
• Dominik Ziegler

Beilstein J. Nanotechnol. 2018, 9, 1381–1389, doi:10.3762/bjnano.9.130

• excitation enables more reliable frequency modulation techniques [30] and generally results in quantitative measurements of tip–sample interactions. Harmonic electrostatic excitation In this section we analyze the harmonic excitation mechanism and the influence of Udrive in greater detail. The spectra shown

Artifacts in time-resolved Kelvin probe force microscopy

• Sascha Sadewasser,
• Nicoleta Nicoara and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2018, 9, 1272–1281, doi:10.3762/bjnano.9.119

• second resonance mode of the cantilever was used (f2 ≈ 465 kHz or f2 ≈ 1.027 MHz, respectively), while for frequency modulation (FM) KPFM the ac bias was applied at fac = 377 Hz. In both cases Vac = 200 mV amplitude was used. The induced oscillating electrostatic forces are compensated by a dc voltage

Combined pulsed laser deposition and non-contact atomic force microscopy system for studies of insulator metal oxide thin films

• Daiki Katsube,
• Hayato Yamashita,
• Satoshi Abo and
• Masayuki Abe

Beilstein J. Nanotechnol. 2018, 9, 686–692, doi:10.3762/bjnano.9.63

• not required. The performance of the combined system is demonstrated for the preparation and high-resolution NC-AFM imaging of atomically flat thin films of anatase TiO2(001) and LaAlO3(100). Keywords: atomic resolution; frequency modulation atomic force microscopy; insulator thin film; pulsed laser

• observations. To image the insulator metal oxide thin films with atomic resolution, NC-AFM with the frequency modulation mode is used [51]. A commercial cantilever (Budget Sensors, TAP190) is used to obtain NC-AFM topographic images. An Ar+ sputtering gun is installed in the preparation chamber to clean the

Anchoring of a dye precursor on NiO(001) studied by non-contact atomic force microscopy

• Sara Freund,
• Antoine Hinaut,
• Nathalie Marinakis,
• Edwin C. Constable,
• Ernst Meyer,
• Catherine E. Housecroft and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2018, 9, 242–249, doi:10.3762/bjnano.9.26

• in frequency-modulation mode using an electrical oscillation at a frequency of fac = 900 Hz and with an amplitude Vac = 800 mV applied together with the DC compensation voltage to the sample. Structure of 4,4′-di(4-carboxyphenyl)-6,6′-dimethyl-2,2′-bipyridine. The trans-conformation of DCPDMbpy (left

A robust AFM-based method for locally measuring the elasticity of samples

• Alexandre Bubendorf,
• Stefan Walheim,
• Thomas Schimmel and
• Ernst Meyer

Beilstein J. Nanotechnol. 2018, 9, 1–10, doi:10.3762/bjnano.9.1

• Micro Facility (KNMF), Karlsruhe, Germany 10.3762/bjnano.9.1 Abstract Investigation of the local sample elasticity is of high importance in many scientific domains. In 2014, Herruzo et al. published a new method based on frequency-modulation atomic force microscopy to locally determine the elasticity

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

• Agata Siarkowska,
• Miłosz Chychłowski,
• Daniel Budaszewski,
• Bartłomiej Jankiewicz,
• Bartosz Bartosewicz and
• Tomasz R. Woliński

Beilstein J. Nanotechnol. 2017, 8, 2790–2801, doi:10.3762/bjnano.8.278

• properties. We strongly believe that the presence of metallic NPs could provide even greater improvement to the electro-optical parameters of PLCFs. First attempts to infiltrate a PCF with LCs doped with barium titanate NPs were reported in 2009 [17], providing new features such as frequency modulation

A review of demodulation techniques for amplitude-modulation atomic force microscopy

• Michael G. Ruppert,
• David M. Harcombe,
• Michael R. P. Ragazzon,
• S. O. Reza Moheimani and
• Andrew J. Fleming

Beilstein J. Nanotechnol. 2017, 8, 1407–1426, doi:10.3762/bjnano.8.142

• signal cannot be controlled directly, low-frequency measurables such as the change in oscillation amplitude in amplitude-modulation AFM [11] have to be employed. Other feedback variables such as the shift in cantilever resonance frequency in frequency-modulation AFM [13] or the phase shift in phase

Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis

• Omur E. Dagdeviren and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2017, 8, 657–666, doi:10.3762/bjnano.8.70

• date mostly conducted in frequency modulation (FM) mode, where the reduction of the eigenfrequency f0 upon approach to the surface is the measured quantity (the so-called “frequency shift” Δf) [32]. Since Δf f0/k [33][34][35][36], we have to weight variations in f0 and k combined rather than

Generalized Hertz model for bimodal nanomechanical mapping

• Aleksander Labuda,
• Marta Kocuń,
• Waiman Meinhold,
• Deron Walters and
• Roger Proksch

Beilstein J. Nanotechnol. 2016, 7, 970–982, doi:10.3762/bjnano.7.89

• parameters are considered: amplitude, phase, and frequency modulation. The experimental equivalence of all three modes is demonstrated on measurements of the second eigenmode parameters. The contact mechanics theory is then extended to power-law tip shape geometries, which is applied to analyze the

• imaging modes, such as frequency-modulation (FM) AFM [23]. Separating the storage and loss moduli, and quantifying them, requires either additional independent observables or the use of spectroscopic methods. Spectroscopic techniques rely on changing the operating conditions of the cantilever to provide

• amplitude modulation (AM) [1][18][19], phase modulation (PM) [43][44][45][46] and frequency modulation (FM) [23][36][47]. Finally, a method for extracting the tip size and tip shape from bimodal AFM approach curves is presented and demonstrated on a polystyrene sample. Figure 1 provides a diagram of the

Understanding interferometry for micro-cantilever displacement detection

• Alexander von Schmidsfeld,
• Tobias Nörenberg,
• Matthias Temmen and
• Michael Reichling

Beilstein J. Nanotechnol. 2016, 7, 841–851, doi:10.3762/bjnano.7.76

• measuring displacement in a cantilever-based NC-AFM. This has been realized already in the early days of frequency-modulation force microscopy [2][7][13][17][18]. By instrumental development and optimization, the detection sensitivity has constantly been improved over two decades of development and a force

High-resolution noncontact AFM and Kelvin probe force microscopy investigations of self-assembled photovoltaic donor–acceptor dyads

• Benjamin Grévin,
• Pierre-Olivier Schwartz,
• Laure Biniek,
• Martin Brinkmann,
• Nicolas Leclerc,
• Elena Zaborova and
• Stéphane Méry

Beilstein J. Nanotechnol. 2016, 7, 799–808, doi:10.3762/bjnano.7.71

• morphology characterization using AFM and TEM, ii) the analysis of the surface electrostatic contrast in dark conditions, and finally, iii) the surface photo-voltage characterization of the films under illumination. Methods The nc-AFM experiments were performed in frequency modulation (FM) mode with an

Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

• Santiago D. Solares

Beilstein J. Nanotechnol. 2016, 7, 554–571, doi:10.3762/bjnano.7.49

• frequencies well below the cantilever resonance frequency [21]. Novel spectroscopy methods have also been recently developed for intermittent-contact imaging. For example, it is now possible to extract tip–sample force curves using dual-eigenmode frequency-modulation AFM [10] and intermodulation AFM [11][12

Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air

• Hannes Beyer,
• Tino Wagner and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2016, 7, 432–438, doi:10.3762/bjnano.7.38

• Hannes Beyer Tino Wagner Andreas Stemmer Nanotechnology Group, ETH Zürich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland 10.3762/bjnano.7.38 Abstract Frequency-modulation atomic force microscopy has turned into a well-established method to obtain atomic resolution on flat surfaces, but is often

• ; frequency-modulation atomic force microscopy; high-resolution; length-extension resonator; Introduction Frequency-modulated atomic force microscopy (FM-AFM) is the method of choice to image nanoscale structures on surfaces down to the atomic level. Whereas atomic resolution is routinely achieved in ultra

Kelvin probe force microscopy for local characterisation of active nanoelectronic devices

• Tino Wagner,
• Hannes Beyer,
• Patrick Reissner,
• Philipp Mensch,
• Heike Riel,
• Bernd Gotsmann and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2015, 6, 2193–2206, doi:10.3762/bjnano.6.225

• . Nevertheless, the averaging effect of the cantilever beam remains (see below in Figure 1). An alternative approach typically applied in vacuum is based on frequency modulation [15]. To this end, the frequency of the cantilever is usually tracked by a phase-locked loop (PLL). Its output signal, the frequency

• + Δω with Δω/ω0 = −kts/2k [15]. Accordingly, a modulation of the force gradient, e.g., by an oscillating electric field, will cause a frequency modulation of the resonance. A modulation at a single frequency ωm will produce sidebands at integer multiples of the modulation frequency, that is, cantilever

• . For modulation frequencies well beyond the cantilever bandwidth, G(ω0 ± ωm) ≈ −iω0/2ωm, and the amplitude of each sideband is , where A is the carrier amplitude. The latter expression also follows immediately from a narrow-band frequency modulation of a carrier oscillation at ωd. With a carrier

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

• Tobias Meier,
• Alexander Förste,
• Ali Tavassolizadeh,
• Karsten Rott,
• Dirk Meyners,
• Roland Gröger,
• Günter Reiss,
• Eckhard Quandt,
• Thomas Schimmel and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2015, 6, 451–461, doi:10.3762/bjnano.6.46

• materials is observable and the holes in the FDTS-SAM are visible as bright spots in the phase signal. As the phase contrast on this sample system is higher, we altered the feedback and scanned the same sample in a frequency modulation mode [66]. Thereby, the resonance frequency of the cantilever was

• samples, phase-locked frequency modulation AFM is advantageous and can reveal the topography of the sample. As the cantilevers resonance frequency is fed back to the driving signal by an additional loop, the phase contrast vanishes and is constant at 90°, while the topography with the holes in the SAM is

Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM

• Kfir Kuchuk and
• Uri Sivan

Beilstein J. Nanotechnol. 2015, 6, 149–156, doi:10.3762/bjnano.6.14

• conservative and dissipative forces in terms of an arbitrary single harmonic. Additionally, we show that in frequency modulation-AFM (FM-AFM) each harmonic carries complete information on the force, obviating the need for multi-harmonic analysis. Finally, we show that higher harmonics may indeed be used to

• resonance frequency. In frequency modulation-AFM (FM-AFM), the force is usually reconstructed from the resonance frequency shift, which in the small amplitude regime is proportional to the derivative of the force with respect to tip–surface distance. Similarly, it has been recognized that higher harmonics

Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1649–1663, doi:10.3762/bjnano.5.176

• ; frequency modulation; multi-frequency atomic force microscopy; viscoelasticity; standard linear solid; Introduction Atomic force microscopy (AFM) has developed considerably since its introduction in the mid-1980s, and today constitutes one of the most powerful and versatile tools in nanotechnology [1][2][3

• and Garcia [11][12], which is the most common, but some of the discussion is also applicable to bimodal methods involving frequency-modulation (FM-AFM [3][9][18][27]. Characterization of viscoelastic surfaces with AFM Viscoelastic characterization is generally performed with contact-mode-based methods

• contrast. In addition, one can more rigorously describe the conservative and dissipative interactions by quantifying them in terms of the virial (Vts) and average dissipated power (Pts), for which equations have been previously published for use within amplitude- [30][32][33] and frequency-modulation [34

Multi-frequency tapping-mode atomic force microscopy beyond three eigenmodes in ambient air

• Santiago D. Solares,
• Sangmin An and
• Christian J. Long

Beilstein J. Nanotechnol. 2014, 5, 1637–1648, doi:10.3762/bjnano.5.175

• future research opportunities. Keywords: amplitude-modulation; bimodal; frequency-modulation; multi-frequency atomic force microscopy; multimodal; open loop; trimodal; Introduction Multi-frequency atomic force microscopy (AFM) refers to a family of techniques in which the microcantilever probe is

• physically meaningful, since it does not guarantee that the contrast eigenmodes conform to the assumed ideal response. In contrast, if frequency modulation methods are used to drive the higher modes [5][7][27], it is necessary that the frequency response be well behaved both to ensure the stability of the

• perturbed enough to compromise the stability of a frequency modulation drive. Figure 5 illustrates the amplitude response of the second eigenmode within pentamodal operation when using conditions that are close to those used to construct Figure 2 and Figure 3, for different amplitudes of the higher

Trade-offs in sensitivity and sampling depth in bimodal atomic force microscopy and comparison to the trimodal case

• Babak Eslami,
• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1144–1151, doi:10.3762/bjnano.5.125

• generally smaller than that of the fundamental mode, it can be made more sensitive to compositional contrast, as previously discussed by Rodriguez and Garcia [12]. The two eigenmodes can also be driven using the frequency modulation scheme (FM-AFM [4][15][16][17]), and it is also possible to simultaneously

Impact of thermal frequency drift on highest precision force microscopy using quartz-based force sensors at low temperatures

• Florian Pielmeier,
• Daniel Meuer,
• Daniel Schmid,
• Christoph Strunk and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2014, 5, 407–412, doi:10.3762/bjnano.5.48

• Florian Pielmeier Daniel Meuer Daniel Schmid Christoph Strunk Franz J. Giessibl Institute of Experimental and Applied Physics, University of Regensburg, D-93053 Regensburg, Germany 10.3762/bjnano.5.48 Abstract In frequency modulation atomic force microscopy (FM-AFM) the stability of the

• detector noise. Keywords: AFM; frequency drift; length extensional resonator; needle sensor; qPlus sensor; quartz; Findings Frequency modulation atomic force microscopy [1] has become an essential tool for surface scientist‘s to study chemical and magnetic interactions at the atomic scale [2][3][4][5][6

Challenges and complexities of multifrequency atomic force microscopy in liquid environments

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 298–307, doi:10.3762/bjnano.5.33

• discussion are mostly applicable to the cases where higher eigenmodes are driven in open loop and frequency modulation within bimodal schemes, but some concepts are also applicable to other types of multifrequency operations and to single-eigenmode amplitude and frequency modulation methods. Keywords

• : amplitude-modulation; bimodal; frequency-modulation; liquids; multifrequency atomic force microscopy; Introduction Multifrequency atomic force microscopy (AFM) refers to a family of techniques that involve simultaneous excitation of the microcantilever probe at more than one frequency [1]. The first of

• extended to intermittent contact characterization using open loop and frequency modulation [3][4], imaging in liquid and vacuum environments [5][6][7][8], and to trimodal operation [9][10][11]. There also exist a number of other multifrequency and multiharmonic AFM techniques which have been developed for

Frequency, amplitude, and phase measurements in contact resonance atomic force microscopies

• Gheorghe Stan and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 278–288, doi:10.3762/bjnano.5.30

• is provided. Keywords: contact-resonance AFM; dynamic AFM; frequency modulation; phase-locked loop; viscoelasticity; Introduction A number of atomic force microscopy (AFM) variants have emerged since the introduction of the original technique in 1986 [1]. Besides topographical acquisition and

• , similar with what is used in non-contact frequency modulation AFM. In non-contact AFM, PLL tracking has been implemented in either constant-excitation frequency modulation [17][18] or constant-amplitude frequency-modulation [19][20]. In the following we will refer only to the constant-excitation PLL setup

Unlocking higher harmonics in atomic force microscopy with gentle interactions

• Sergio Santos,
• Victor Barcons,
• Josep Font and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2014, 5, 268–277, doi:10.3762/bjnano.5.29

• , and by driving with sufficiently small (sub-nanometer) second mode amplitudes, the first mode amplitude [24] or frequency [17] can be employed to track the sample in amplitude or frequency modulation (AM and FM), respectively. The second mode can then be left as an open loop for high sensitivity