Advanced atomic force microscopy techniques V

• Philipp Rahe,
• Ilko Bald,
• Nadine Hauptmann,
• Regina Hoffmann-Vogel,
• Harry Mönig and
• Michael Reichling

Beilstein J. Nanotechnol. 2025, 16, 54–56, doi:10.3762/bjnano.16.6

• et al. addresses the significantly increased precision of force spectroscopy measurements when performed with a quartz cantilever allowing to reduce the oscillation amplitude to values in the low picometer regime [2]. As the conversion of frequency-shift to force data critically depends on the

• accurate knowledge of the quartz cantilever stiffness, the authors develop a method to quantify the stiffness based on thermal noise measurements and numerical simulation. Calibrated measurements of conductivity and resistivity are the focus of the contribution by Piquemal et al. [3]. A particular

• . Khachartryan et al. highlight the strength of cantilever displacement detection with a Michelson-type fibre interferometer and provide a model for interferometric signal generation [4]. The interferometer response is slightly nonlinear under typical NC-AFM working conditions, while a large cantilever

New design of operational MEMS bridges for measurements of properties of FEBID-based nanostructures

• Bartosz Pruchnik,
• Krzysztof Kwoka,
• Ewelina Gacka,
• Dominik Badura,
• Piotr Kunicki,
• Andrzej Sierakowski,
• Paweł Janus,
• Tomasz Piasecki and
• Teodor Gotszalk

Beilstein J. Nanotechnol. 2024, 15, 1273–1282, doi:10.3762/bjnano.15.103

• different FIB parameters. An example of such a setup would be the cantilever described in [43]. On the base of the aligned opMEMS, a FEBID nanowire was deposited (Figure 7a) in a single-step process, where point-by-point deposition was performed along the pattern line using the following parameters: 5 keV

• stresses in thin films by deflecting a cantilever of defined size from a uniform membrane. We see a need for such experiments for future improvement of our proposed RoI spacing tuning method. The proposed approach allowed us to evaluate the leakage currents separately from the nanodevice properties. It was

Signal generation in dynamic interferometric displacement detection

• Knarik Khachatryan,
• Simon Anter,
• Michael Reichling and
• Alexander von Schmidsfeld

Beilstein J. Nanotechnol. 2024, 15, 1070–1076, doi:10.3762/bjnano.15.87

• to the harmonic displacement of the cantilever in the time domain. As the interferometer signal is limited in amplitude because of the spatial periodicity of the interferometer light field, an increasing cantilever oscillation amplitude creates an output signal with an increasingly complex temporal

• structure. By the fit of a model to the measured time-domain signal, all parameters governing the interferometric displacement signal can precisely be determined. It is demonstrated, that such an analysis specifically allows for the calibration of the cantilever oscillation amplitude with 2% accuracy

• between the light beams reflected from the fiber end (reference beam) and the cantilever (cavity beam), creating a standing wave pattern in the fiber with a spatial periodicity given by the light wavelength λ and a phase ϕ determined by the distance d between the fiber end and the cantilever. Any

Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

• Mario Navarro-Rodriguez,
• Andres M. Somoza and
• Elisa Palacios-Lidon

Beilstein J. Nanotechnol. 2024, 15, 767–780, doi:10.3762/bjnano.15.64

• invasive mode, the driving excitation frequency can be fixed at, or near, the free resonance frequency of the cantilever, or tracked by using a phase-locked loop (PLL) to keep the system always in resonance. If the driving excitation frequency is kept fixed, the phase variations contain information about

Enhancing higher-order modal response in multifrequency atomic force microscopy with a coupled cantilever system

• Wendong Sun,
• Jianqiang Qian,
• Yingzi Li,
• Yanan Chen,
• Zhipeng Dou,
• Rui Lin,
• Peng Cheng,
• Xiaodong Gao,
• Quan Yuan and
• Yifan Hu

Beilstein J. Nanotechnol. 2024, 15, 694–703, doi:10.3762/bjnano.15.57

• traditional rectangular cantilever is weaker in air, which affects the sensitivity of multifrequency AFM detection. To address this issue, we previously proposed a bridge/cantilever coupled system model to enhance the higher-order modal response of the cantilever. This model is simpler and less costly than

• performance of the coupled system with that of traditional cantilevers and quantify the enhancement in higher-order modal response. Also, the optimal conditions for the enhancement of macroscale cantilever modal response are explored. Additionally, we also supplement the characteristics of this model

• , including increasing the modal frequency of the original cantilever and generating additional resonance peaks, demonstrating the significant potential of the coupled system in various fields of AFM. Keywords: atomic force microscopy; coupled system; higher-order modes; macroscale; multifrequency AFM

AFM-IR investigation of thin PECVD SiO_x films on a polypropylene substrate in the surface-sensitive mode

• Hendrik Müller,
• Hartmut Stadler,
• Teresa de los Arcos,
• Adrian Keller and
• Guido Grundmeier

Beilstein J. Nanotechnol. 2024, 15, 603–611, doi:10.3762/bjnano.15.51

• absorption of IR photons results in molecular vibrations in the material under investigation. This photon absorption also causes the thermal expansion of the material. The resulting photothermally generated tip–sample force is measured via changes in the deflection signal of the AFM cantilever. The

• of the cantilever was used as detection mode at 205 kHz. The drive mode was set to 845 kHz, which equals a higher contact resonance mode. The spectra were collected with a spectral resolution of 4 cm−1, and the phase-locked loop (PLL) was disabled for collecting the spectra. In addition to these

• source with two lock-in amplifiers. Nonlinear coupling of these processes in a small volume underneath the tip generates a surface expansion behavior containing the mixing frequencies, which are transferred into the cantilever deflection. Either the sum (C+M) or difference (C−M) frequency is chosen for

Stiffness calibration of qPlus sensors at low temperature through thermal noise measurements

• Laurent Nony,
• Sylvain Clair,
• Daniel Uehli,
• Aitziber Herrero,
• Jean-Marc Themlin,
• Andrea Campos,
• Franck Para,
• Alessandro Pioda and
• Christian Loppacher

Beilstein J. Nanotechnol. 2024, 15, 580–602, doi:10.3762/bjnano.15.50

• little precision. An accurate stiffness calibration is therefore mandatory if accurate force measurements are targeted. In nc-AFM, the probe may either be a silicon cantilever, a quartz tuning fork (QTF), or a length extensional resonator (LER). When used in ultrahigh vacuum (UHV) and at low temperature

• Calibration Methods: A Brief Review This section reminds some salient results about stiffness calibration methods reported in the literature, which forms the context of the present study. In the following, unless specified otherwise, the word “probe” either means a silicon cantilever or the free prong of a

• Equation 5. As for Q2 and Q3, there are few results in the literature on how they are expected to vary in UHV. Usually, the quality factor decreases with n (cf. [87] and silicon cantilever P5 in [56]). We therefore have set arbitrary values following that trend. The simulated temperature is 9.8 K. We first

Design, fabrication, and characterization of kinetic-inductive force sensors for scanning probe applications

• August K. Roos,
• Ermes Scarano,
• Elisabet K. Arvidsson,
• Erik Holmgren and
• David B. Haviland

Beilstein J. Nanotechnol. 2024, 15, 242–255, doi:10.3762/bjnano.15.23

• microscopy based on electromechanical coupling due to a strain-dependent kinetic inductance of a superconducting nanowire. The force sensor is a bending triangular plate (cantilever) whose deflection is measured via a shift in the resonant frequency of a high-Q superconducting microwave resonator at 4.5 GHz

• the coupling to the transmission line used to measure the microwave resonance. A detailed description of our fabrication is presented, including information about the process parameters used for each layer. We also discuss the fabrication of sharp tips on the cantilever using focused electron beam

• , gravitational waves acting on a 40 kg mirror in LIGO [3], or atomic-scale tip–surface forces acting on a 40 pg cantilever in an atomic force microscope (AFM). For AFM cantilevers operating at room temperature close to their fundamental resonant frequency in the kilohertz-to-megahertz range, optical

Quantitative wear evaluation of tips based on sharp structures

• Ke Xu and
• Houwen Leng

Beilstein J. Nanotechnol. 2024, 15, 230–241, doi:10.3762/bjnano.15.22

• , making it ideal for reverse imaging of the AFM probe tip to detect tip wear. AFM images were acquired using a Bruker Icon AFM system in tapping mode. The AFM probe used for AFM imaging was a Bruker FESPA-V2 probe. The cantilever was 225 µm long, 35 µm wide, and had a spring constant of 2.8 N/m. The

• working distance of 10–15 mm. Figure 7 presents an SEM image showcasing a probe tip with a rectangular cantilever and a triangular pyramid shape. The actual 3D morphology of the probe obtained using the 3D scanning results of the sample is shown in Figure 8. The analysis of the contour map of the probe

• scan images of the TipCheck sample. (a) 2D topography image and (b) 3D topography image. Extraction of scan line feature points. SEM images of AFM tips. (a) Image of tip and cantilever beam and (b) image of the tip; the dotted frame is a partially enlarged view of the tip. Reconstructed probe model. (a

Enhanced feedback performance in off-resonance AFM modes through pulse train sampling

• Mustafa Kangül,
• Navid Asmari,
• Santiago H. Andany,
• Marcos Penedo and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2024, 15, 134–143, doi:10.3762/bjnano.15.13

• at frequencies far away from the resonance frequency of the cantilever (off-resonance tapping (ORT) modes) can provide high-resolution imaging of a wide range of sample types, including biological samples, soft polymers, and hard materials. These modes offer precise and stable control of vertical

• reads the deflection of the cantilever and keeps the applied tip–sample vertical force at a fixed setpoint value by adjusting the voltage applied to a Z axis nano-positioner. While this AFM mode achieves high precision in controlling vertical forces, the high lateral forces applied while scanning limits

• the application of this AFM method when gentle and non-damaging imaging is required, for instance on soft biological materials [1]. In order to make the instrument technique suitable for imaging fragile samples, several dynamic modes that rely on the resonance characteristics of the cantilever have

Determination of the radii of coated and uncoated silicon AFM sharp tips using a height calibration standard grating and a nonlinear regression function

• Perawat Boonpuek and
• Jonathan R. Felts

Beilstein J. Nanotechnol. 2023, 14, 1200–1207, doi:10.3762/bjnano.14.99

• strongly depend on the geometry of the AFM tip [7][8]. For example, the Pt-coated HQ:NSC18/Pt tip (for electrical force modulation AFM probes) and the Cr/Au-coated HQ:NSC16/Cr-Au tip (for tapping mode AFM probes with long AFM cantilever) produced by MikroMasch [9] have estimated nominal tip radii lower

• very sharp tips that can make a smaller difference in the scanned profile offset at the corners of the characterizer. A method for characterizing blunt tips was also demonstrated. Nanoindentation using four blunt tips on an AFM cantilever was performed in a normal loading process on a soft PVC sheet

• this measurement, the tip radius profile can be directly determined by the deflection and position signal of the AFM cantilever during contact between that edge surface and the tip end. Our point of interest for determining the tip radius using this standard grate is that the corner edge of the grate

Spatial variations of conductivity of self-assembled monolayers of dodecanethiol on Au/mica and Au/Si substrates

• Julian Skolaut,
• Jędrzej Tepper,
• Federica Galli,
• Wulf Wulfhekel and
• Jan M. van Ruitenbeek

Beilstein J. Nanotechnol. 2023, 14, 1169–1177, doi:10.3762/bjnano.14.97

• . In this mode of CAFM operation, a force–distance curve is measured at every pixel of the image. The tip is approached until a certain bend of the cantilever is reached, corresponding to the force setpoint Fsetpoint. Plotting the z position at which the force setpoint is reached provides the

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

• time-periodic surface electrostatic potential generated under optical (or electrical) pumping with an atomic force microscope. The modulus and phase coefficients are probed by exploiting a double heterodyne frequency mixing effect between the mechanical oscillation of the cantilever, modulated

• components of the time-periodic electrostatic potential at harmonic frequencies of the pump, and an ac bias modulation signal. Each harmonic can be selectively transferred to the second cantilever eigenmode. We show how phase coherent sideband generation and signal demodulation at the second eigenmode can be

• with the application of a light pulse (i.e., a curve is recorded at each point of the surface along a 2D grid). Again, a differential SPV image can be reconstructed from the matrix of spectroscopic curves [5]. However, this approach is not free from artefacts, in particular the cantilever photothermal

Spatial mapping of photovoltage and light-induced displacement of on-chip coupled piezo/photodiodes by Kelvin probe force microscopy under modulated illumination

• Zeinab Eftekhari,
• Nasim Rezaei,
• Hidde Stokkel,
• Jian-Yao Zheng,
• Andrea Cerreta,
• Ilka Hermes,
• Minh Nguyen,
• Guus Rijnders and
• Rebecca Saive

Beilstein J. Nanotechnol. 2023, 14, 1059–1067, doi:10.3762/bjnano.14.87

• KPFM shown in Figure 1a illustrates multiple lock-in amplifiers employed to excite the cantilever both mechanically and electrically at the same time, and to retrieve simultaneously the amplitude and phase of the movement of the cantilever at different frequencies. The cantilever is excited at its

• the cantilever resonance. Modulating the tip with VAC while the cantilever is oscillating near its resonance frequency leads to frequency mixing and intermodulation of the two frequencies (f0 ± fAC) [34]. The lock-in amplifiers 2 and 3 are fed with the vertical deflection signal of the cantilever to

• measure the sideband signals at f0 + fAC and f0 − fAC. Then, their average is used for the KPFM feedback to adjust the DC bias. If fAC is chosen to be small enough, such that the sideband peaks are close to f0, the amplitude of these peaks will be enhanced by the mechanical resonance of the cantilever

Exploring internal structures and properties of terpolymer fibers via real-space characterizations

• Michael R. Roenbeck and
• Kenneth E. Strawhecker

Beilstein J. Nanotechnol. 2023, 14, 1004–1017, doi:10.3762/bjnano.14.83

• N/m (nominal), k = 12–21 N/m (measured)) were used for AFM scans. By simultaneously exciting the AFM cantilever to its first and second resonance (f1 = 160–190 kHz and f2 = 900–1150 kHz, Figure 1c) and applying two distinct control conditions (amplitude modulation (AM) and frequency modulation (FM

• . Dashed line highlights a shear plane between the two notches. The fiber readily opens along this plane, exposing internal fiber surfaces for characterization. (c) Multifrequency AFM schematic. A cantilever is driven by a blue laser that simultaneously excites the cantilever at its first and second

• resonance frequencies (f1 and f2). The response of the cantilever as it scans across the exposed internal fiber surface provides information about the local fiber internal morphology and mechanical response (stiffness and transverse elastic modulus (ET)). Fiber-wide Technora® AFM maps. (a) Topography map

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

• 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

• + dc potential is applied, the KPFM tip scans across a surface. The ac signal is sinusoidal with a frequency that equals the mechanical resonance of the cantilever. The four-quadrant detector gives feedback in order to minimize cantilever oscillation modifying the dc signal providing the sample surface

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

• 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

• vibrating cantilever are A and f0, respectively. The time-varying tip–sample distance is given by From this equation and the relationship Cg = ε0/z, we obtain the following expression: Because of frequency mixing between the electrostatic force due to the AC bias voltage cos 2πfmt and the cantilever

Intermodal coupling spectroscopy of mechanical modes in microcantilevers

• Ioan Ignat,
• Bernhard Schuster,
• Jonas Hafner,
• MinHee Kwon,
• Daniel Platz and
• Ulrich Schmid

Beilstein J. Nanotechnol. 2023, 14, 123–132, doi:10.3762/bjnano.14.13

• opportunity to bring intermodal coupling techniques, derived from optomechanics, to AFM. It is easily accessible, with no hardware modifications and only requiring multifrequency excitation applied to the cantilever by either a piezoshaker or a modulated laser, found in many AFM setups. The field of

• excitation of the first mode of a cantilever with measurements being performed at its harmonics [37]. Another method involved clever designs such as T-shaped cantilevers [38] and inner-paddled cantilevers [39] aiming at reducing the noise impact on force reconstruction. Bimodal AFM is another addition to the

• field, where two eigenmodes are excited and read simultaneously [40]. Last, intermodulation products, created by two signals close to the fundamental cantilever mode, form a sea of evenly spaced tones to be measured [35][41][42]. All of these rely on the nonlinear tip–surface force to create these

Characterisation of a micrometer-scale active plasmonic element by means of complementary computational and experimental methods

• Ciarán Barron,
• Giulia Di Fazio,
• Samuel Kenny,
• Silas O’Toole,
• Robin O’Reilly and
• Dominic Zerulla

Beilstein J. Nanotechnol. 2023, 14, 110–122, doi:10.3762/bjnano.14.12

• plasmonic response. This heating also results in thermal expansion of the element. This expansion will result in deflection of an AFM cantilever scanning the surface. If a sinusoidal voltage is applied to an electrically conducting sample, such as the active plasmonic element discussed here, the resulting

• nanomechanical operations such as lithography and machining. The high spring constant of this cantilever has the advantage of minimising the unwanted deflection of the cantilever resulting from electrostatic interaction of the potential on the surface and the probe. The tip is constructed from wear-resistant

• Cypher AFM. This frequency is also well below the resonance frequency of the selected cantilever avoiding unwanted resonant oscillations in the cantilever as a result of the periodic force applied by the expanding surface when deflecting the cantilever. In principle, the drive frequency of the active

Frequency-dependent nanomechanical profiling for medical diagnosis

• Santiago D. Solares and
• Alexander X. Cartagena-Rivera

Beilstein J. Nanotechnol. 2022, 13, 1483–1489, doi:10.3762/bjnano.13.122

• optical imaging, the device could be equipped with one or more piezoelectrically excited membranes coupled with a sensing mechanism, such as an AFM cantilever or other type of mechanical sensor (similar stand-alone developments already exist [31][32]). The mechanical response of the membrane could be

Studies of probe tip materials by atomic force microscopy: a review

• Ke Xu and
• Yuzhe Liu

Beilstein J. Nanotechnol. 2022, 13, 1256–1267, doi:10.3762/bjnano.13.104

• . Applications range from mechanical and electrical sample characterization to measurements in liquids [1][2][3][4] and even in living cells [5][6][7][8]. The critical element of an AFM is the scanning probe itself, which is usually represented by a micro-cantilever beam equipped with a conical scanning tip. As

• the tip approaches the sample surface, an interaction force is generated that deflects (bends or stretches) the probe cantilever. As the AFM probe moves across the sample surface (in the X and Y directions), morphological information is obtained over the entire scan area. Its tip structure and the

• mechanical properties of the cantilever beam directly affect the performance, measurement resolution, and image quality of the AFM instrument. AFM probe tips [9][10] are generally fabricated with coatings, carbon nanotubes, magnetic nanoparticles, or even protein functionalization. A combination of probe

A cantilever-based, ultrahigh-vacuum, low-temperature scanning probe instrument for multidimensional scanning force microscopy

• Hao Liu,
• Zuned Ahmed,
• Sasa Vranjkovic,
• Manfred Parschau,
• Andrada-Oana Mandru and
• Hans J. Hug

Beilstein J. Nanotechnol. 2022, 13, 1120–1140, doi:10.3762/bjnano.13.95

• Cantilever-based atomic force microscopy (AFM) performed under ambient conditions has become an important tool to characterize new material systems as well as devices. Current instruments permit robust scanning over large areas, atomic-scale lateral resolution, and the characterization of various sample

• tuning fork force sensor became increasingly popular. In comparison to microfabricated cantilevers, the more macroscopic tuning forks, however, lack sensitivity, which limits the measurement bandwidth. Moreover, multimodal and multifrequency techniques, such as those available in cantilever-based AFM

• carried out under ambient conditions, are challenging to implement. In this article, we describe a cantilever-based low-temperature UHV AFM setup that allows one to transfer the versatile AFM techniques developed for ambient conditions to UHV and low-temperature conditions. We demonstrate that such a

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

• first two eigenmodes of the cantilever. These comparisons allow the reader to quickly and quantitatively identify the parameters for the best performance for a given KPFM-based experiment in a given environment. Furthermore, we apply these performance metrics in the identification of KPFM-based modes

• forces in KPFM is generally expressed as the minimum detectable CPD [53], and is directly limited by the geometry of the interaction, thermal noise of the cantilever, and the detection noise limits of the AFM [36][54]. Cantilevers have a number of eigenmodes, ωn, where there is a mechanical enhancement

• to ωn where ∝ Qn/kn and there is a significant enhancement in the oscillation amplitude of the cantilever in response to the electrostatic force, thereby increasing the signal-to-noise ratio (SNR) [10]. In this paper we define the SNR as the ratio of the measured signal (oscillation amplitude of the

Temperature and chemical effects on the interfacial energy between a Ga–In–Sn eutectic liquid alloy and nanoscopic asperities

• Yujin Han,
• Pierre-Marie Thebault,
• Corentin Audes,
• Xuelin Wang,
• Haiwoong Park,
• Jian-Zhong Jiang and
• Arnaud Caron

Beilstein J. Nanotechnol. 2022, 13, 817–827, doi:10.3762/bjnano.13.72

• force–distance curve with each cantilever on a quartz glass sample (manufactured by Goodfellow, United Kingdom) and extracting its slope in the range of repulsive forces. Subsequently, we determined the bending stiffness Cn of each cantilever by analyzing its thermal noise vibration [18]. After

• consisted of approaching a cantilever towards the sample surface at varying velocities dZ/dt = 0.1–25 µm/s (see Figure 1). We repeated force spectroscopy measurements at each approach/retraction velocity 15 times. We used the retraction part of the force–distance curves to determine the adhesion force Fad

• hysteresis for the normal force is not as straightforward to explain. In our experiments, we can exclude the effect of crosstalk due to misalignment of the cantilever since we mounted each cantilever on the same alignment chip on the cantilever holder. We consider it more likely that the hysteresis of the

Optimizing PMMA solutions to suppress contamination in the transfer of CVD graphene for batch production

• Chun-Da Liao,
• Andrea Capasso,
• Tiago Queirós,
• Telma Domingues,
• Fatima Cerqueira,
• Nicoleta Nicoara,
• Jérôme Borme,
• Paulo Freitas and
• Pedro Alpuim

Beilstein J. Nanotechnol. 2022, 13, 796–806, doi:10.3762/bjnano.13.70

• frequency. The AFM measurement was carried out in tapping mode. A 633 nm laser light aimed at the back side of the cantilever tip was reflected toward a position-sensitive photodetector, which provides feedback signals to piezoelectric scanners that maintain the cantilever tip at constant height (force