Routes to rupture and folding of graphene on rough 6H-SiC(0001) and their identification

• M. Temmen,
• O. Ochedowski,
• B. Kleine Bussmann,
• M. Schleberger,
• M. Reichling and
• T. R. J. Bollmann

Beilstein J. Nanotechnol. 2013, 4, 625–631, doi:10.3762/bjnano.4.69

• . Peeling at a folding over an edge different from a low index crystallographic direction can result in twisted BLG, showing a similar height as Bernal (or AA-stacked) BLG in NC-AFM images. The rotational stacking can be identified by a significant contrast in the local contact potential difference (LCPD

• ) measured by KPFM. Keywords: graphene; Kelvin probe force microscopy (KPFM), local contact potential difference (LCPD); non-contact atomic force microscopy (NC-AFM); SiC; Introduction Since its discovery in 2004 [1], graphene, the 2D crystal with a honeycomb lattice of sp2-bonded carbon atoms, has been

• different BLG stackings, we investigate the topography by non-contact atomic force microscopy (NC-AFM) combined with measuring the local contact potential differences (LCPD) using Kelvin probe force microscopy (KPFM). Experimental Graphene is exfoliated from a HOPG crystal (Momentive Performance Materials

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

• -potential detection method that determines the contact potential difference (CPD) during scanning by compensating the electrostatic forces between a microscopic tip and the sample [34]. Figure 2a illustrates a schematic band diagram for a KPFM tip in close proximity to a semiconductor sample surface with

Dipole-driven self-organization of zwitterionic molecules on alkali halide surfaces

• Laurent Nony,
• Franck Bocquet,
• Franck Para,
• Frédéric Chérioux,
• Eric Duverger,
• Frank Palmino,
• Vincent Luzet and
• Christian Loppacher

Beilstein J. Nanotechnol. 2012, 3, 285–293, doi:10.3762/bjnano.3.32

• oscillation feedback controller and the topography is regulated by keeping the frequency shift Δf constant. The contact potential difference between the tip and the sample was compensated by applying the corresponding bias voltage to the tip (static, no feedback). For image evaluation we used the WSxM

Junction formation of Cu₃BiS₃ investigated by Kelvin probe force microscopy and surface photovoltage measurements

• Fredy Mesa,
• William Chamorro,
• William Vallejo,
• Robert Baier,
• Thomas Dittrich,
• Alexander Grimm,
• Martha C. Lux-Steiner and
• Sascha Sadewasser

Beilstein J. Nanotechnol. 2012, 3, 277–284, doi:10.3762/bjnano.3.31

• <10−10 mbar [25], by using the amplitude-modulation technique (AM mode). We used PtIr-coated cantilevers (Nanosensors) with a first resonance frequency of ~75 kHz, measuring the contact potential difference (CPD) using the second resonance mode at ~450 kHz and an ac voltage of 100 mV. For detection of

A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope

• Manfred Lange,
• Dennis van Vörden and
• Rolf Möller

Beilstein J. Nanotechnol. 2012, 3, 207–212, doi:10.3762/bjnano.3.23

• the drawing of the molecule. In order to compensate the electrostatic long-range forces, frequency-shift versus bias-voltage curves were recorded on the PTCDA herringbone island, revealing a contact potential difference of 0.1 V. By adjusting the bias voltage to this value the electrostatic long-range

Noncontact atomic force microscopy study of the spinel MgAl₂O₄(111) surface

• Morten K. Rasmussen,
• Kristoffer Meinander,
• Flemming Besenbacher and
• Jeppe V. Lauritsen

Beilstein J. Nanotechnol. 2012, 3, 192–197, doi:10.3762/bjnano.3.21

• scanning the surface. The surface potential, measured after annealing the crystal, was generally quite high, often in the range 4–8 V. Therefore, the voltage applied between the surface and the tip, Ubias, was monitored and adjusted regularly to minimize the electrostatic forces arising from the contact

• potential difference. (a) Ball model of the MgAl2O4 stacking sequence in the [111] direction showing one repeat unit of 4.67 Å in height. (b–g) The hexagonal patches show six ball models, which illustrate the possible surfaces obtained from a bulk-truncation of the sequence in (a). Experimental NC-AFM

Quantitative multichannel NC-AFM data analysis of graphene growth on SiC(0001)

• Christian Held,
• Thomas Seyller and
• Roland Bennewitz

Beilstein J. Nanotechnol. 2012, 3, 179–185, doi:10.3762/bjnano.3.19

• to several complementary signals, such as topography, damping, and contact potential. The traditional presentation of such data sets in adjacent figures or in colour-coded pseudo-three-dimensional plots gives only a qualitative impression. We introduce two-dimensional histograms for the

• representation of multichannel NC-AFM data sets in a quantitative fashion. Presentation and analysis are exemplified for topography and contact-potential data for graphene grown epitaxially on 6H-SiC(0001), as recorded by Kelvin probe force microscopy in ultrahigh vacuum. Sample preparations by thermal

• identification of the graphene layer thickness from the local contact potential as determined by means of Kelvin probe force microscopy (KPFM) [11][12]. As a further advantage, KPFM determines step heights more accurately than STM or AFM with constant bias [13] and is therefore employed in this study to

qPlus magnetic force microscopy in frequency-modulation mode with millihertz resolution

• Maximilian Schneiderbauer,
• Daniel Wastl and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2012, 3, 174–178, doi:10.3762/bjnano.3.18

• compensated for the contact potential difference (CPD) in both paths. We determined the CPD by taking Kelvin parabolas over the sample surface; typical values are 250 mV. The Nanonis Multipass configuration also allows us to vary the scan speed on different paths. For the second path, in which the frequency

Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100) at 5 K: Probing the probe

• Adam Sweetman,
• Sam Jarvis,
• Rosanna Danza and
• Philip Moriarty

Beilstein J. Nanotechnol. 2012, 3, 25–32, doi:10.3762/bjnano.3.3

• , the probe [14] (especially the influence of tunnelling electrons during STM). While in principle NC-AFM can provide a “cleaner” system (i.e., imaging is possible without the presence of tunnelling electrons), a bias is often applied to null out the contact-potential difference (CPD) between tip and

Distinguishing magnetic and electrostatic interactions by a Kelvin probe force microscopy–magnetic force microscopy combination

• Miriam Jaafar,
• Oscar Iglesias-Freire,
• Luis Serrano-Ramón,
• Manuel Ricardo Ibarra,
• Jose Maria de Teresa and
• Agustina Asenjo

Beilstein J. Nanotechnol. 2011, 2, 552–560, doi:10.3762/bjnano.2.59

• of an oxide layer 2 nm thick and a contact potential between tip and sample of 1 V [25]. We calculate the magnetic interaction of two Co spheres with a radius of 20 nm. The values in Table 1 show that at short distances all the interactions are on the same order of magnitude, although van der Waals

• between the tip and the sample [43]. The bias voltage at the apexes of those parabolas, measured in different regions of the sample, corresponds to the contact potential between the tip and the selected region of the sample. The respective maxima of the curves in Figure 2c are shifted to about +320 mV

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

• measured contact potential difference even under ultra-high vacuum conditions, and we demonstrate a good agreement between our model and KPFM measurements in ultra-high vacuum of NaCl monolayers grown on Cu(111). The effect of the oscillating cantilever shape on the KPFM resolution and sensitivity has been

• the cantilever has a very strong effect on the absolute value of the measured contact potential difference (CPD) even under UHV conditions, and we demonstrate a good agreement between our model and KPFM measurements. Experimental Electrostatic model In order to calculate the full probe configuration

Single-pass Kelvin force microscopy and dC/dZ measurements in the intermittent contact: applications to polymer materials

• Sergei Magonov and
• John Alexander

Beilstein J. Nanotechnol. 2011, 2, 15–27, doi:10.3762/bjnano.2.2

• response, which is detected by the phase signal or Y component signal of the LIA-1, is seen at the heterodyne frequencies ωmech ± ωelec. When the KFM servo is on, the heterodyne sidebands practically disappear and the DC voltage equals the contact potential difference. This AM–FM procedure is similar to

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

• Thomas König,
• Georg H. Simon,
• Lars Heinke,
• Leonid Lichtenstein and
• Markus Heyde

Beilstein J. Nanotechnol. 2011, 2, 1–14, doi:10.3762/bjnano.2.1

• surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001) and line defects in aluminum oxide on NiAl(110), respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM) and the electronic structure by scanning

• tunneling spectroscopy (STS). On magnesium oxide, different color centers, i.e., F0, F+, F2+ and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in

• aluminum oxide. At these domain boundaries, STS and KPFM verify F2+-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully