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

• actuating the cantilever results in a frequency response free of spurious peaks. We analyze static, harmonic, and sub-harmonic actuation modes. Sub-harmonic mode results in stable amplitudes unaffected by potential offsets or fluctuations of the electrical surface potential. We present a simple plate

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

• performed for a variation of dc-bias voltages (to extract the measured VCPD) and for a variation of the period of the modulated bias voltage. While the simulations consider a direct modulation of the sample bias, this can correspond to experimental situations where the sample surface potential is modulated

• by an applied modulated bias, by modulated light pulses, or any other modulation that results in a modulation of the sample surface potential. The numerical simulations only consider a slow Kelvin controller that cannot follow the applied bias modulation and therefore measures an average VCPD. With

• measurements with time resolution down to picoseconds have been developed, many times using a modulated excitation signal, e.g., light modulation or bias modulation that induces changes in the charge carrier distribution. For fast modulation frequencies, the KPFM controller measures an average surface

Electro-optical interfacial effects on a graphene/π-conjugated organic semiconductor hybrid system

• Karolline A. S. Araujo,
• Luiz A. Cury,
• Matheus J. S. Matos,
• Thales F. D. Fernandes,
• Luiz G. Cançado and
• Bernardo R. A. Neves

Beilstein J. Nanotechnol. 2018, 9, 963–974, doi:10.3762/bjnano.9.90

• surface potential changes on the hybrid system. In summary, interface-induced organized structures atop 2D materials may have an important impact on both design and operation of π-conjugated nanomaterial-based hybrid systems. Keywords: DFT calculations; graphene; organic semiconductors; scanning probe

• modeled by where, ω0 and k are the cantilever’s resonant frequency and spring constant, respectively, C´´(z) is the second derivative of the tip–sample capacitance C(z), Vtip is the applied bias, Φ is the tip–sample surface potential difference, and f´(z) is the first derivative of the electric force

• region of the image is proportional to the dielectric constant of the material underneath the EFM tip, surface potential differences and to any accumulated charges/permanent polarization at the surface [34]. Equation 2 was used to fit all experimental data in Figure 4c–e (blue or brown solid lines in

The nanofluidic confinement apparatus: studying confinement-dependent nanoparticle behavior and diffusion

• Stefan Fringes,
• Felix Holzner and
• Armin W. Knoll

Beilstein J. Nanotechnol. 2018, 9, 301–310, doi:10.3762/bjnano.9.30

• increase adhesion for the subsequently spin coated 175 ± 2 nm thick poly-phthalaldehyde (PPA) film. The thicknesses were measured with AFM. The refractive indices nHM = 1.67 and nPPA = 1.59 were measured by ellipsometry. The surface potential of PPA in 1 mM KCl solution (pH 7–7.5) was measured in a Malvern

• sphere, respectively. In this linear approximation the overall interaction energy of a sphere between two walls is obtained by the sum of the interaction energies to each wall. Assuming a surface potential of the sphere of −58 mV (see methods) and a surface potential of the walls of −67 mV as determined

• diffusion. We note, however, that the same effect could be induced by a charge modulation of the surface potential (or correspondingly the surface charge) by ≈5%. To further investigate the origin of the obstacles we analyzed the time-averaged lateral particle distribution and its correlation to 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

•  1), adsorbed on an atomically clean NiO(001) crystal surface. It adsorbs either as single molecule or forms specific assemblies increasing in size from small clusters up to complete islands inducing a clear change of the surface potential. Results and Discussion Atomic resolution of NiO(001) Figure

Combined scanning probe electronic and thermal characterization of an indium arsenide nanowire

• Tino Wagner,
• Fabian Menges,
• Heike Riel,
• Bernd Gotsmann and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2018, 9, 129–136, doi:10.3762/bjnano.9.15

• complementary information obtained by KFM. Figure 2a shows our setup for KFM measurements. The nanowire is driven by a dc voltage bias and the two-terminal current is inferred from the voltage drop across a 100 kΩ shunt resistor. For accurate surface potential measurements and to minimize the effect of long

• topography and surface potential obtained on the same InAs nanowire as shown in Figure 1. Owing to the particular KFM detection method, we do not observe long-range lateral averaging of the surface potential, and the nanowire and electrodes appear well defined. We recorded surface potential profiles along

• the centre of the nanowire during consecutive sweeps of the voltage bias. The two-terminal current thereby assumed 50 different values between −38 and +38 μA for each sweep, and several lines were recorded and averaged for each constant bias. The measured surface potential is thus a function of

Evaluation of preparation methods for suspended nano-objects on substrates for dimensional measurements by atomic force microscopy

• Petra Fiala,
• Daniel Göhler,
• Benno Wessely,
• Michael Stintz,
• Giovanni Mattia Lazzerini and
• Andrew Yacoot

Beilstein J. Nanotechnol. 2017, 8, 1774–1785, doi:10.3762/bjnano.8.179

• properties (e.g., surface potential of material and substrate, tendency of nano-objects to agglomerate, adhesion force, size and shape). Therefore several preparation methods (membrane filtration, drying, rinsing, dip coating, electrostatic precipitation, thermal precipitation) on silicon (Si) and with

Uptake and intracellular accumulation of diamond nanoparticles – a metabolic and cytotoxic study

• Antonín Brož,
• Lucie Bačáková,
• Pavla Štenclová,
• Alexander Kromka and
• Štěpán Potocký

Beilstein J. Nanotechnol. 2017, 8, 1649–1657, doi:10.3762/bjnano.8.165

• [37]. In this work, we focus on cytotoxicity studies of NDs as a function of their synthesis route (DNDs versus HPHT NDs), their concentration in the medium (from 10 to 1000 mg/mL, 3 to 300 µg/cm2), their size (5 nm DND, 18–210 nm HPHT NDs) and their surface potential/termination (as-received and

• viability and are negatively correlated with the material cytotoxicity. The live-cell imaging method was used for observing the intake of NDs into the cells. The results were evaluated on the basis of particle size, surface potential, surface functional groups, and the concentration of the ND suspension

Analysis and modification of defective surface aggregates on PCDTBT:PCBM solar cell blends using combined Kelvin probe, conductive and bimodal atomic force microscopy

• Hanaul Noh,
• Alfredo J. Diaz and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2017, 8, 579–589, doi:10.3762/bjnano.8.62

• measurements on both the DCB- and CB-cast samples to examine possible surface potential changes due to morphology differences of the PSC active layers. As shown in Figure 1, a clear difference in surface potential is observed, although there is no obvious correlation with the topography channel. The population

• min to evaporate the remaining solvent in the devices. AFM measurements A series of AFM techniques including KPFM, C-AFM and bimodal AFM were combined to study the model PSCs. First, KPFM was used to find the surface aggregates and map surface potential changes due to the structures, then C-AFM was

• used to map local currents with positive and negative tip biases and correlate the currents with the surface potential. Afterwards, bimodal AFM was used to nanomechanically modify the aggregates. This was accomplished through the excitation of a higher cantilever eigenmode, which serves as a force

Template-controlled piezoactivity of ZnO thin films grown via a bioinspired approach

• Nina J. Blumenstein,
• Fabian Streb,
• Stefan Walheim,
• Thomas Schimmel,
• Zaklina Burghard and
• Joachim Bill

Beilstein J. Nanotechnol. 2017, 8, 296–303, doi:10.3762/bjnano.8.32

• substrate and particles in the solution and therefore, the interaction between both is affected. For example it was found that silica shows a decreasing surface potential if methanol is added to an aqueous electrolyte solution [41][42]. This can be explained by the lower ability of methanol to stabilize

Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors

• Elena Dilonardo,
• Michele Penza,
• Marco Alvisi,
• Gennaro Cassano,
• Cinzia Di Franco,
• Francesco Palmisano,
• Luisa Torsi and
• Nicola Cioffi

Beilstein J. Nanotechnol. 2017, 8, 82–90, doi:10.3762/bjnano.8.9

• , causing changes in the surface potential and resistivity of the sensing material. The electrical resistance can increase or decrease, depending on the type of doping of MOx (p- or n-type) and on the analyte gas. There are oxidizing gases, such as nitrogen oxide (NO2), and ozone (O3), and reducing gases

Metal oxide-graphene field-effect transistor: interface trap density extraction model

• Faraz Najam,
• Kah Cheong Lau,
• Cheng Siong Lim,
• Yun Seop Yu and
• Michael Loong Peng Tan

Beilstein J. Nanotechnol. 2016, 7, 1368–1376, doi:10.3762/bjnano.7.128

• parameters calculated using the extracted interface trap distribution from the model, including surface potential, interface trap charge and interface trap capacitance compared very well with their respective experimental counterparts. The model enables accurate calculation of the surface potential affected

• by trap charge. Other models ignore the effect of trap charge and only calculate the ideal surface potential. Such ideal surface potential when used in a surface potential based drain current model will result in an inaccurate prediction of the drain current. Accurate calculation of surface potential

• that can later be used in drain current model is highlighted as a major advantage of the model. Keywords: drain current compact model; interface trap distribution; metal-oxide-graphene field-effect transistor (MOGFET); surface potential; Introduction Graphene has recently attracted a lot of attention

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

• simultaneously probe the nanostructure and the optoelectronic properties of organic and hybrid, photoactive thin films and devices [3][4][5][6][7][8][9]. Particularly, the local surface photo-voltage (SPV) of organic blends [3][4][6][7] can be mapped in KPFM by analysing the surface potential (or contact

• contact potential difference (CPD) is equal to −VDC. In this work, the potentiometric data are presented as compensation bias (Vtip = −CPD) images (also called CPD images, KPFM potential or surface potential images). Surface photo-voltage (SPV) images were calculated as the difference between the

• mesoscopic scale (Figure 7), it can be clearly seen that the surface potential shifts downwards upon illumination, resulting in a negative surface photo-voltage. The potential shift is completely reversible (Figure S4 in Supporting Information File 1), revealing the absence of permanent charge trapping

3D solid supported inter-polyelectrolyte complexes obtained by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate)

• Eduardo Guzmán,
• Armando Maestro,
• Sara Llamas,
• Jesús Álvarez-Rodríguez,
• Francisco Ortega,
• Ángel Maroto-Valiente and
• Ramón G. Rubio

Beilstein J. Nanotechnol. 2016, 7, 197–208, doi:10.3762/bjnano.7.18

• ). Surface potential measurements A Kelvin probe from Trek, Inc. (U.K.), located approximately 2 mm above the substrate, was used in order to measure the surface potential (ΔV) of the multilayer in the dry state after each cycle of deposition. The surface potential measurements are referenced to the value of

• traditionally considered as the main driving force for the assembly of polyelectrolyte films obtained by LbL methods [16][55]. In order to evaluate the charge inversion due to the sequential adsorption of layers with opposite charge, measurements of the changes of the surface potential, ΔV, have been performed

• (Figure 8a). The surface potential value changes between positive and negative values for the alternated adsorption of polycation and polyanion layers, respectively. Note that even the changes of the surface potential with N are similar to those expected for the ζ-potential; the absolute values measured

pH-Triggered release from surface-modified poly(lactic-co-glycolic acid) nanoparticles

• Manuel Häuser,
• Klaus Langer and
• Monika Schönhoff

Beilstein J. Nanotechnol. 2015, 6, 2504–2512, doi:10.3762/bjnano.6.260

• directly correlated to the pH of PAA during adsorption. In case of the titration curves obtained for PAA adsorbed at pH 5 and pH 7, respectively, a decrease of surface potential is observed after reaching its maximum value (see Figure 2). This can be attributed to surface charge compensation effects

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

• features can be observed in the line sections shown in Figure 7a. At the p/n-junction a dip in the CPD can be observed which vanishes under illumination. This might indicated that the interface states are already fully charged before illumination inducing a dip in the surface potential. Furthermore, the

• Wtheo = 570 nm that is analytically calculated through Equation 1 and Equation 3 [57]. A much longer decay of the surface potential was also observed by M. Gao et al. in locally resolved secondary electron emission measurements across a SiC p/n-junction [44]. They attributed the increase of the SCR to

• presented in Figure 9d. The value of NA = 4 × 1016 cm−2 is reasonable and under the assumption that only the built-in voltage changes from the surface towards the bulk one calculates a bulk concentration of NA = 4 × 1017 cm−2 for an estimated built-in voltage of 3 V. Therefore, the change of the surface

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

• lateral resolution and pronounced capacitive averaging of the locally measured contact potential difference. Furthermore, local changes in the strength of the electrostatic interaction between tip and surface easily lead to topography crosstalk seen in the surface potential. To take full advantage of the

• surface state density and Schottky depletion region in semiconductor nanowires [4][5] or to determine the mean free path in carbon nanotubes [6]. KFM also allows one to determine intrinsic doping of two-dimensional crystals such as graphene [7][8], where surface potential and electronic properties depend

• surface potential measurements include deconvolution techniques [11][12] or the use of slightly blunt tips supported by a cantilever of minimal surface area [9]. However, deconvolution techniques require a detailed model of the AFM tip to be accurate and usually neglect the sample topography [12], whereas

Electrospray deposition of organic molecules on bulk insulator surfaces

• Antoine Hinaut,
• Rémy Pawlak,
• Ernst Meyer and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2015, 6, 1927–1934, doi:10.3762/bjnano.6.195

• positive charging of the surface is in agreement with the estimated large negative bias voltages needed to compensate the surface potential of approximately −30 V. A major disadvantage of UHV-ESI for insulating surfaces is thus the surface charging of the crystals, increasing with the deposition time and

Temperature-dependent breakdown of hydrogen peroxide-treated ZnO and TiO₂ nanoparticle agglomerates

• Sinan Sabuncu and
• Mustafa Çulha

Beilstein J. Nanotechnol. 2015, 6, 1897–1903, doi:10.3762/bjnano.6.193

• nm) was examined [16]. The thermal conductivity and surface potential of the nanofluids were also studied [17][18][19]. The toxicity of NPs is another concern that is strongly related to their size, shape, and surface chemistry. Since the synthesis of NPs of a certain size and shape in large

Protein corona – from molecular adsorption to physiological complexity

• Lennart Treuel,
• Dominic Docter,
• Michael Maskos and
• Roland H. Stauber

Beilstein J. Nanotechnol. 2015, 6, 857–873, doi:10.3762/bjnano.6.88

• acid (DHLA)-coated quantum dots (QDs) by using fluorescence correlation spectroscopy (FCS) [4]. The electrostatic surface potential of native HSA shows distinct, positively charged patches on an otherwise negative potential surface (Figure 3). These patches are caused by the presence of basic lysine

Stick–slip behaviour on Au(111) with adsorption of copper and sulfate

• Nikolay Podgaynyy,
• Sabine Wezisla,
• Christoph Molls,
• Shahid Iqbal and
• Helmut Baltruschat

Beilstein J. Nanotechnol. 2015, 6, 820–830, doi:10.3762/bjnano.6.85

• force exceeds a certain threshold [18]. The behaviour of water on crystalline surfaces was described as a viscous structure, which can resist to the tip pressure up to 4 water layers [19]. On the other hand, the properties of viscous water on a gold surface are dependent on the surface potential. For Au

Fundamental edge broadening effects during focused electron beam induced nanosynthesis

• Roland Schmied,
• Jason D. Fowlkes,
• Robert Winkler,
• Phillip D. Rack and
• Harald Plank

Beilstein J. Nanotechnol. 2015, 6, 462–471, doi:10.3762/bjnano.6.47

• explanation. Functionality In the following a two-step approach is followed: First, the surface potential, which reflects the chemical composition and its electronic properties, and, subsequently, the electric conductivity are mapped. The combination of both measurements allows one then to derive the scaling

• resolved measurement of the variations in surface potential. Figure 3 gives a representative AFM height image (a) together with the corresponding surface potential (b) of a ca. 9 nm thick deposit fabricated at 25 keV. Correlated cross sections are shown in Figure 3c for the height (top), the tapping phase

• (center, green), and the surface potential (bottom, blue). As can be seen the surface potential reveals three different levels: 1) the SiO2 substrate (offset to zero); 2) the deposit with a potential difference of about −150 mV; and 3) another level for the outer halo at −300 mV. The essential information

Kelvin probe force microscopy in liquid using electrochemical force microscopy

• Liam Collins,
• Stephen Jesse,
• Jason I. Kilpatrick,
• Alexander Tselev,
• M. Baris Okatan,
• Sergei V. Kalinin and
• Brian J. Rodriguez

Beilstein J. Nanotechnol. 2015, 6, 201–214, doi:10.3762/bjnano.6.19

• [18], electrochemical [19] and ionic [15] functionality on the nanoscale have been developed. A paradigmatic example of such development is closed loop-Kelvin probe force microscopy (KPFM) [20], which has become a widely used voltage-modulated SPM technique for the measurement of surface potential

• ionic materials [14][28][29]. When operated in ultra-high vacuum, KPFM has been demonstrated to provide absolute surface potential measurements, with molecular and atomic scale resolution previously reported [30][31][32]. Interpretation of surface potential values from this technique can, however

• , become complicated by feedback artefacts and stray capacitance even in vacuum [33][34][35]. In ambient environments, the interpretation of surface potential values increases in complexity due to the possible shielding of the surface by mobile adsorbates and the presence of a thin water layer, resulting

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state

• Florian G. Strobl,
• Florian Seitz,
• Christoph Westerhausen,
• Armin Reller,
• Adriano A. Torrano,
• Christoph Bräuchle,
• Achim Wixforth and
• Matthias F. Schneider

Beilstein J. Nanotechnol. 2014, 5, 2468–2478, doi:10.3762/bjnano.5.256

• . The ζ-potential is inserted for the relevant surface potential, as also proposed in [33]. In Figure 4, gdl is plotted for ζ = −50 mV and l = 1.72 nm and εr = 79, corresponding to our experimental conditions. Additionally, an approximation for the non-retarded van der Waals interaction is given (see

Interaction of dermatologically relevant nanoparticles with skin cells and skin

• Annika Vogt,
• Fiorenza Rancan,
• Sebastian Ahlberg,
• Berouz Nazemi,
• Chun Sik Choe,
• Maxim E. Darvin,
• Sabrina Hadam,
• Ulrike Blume-Peytavi,
• Kateryna Loza,
• Jörg Diendorf,
• Matthias Epple,
• Christina Graf,
• Eckart Rühl,
• Martina C. Meinke and
• Jürgen Lademann

Beilstein J. Nanotechnol. 2014, 5, 2363–2373, doi:10.3762/bjnano.5.245

• functionalization of silica particles with amino groups in order to turn the surface potential of the particles from initially negative to highly positive did not significantly affect cellular uptake rates in whole-tissue experiments. However, immortalized human keratinocytes (HaCaT, Human Adult Low Calcium High