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

• 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

• resolution. In particular, in AM-KPFM the electrical force between the tip and the sample is directly evaluated, whereas in FM-KPFM the gradient of the force is analysed. As a result, FM-KPFM is more sensitive to local tip apex–sample surface interactions; therefore, long-range electrostatic interactions of

• the cantilever are reduced, as well as the effect of parasitic capacitances [16]. Additionally, in FM-KPFM, surface potential measurements are less dependent on the lift-height tip–sample distance than in AM-KPFM since this mode is less sensitive to static offsets induced by capacitive coupling or

Comparing the performance of single and multifrequency Kelvin probe force microscopy techniques in air and water

• Jason I. Kilpatrick,
• Emrullah Kargin and
• Brian J. Rodriguez

Beilstein J. Nanotechnol. 2022, 13, 922–943, doi:10.3762/bjnano.13.82

• -mode [14][48][49][50]. The most common application of KPFM in AFM is CL AM-KPFM on the fundamental eigenmode where a bias feedback loop is employed to cancel the electrostatic force and to extract VCPD [10][60][61]. This single-frequency technique can also be used under OL conditions without a feedback

• loop using phase-based detection [71], frequency sweeps [40][64][72], or bias modulation [10][52][73]. The advantages of CL AM-KPFM are that it is easy to implement, is standard on most commercial AFMs, and has high bias sensitivity [74]. The disadvantages of this technique are that it is limited by

• from measurements in order to access a true surface potential map [78][79]. A natural extension of AM-KPFM is dual-harmonic KPFM (DH-KPFM), which is an OL technique that utilizes the measurement of both the first and second harmonic of the electrostatic response (ωe and 2ωe). By combining these two

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

• found in many review articles and book chapters [13][20][21][22][23][24]. The majority of the KPFM implementations are in the form of closed-loop systems, with the tip–sample CPD determined from the nullification [25] of either the electrostatic force as in AM-KPFM [1][26] or the gradient force as in FM

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

• 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

• experimental setup are given in the figure caption and in [7]. The FM- and AM-KPFM data was collected in subsequent measurements with the same cantilever on the same solar cell cross section. However, the resolved potential distributions differed significantly. In dark, the potential drop from FTO to gold

• measured with FM-KPFM was around −0.55 V, while the potential difference between the electrodes detected with AM-KPFM was only −0.25 V. Furthermore, the absolute potential detected in AM-KPFM had an offset of +1 V. The most fundamental difference in the potential distributions imaged in FM- and AM-KPFM

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

• applied at the fundamental resonance frequency of the cantilever (results presented in Figure 2), while a frequency spectrum with a square pulse shape is applied. Experimental results reproducing these conditions are presented in Figure 4a; AM-KPFM was used at the fundamental resonance frequency of the

• 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

• below 1 × 10−10 mbar, controlled by a Nanonis controller. Two types of PtIr-coated cantilevers (Nanosensors PPP) were used, with the fundamental resonance frequency at ≈74 kHz or at ≈165 kHz. Typical oscillation amplitudes of ≈20 nm were mechanically excited. For amplitude modulation (AM) KPFM the

Large area scanning probe microscope in ultra-high vacuum demonstrated for electrostatic force measurements on high-voltage devices

• Urs Gysin,
• Thilo Glatzel,
• Thomas Schmölzer,
• Adolf Schöner,
• Sergey Reshanov,
• Holger Bartolf and
• Ernst Meyer

Beilstein J. Nanotechnol. 2015, 6, 2485–2497, doi:10.3762/bjnano.6.258

• VCPD to nullify the electrostatic force acting between them [9][36]. A very sensitive way to measure, separate, and compensate the electrostatic forces is the so-called amplitude modulated KPFM (AM-KPFM) which uses the second eigenmode of the cantilever [17][37]. By applying an ac voltage Vac to the

• shields is a key property and needs sophisticated characterization [57]. The KPFM experiment presented in Figure 8a and Figure 8b is an example of a large area 70 × 24 μm2 cross section from such a SiC power device determined also by the aforementioned AM-KPFM technique and a PtIr-coated Si cantilever in

Kelvin probe force microscopy of nanocrystalline TiO₂ photoelectrodes

• Alex Henning,
• Gino Günzburger,
• Res Jöhr,
• Yossi Rosenwaks,
• Biljana Bozic-Weber,
• Catherine E. Housecroft,
• Edwin C. Constable,
• Ernst Meyer and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2013, 4, 418–428, doi:10.3762/bjnano.4.49

• H2O and <10 ppm O2) on a commercial microscope (Solver PH-47, NT-MDT). Amplitude modulation (AM) KPFM was conducted with a two-scan method (lift mode) meaning that the topography and CPD were measured separately (Figure 10). During the first line scan the topography was determined in tapping mode AFM

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

• that a simple model of a rigid cantilever is an adequate approximation. The effect of the second resonance In most AM-KPFM single pass measurements an external AC bias, at a frequency ω of the second resonance of the beam, is applied to the entire probe. This oscillation, shown in Figure 7, is

• force on the probe. Line section (vertical line at inset figure) for KPFM simulation with different cantilever geometries. (i) Original measurements, (ii) W = 40 µm, β = 10° (iii) W = 40 µm, β = 20°, (iv) probe without cantilever with β = 0° (normal to the surface). Inset figure: Single pass AM-KPFM