Dual-heterodyne Kelvin probe force microscopy

• Benjamin Grévin,
• Fatima Husainy,
• Dmitry Aldakov and
• Cyril Aumaître

Beilstein J. Nanotechnol. 2023, 14, 1068–1084, doi:10.3762/bjnano.14.88

• charging corresponds to a positive Vdc change). Actually, there are many ways to perform the signal demodulation. Amplitude heterodyne KPFM, introduced in 2012 by Sugawara et al. [17], is a very elegant approach. It combines the advantages of frequency-modulated KPFM (FM-KPFM) and amplitude-modulated KPFM

• proportional to the dc potential difference, and one works (like in frequency-modulation KPFM) on a signal that is proportional to the electrostatic force gradient (through C''z). For that reason, this “side-band” KPFM is often referred to as a variant of FM-KPFM. Amplitude-modulated heterodyne KPFM [17

• active electrostatic compensation. However, as in the case of pump-probe KPFM [4][10], it is possible to use a second additional FM-KPFM loop which cancels the "time-averaged" dc part of the potential. This feature will not be used in this work, but its implementation has been validated. In the schematic

Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives

• Mattia da Lisca,
• José Alvarez,
• James P. Connolly,
• Nicolas Vaissiere,
• Karim Mekhazni,
• Jean Decobert and
• Jean-Paul Kleider

Beilstein J. Nanotechnol. 2023, 14, 725–737, doi:10.3762/bjnano.14.59

• photogenerated carrier distributions. The analysis of the KPFM data was assisted by means of theoretical modelling simulating the energy bands profile and KPFM measurements. Keywords: FM-KPFM; frequency-modulated Kelvin probe force microscopy; III–V multilayer stack; Kelvin probe modelling; KP modelling; SPV

• KPFM signal [15]. KPFM was performed using a scanning probe microscopy system from AIST-NT (TRIOS platform) under ambient conditions and operated in the frequency-modulated KPFM (FM-KPFM) mode using a two-pass scanning mode, where the second pass was performed at a constant distance of 10 nm from the

• sample surface. Topographical data were collected on the first pass, whereas VCPD was measured during the second one. The schematic of our KPFM setup is depicted in Figure 1. The FM-KPFM mode was chosen over the amplitude-modulation mode (AM-KPFM) since it is well known that it provides better spatial

High–low Kelvin probe force spectroscopy for measuring the interface state density

• Ryo Izumi,
• Masato Miyazaki,
• Yan Jun Li and
• Yasuhiro Sugawara

Beilstein J. Nanotechnol. 2023, 14, 175–189, doi:10.3762/bjnano.14.18

• with respect to the cutoff frequency fc of carrier transport between the bulk and interface states and measuring the difference in CPD by KPFM. In high–low KPFM, frequency modulation (FM) KPFM (FM-KPFM) combined with FM-AFM is used to detect the tip–sample interaction force. FM-KPFM has several

• advantages, namely high sensitivity to the electrostatic force gradient, high detection sensitivity using a cantilever with a weak spring constant at the first resonance, ease of implementation in adding FM-AFM, and no need to enhance the bandwidth of the cantilever deflection sensor. FM-KPFM is used to

• apply an AC bias voltage at frequencies lower than the cutoff frequency fc of carrier transport, and heterodyne FM-KPFM, based on the heterodyne effect (frequency conversion effect) between mechanical oscillation of the cantilever and electrostatic force oscillation, is used to apply an AC bias voltage

Direct measurement of surface photovoltage by AC bias Kelvin probe force microscopy

• Masato Miyazaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2022, 13, 712–720, doi:10.3762/bjnano.13.63

• changes in surface potential induced by modulated external disturbances such as electric fields, magnetic fields [70][71], and stress fields [72][73]. Appendix Sensitivity of AC-KPFM in the FM mode The sensitivity of AC-KPFM in the FM mode is comparable to the sensitivity of FM-KPFM. The frequency noise

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

• Gheorghe Stan and
• Pradeep Namboodiri

Beilstein J. Nanotechnol. 2021, 12, 1115–1126, doi:10.3762/bjnano.12.83

• potential difference. In ambient atmosphere, both CL AM-KPFM and CL FM-KPFM work at their best during the lift part of a two-pass scanning mode to avoid the direct contact with the surface of the sample. In this work, a new OL AM-KPFM mode was implemented in the single-pass scan of the PeakForce Tapping

• of the cantilever to the determined local contact potential difference between the AFM probe and the imaged sample. The removal of this unwanted contribution greatly improved the accuracy of the AM-KPFM measurements to the level of the FM-KPFM counterpart. Keywords: electrostatic interaction; Kelvin

• on the gradient of the tip–sample electrostatic force and are less sensitive to the stray capacitive couplings outside the immediate vicinity of the AFM tip [48]. This increases the measurement accuracy of FM-KPFM in both CL and OL configurations [36][49][50]. It has also been demonstrated that the

Reconstruction of a 2D layer of KBr on Ir(111) and electromechanical alteration by graphene

• Zhao Liu,
• Antoine Hinaut,
• Stefan Peeters,
• Sebastian Scherb,
• Ernst Meyer,
• Maria Clelia Righi and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2021, 12, 432–439, doi:10.3762/bjnano.12.35

• –800 pm and a typical quality factor of Q2 = 10,000) with the torsional resonance detection (frequency of ft ≈ 1.5 MHz, amplitude of At = 20–80 pm and a typical quality factor of Qt = 100,000) [50][52]. Kelvin probe force microscopy (KPFM) was performed in FM-KPFM mode by applying a DC compensation and

Implementation of data-cube pump–probe KPFM on organic solar cells

• Benjamin Grévin,
• Olivier Bardagot and
• Renaud Demadrille

Beilstein J. Nanotechnol. 2020, 11, 323–337, doi:10.3762/bjnano.11.24

• describe the general setup that has been used to implement data-cube pump–probe-KPFM (Figure 1b and Figure 1c). Additional technical information is provided in the experimental section. We kept the standard SPM controller configuration for frequency-modulation KPFM (FM-KPFM). Here, the electrostatic forces

• amplitudes of a few tens of nm. KPFM measurements were carried out in single-pass mode using FM (FM-KPFM) with a peak-to-peak modulation bias Vac of 0.9 V at 1140 Hz. The compensation voltage Vdc was applied to the cantilever (tip bias Vtip = Vdc). The CPD is therefore the negative of Vdc, hence Vtip = Vdc

• signal as a function of the pump–probe delay Δt. The topographic scan is performed by closed-loop z-regulation simultaneously with “conventional” FM-KPFM imaging. Before recording each spectroscopic pixel, the tip is stopped. The z-regulation is kept during an initial stabilization delay prior to

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

• Dominik Wrana,
• Karol Cieślik,
• Wojciech Belza,
• Christian Rodenbücher,
• Krzysztof Szot and
• Franciszek Krok

Beilstein J. Nanotechnol. 2019, 10, 1596–1607, doi:10.3762/bjnano.10.155

• the advantages and limitations of the FM-KPFM technique using the example of a newly discovered TiO/SrTiO3(100) (metal/insulator) heterostructure, which has potentially high technological relevance [12]. Now it would be justified to introduce both TiO and SrTiO3 oxides, highlighting the differences

• correlate directly with the work function differences as provided by the KPFM measurements taken at the very same area. This was possible by forcing the same conductive contact AFM tip to oscillate at higher harmonics to enter the FM-KPFM mode (more details can be found in [29]). Figure 2d,e presents the

• resolution approaches the topography resolution, which is the ultimate physical limit of the FM-KPFM technique [11]. Similar results were obtained for the resolution estimation for KBr nanoislands of monoatomic thickness, where a resolution of 0.5 was obtained for 20 nm separation, as is the case in the

A scanning probe microscopy study of nanostructured TiO₂/poly(3-hexylthiophene) hybrid heterojunctions for photovoltaic applications

• Laurie Letertre,
• Roland Roche,
• Olivier Douhéret,
• Hailu G. Kassa,
• Denis Mariolle,
• Nicolas Chevalier,
• Łukasz Borowik,
• Philippe Dumas,
• Benjamin Grévin,
• Roberto Lazzaroni and
• Philippe Leclère

Beilstein J. Nanotechnol. 2018, 9, 2087–2096, doi:10.3762/bjnano.9.197

• during the measurement, without illumination. This result aims at demonstrating the absence of floating potential across the layer composing the sample. Figure S2 shows the superimposition of FM-KPFM height and Vcpd profiles over a nanostructured TiO2 film obtained in UHV and recorded with and without

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

• different KPFM methods can measure a predefined externally applied voltage difference between the electrodes. We found that generally, FM-KPFM methods provide more quantitative results that are less affected by the presence of stray electric fields compared to AM-KPFM methods. Keywords: AM-KPFM; AM lift

• 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

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

• 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

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

• conditions used in the simulations presented in the previous section, a typical experiment would use the fundamental eigenmode for the z feedback and either use the second eigenmode for the Kelvin feedback in AM-KPFM (by applying the detection ac bias on the second eigenmode) or use FM-KPFM and apply an ac

• bias for the Kelvin detection in the range below ≈1 kHz. We thus used FM-KPFM to test the effect of the frequency spectra for time-resolved KPFM in realistic experimental conditions. For the experiments, a cantilever with a fundamental resonance frequency of f0 = 165.448 kHz was used and the ac-bias

• voltage for the FM-KPFM detection was applied at 377 Hz with Vac = 200 mV. A frequency spectrum with a square-shaped bias pulse was applied with 50% duty cycle. In case of a disabled z feedback, the spectrum shows a slight deviation from the otherwise nearly featureless CPD spectrum at the fundamental

The role of the cantilever in Kelvin probe force microscopy measurements

• George Elias,
• Thilo Glatzel,
• Ernst Meyer,
• Alex Schwarzman,
• Amir Boag and
• Yossi Rosenwaks

Beilstein J. Nanotechnol. 2011, 2, 252–260, doi:10.3762/bjnano.2.29

• measure the surface topography, while the oscillations due to the electrostatic force (in amplitude modulated AM-KPFM at the second resonance or in frequency modulated FM-KPFM at several hundred Hz [16]) are nullified by adjusting Vdc(r). The first resonance oscillations have a strong effect on the

• and in the absolute value of the measured potential. This suggests that the cantilever must be taken into account in quantitative surface potential measurements. Longer tips or FM-KPFM will reduce the cantilever contribution and improve the measurement precision. In the second part of this paper, we