Reduced subthreshold swing in a vertical tunnel FET using a low-work-function live metal strip and a low-k material at the drain

• Kalai Selvi Kanagarajan and
• Dhanalakshmi Krishnan Sadhasivan

Beilstein J. Nanotechnol. 2024, 15, 713–718, doi:10.3762/bjnano.15.59

• barrier width enhances electron transfer in the on-state. Leakage current in the off-state is reduced by a wide tunneling barrier. Subthreshold swing The gate dielectric material and the geometry of the transistor help in reducing the subthreshold swing. The subthreshold swing is 5 mV/dec for VTFET with

Unveiling the nature of atomic defects in graphene on a metal surface

• Karl Rothe,
• Nicolas Néel and
• Jörg Kröger

Beilstein J. Nanotechnol. 2024, 15, 416–425, doi:10.3762/bjnano.15.37

• retraction (I↑) current data, albeit with a smaller width of the hysteresis loop. The onset of deviations of I↓ from a uniform exponential increase, marked Δzc in the inset to Figure 5f, signals the collapse of the tunneling barrier and the formation of a chemical bond between the tip and the surface [32][36

Ultrasensitive and ultrastretchable metal crack strain sensor based on helical polydimethylsiloxane

• Shangbi Chen,
• Dewen Liu,
• Weiwei Chen,
• Huajiang Chen,
• Jiawei Li and
• Jinfang Wang

Beilstein J. Nanotechnol. 2024, 15, 270–278, doi:10.3762/bjnano.15.25

• strain, can be described by the following formula: When the strain ε is small, we can formulate: where X is the tunneling barrier height-dependent function. Figure 2b shows the good linearity between measured resistance and strain; the curves fit quite well to the analytical solution. When the helical

Efficiency of electron cooling in cold-electron bolometers with traps

• Dmitrii A. Pimanov,
• Vladimir A. Frost,
• Anton V. Blagodatkin,
• Anna V. Gordeeva,
• Andrey L. Pankratov and
• Leonid S. Kuzmin

Beilstein J. Nanotechnol. 2022, 13, 896–901, doi:10.3762/bjnano.13.80

• tunneling barrier of the NIS junctions and smaller single-particle and double-particle components of the current. For sample C, the normal resistance per one NIS junction is 1.3 kΩ, and for sample OL-G7nn this resistance is 6.4 kΩ. These differences can be seen in the electron temperature graphs: For the

Scanning tunneling microscopy and spectroscopy of rubrene on clean and graphene-covered metal surfaces

• Karl Rothe,
• Alexander Mehler,
• Nicolas Néel and
• Jörg Kröger

Beilstein J. Nanotechnol. 2020, 11, 1157–1167, doi:10.3762/bjnano.11.100

• by sinusoidally modulating the bias voltage (5 mVrms, 750 Hz) and measuring the first harmonic of the current response of the tunneling barrier. Results and Discussion Pt(111)–C42H28 Figure 2a shows an overview STM image of C42H28 on Pt(111) at a coverage of approx. 20%. Well separated molecules or

• states. The presented data were normalized by taking the exponential transmission factor of the tunneling barrier into account [38]. The normalized dI/dV data show a peak at approx. 2.3 V. Due to the considerably broad onset of dI/dV data starting from approx. 1 V it is difficult to unambiguously assign

Anomalous current–voltage characteristics of SFIFS Josephson junctions with weak ferromagnetic interlayers

• Tairzhan Karabassov,
• Anastasia V. Guravova,
• Aleksei Yu. Kuzin,
• Elena A. Kazakova,
• Shiro Kawabata,
• Boris G. Lvov and
• Andrey S. Vasenko

Beilstein J. Nanotechnol. 2020, 11, 252–262, doi:10.3762/bjnano.11.19

• technique, which has been developed to describe many-body systems in equilibrium at finite temperature [92]. In our model the tunneling barrier is located between two F layers at x = 0 (Figure 1), whereas the other interfaces at x = −df1 and x = df2 are identical and transparent. This case corresponds to

Molecular attachment to a microscope tip: inelastic tunneling, Kondo screening, and thermopower

• Rouzhaji Tuerhong,
• Mauro Boero and
• Jean-Pierre Bucher

Beilstein J. Nanotechnol. 2019, 10, 1243–1250, doi:10.3762/bjnano.10.124

• gaps where the tunneling barrier asymmetry at the STM–molecule junction becomes less critical. This asymmetry in the spectrum may suggest that two different vibration-assisted electron-transfer processes apparently compete, one involving a vibration-mediated Kondo effect, and the other, an inelastic

Apparent tunneling barrier height and local work function of atomic arrays

• Neda Noei,
• Alexander Weismann and
• Richard Berndt

Beilstein J. Nanotechnol. 2018, 9, 3048–3052, doi:10.3762/bjnano.9.283

• Neda Noei Alexander Weismann Richard Berndt Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany 10.3762/bjnano.9.283 Abstract Spatially resolved measurements of the apparent tunneling barrier height Φapp in scanning tunneling microscopy

• filament and, consequently, on the local surface structure. Keywords: scanning tunneling microscopy; tunneling barrier height; work function; Findings The work function of a metal surface [1], the work required at temperature T = 0 K to move an electron from the metal to infinity, is relevant for, e.g

Electromigrated electrical optical antennas for transducing electrons and photons at the nanoscale

• Arindam Dasgupta,
• Mickaël Buret,
• Nicolas Cazier,
• Marie-Maxime Mennemanteuil,
• Reinaldo Chacon,
• Kamal Hammani,
• Jean-Claude Weeber,
• Juan Arocas,
• Laurent Markey,
• Gérard Colas des Francs,
• Alexander Uskov,
• Igor Smetanin and
• Alexandre Bouhelier

Beilstein J. Nanotechnol. 2018, 9, 1964–1976, doi:10.3762/bjnano.9.187

• optical antenna primarily consists of measuring the current-to-voltage characteristics IT(Vdc). An example is illustrated in Figure 3a. In this graph, the current density (JT = IT/A) is displayed for an arbitrary tunneling junction area A, chosen at 100 nm2. For a tunneling barrier subject to a small

•  4. The dependence of the transition voltage on is clearly revealed from the graph, demonstrating that Vt cannot be an estimate of the tunneling barrier height. Even if the Fowler–Nordheim plot of the device shown in Figure 4a feature a symmetric transition voltage with respect to the bias

The role of the Ge mole fraction in improving the performance of a nanoscale junctionless tunneling FET: concept and scaling capability

• Hichem Ferhati,
• Fayçal Djeffal and
• Toufik Bentrcia

Beilstein J. Nanotechnol. 2018, 9, 1856–1862, doi:10.3762/bjnano.9.177

• exhibits better electrostatic behavior and less parasitic ambipolar conduction than the other designs. In fact, this behavior can be attributed to two essential effects: Firstly, the enhanced tunneling current resulting from the low tunneling barrier giving rise to a higher probability of electron transfer

• at the source/channel interface. Secondly, the heterostructure at the channel/drain interface can be beneficial for sufficiently enlarging the tunneling barrier under reverse-bias conditions in order to effectively suppress the undesired ambipolar conduction. Moreover, we can notice that the

• tunneling barrier width at the source/channel junction by varying the Ge concentration. Figure 3a shows the transfer characteristics associated of the proposed Si1−xGex/Si/Ge DG-HJ-JL TFET design with different Ge mole fractions. Increasing the Ge content leads to an increase of the drain current. This is

Spatial Rabi oscillations between Majorana bound states and quantum dots

• Jun-Hui Zheng,
• Dao-Xin Yao and
• Zhi Wang

Beilstein J. Nanotechnol. 2018, 9, 1527–1535, doi:10.3762/bjnano.9.143

• an oscillating tunneling strength T = T0 + 2T1cosωt, with T0 being the static tunneling strength, T1 the oscillating tunneling strength, and ω the oscillating frequency for the tunneling strength. It can be produced by an ac gate voltage controlling the tunneling barrier [39]. When the driving

Anodization-based process for the fabrication of all niobium nitride Josephson junction structures

• Massimiliano Lucci,
• Ivano Ottaviani,
• Matteo Cirillo,
• Fabio De Matteis,
• Roberto Francini,
• Vittorio Merlo and
• Ivan Davoli

Beilstein J. Nanotechnol. 2017, 8, 539–546, doi:10.3762/bjnano.8.58

• growth of NbN/AlN/NbN tunnel junctions on oxidized silicon substrates can give rise to a non-optimal barrier formation. In order to check the influence of the substrate on trilayers we plan to test our trilayer process on MgO substrates, which are known, for providing the highest quality of the tunneling

• barrier [13]. We are not sure, however, that the nature of the substrate is the only crucial factor in fabricating NbN-based tunnel junctions with excellent quality. We have shown indeed that an acceptable (in terms of results) NbN process can be obtained just by lift-off lithography and anodization of

Analysis of self-heating of thermally assisted spin-transfer torque magnetic random access memory

• Austin Deschenes,
• Sadid Muneer,
• Mustafa Akbulut,
• Ali Gokirmak and
• Helena Silva

Beilstein J. Nanotechnol. 2016, 7, 1676–1683, doi:10.3762/bjnano.7.160

• contributions from Equation 3 and Equation 4 are released or absorbed on the appropriate side of the tunneling barrier depending on the current polarity. The MRAM device modeled (Figure 1) is composed of the following layers: contact | 0.5 Ta | 0.9 CoFeB (free) | 1 MgO | 0.5 Fe | 0.5 CoFeB (fixed) | 0.6 Ta

Effects of electronic coupling and electrostatic potential on charge transport in carbon-based molecular electronic junctions

• Richard L. McCreery

Beilstein J. Nanotechnol. 2016, 7, 32–46, doi:10.3762/bjnano.7.4

• absent only when the two planes are orthogonal. Coupling also results in partial charge transfer between the graphene contacts and the molecular layer, which results in a shift in electrostatic potential which affects the observed tunneling barrier. Although the degree of partial charge transfer is

• interactions between the larger G54 graphene fragment and AB, we proposed that the tunneling barrier is related to the offset between the G9–AB HOMO and the G9–AB orbital having significant electron density on the AB molecule [34]. This postulate is consistent both with transport measurements and with

• 1.25 eV for the planar to the orthogonal structures. Our previous postulate that the orbital determining the tunneling barrier is the closest G9–AB orbital with electron density on the AB moiety can now be enhanced by the further postulate that the tunneling orbital span both the entire G9–AB–G9 system

Effects of spin–orbit coupling and many-body correlations in STM transport through copper phthalocyanine

• Benjamin Siegert,
• Andrea Donarini and
• Milena Grifoni

Beilstein J. Nanotechnol. 2015, 6, 2452–2462, doi:10.3762/bjnano.6.254

• molecule is put on a thin insulating layer grown on top of a conducting substrate. The layer functions as a tunneling barrier and decouples the molecule from the substrate. Hence the CuPc molecule acts as a molecular quantum dot weakly coupled by tunneling barriers to metallic leads (here the STM tip and

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

• Henrry M. Osorio,
• Santiago Martín,
• María Carmen López,
• Santiago Marqués-González,
• Simon J. Higgins,
• Richard J. Nichols,
• Paul J. Low and
• Pilar Cea

Beilstein J. Nanotechnol. 2015, 6, 1145–1157, doi:10.3762/bjnano.6.116

• tunneling barrier, which has been taken as 1.64 nm (value obtained from the geometric N…N distance determined with the molecular modeling program Spartan®08 V 1.0.0); φ represents the effective barrier height of the tunneling junction (relative to the Fermi level of Au); α is a fitting parameter related to

Closed-loop conductance scanning tunneling spectroscopy: demonstrating the equivalence to the open-loop alternative

• Chris Hellenthal,
• Kai Sotthewes,
• Martin H. Siekman,
• E. Stefan Kooij and
• Harold J. W. Zandvliet

Beilstein J. Nanotechnol. 2015, 6, 1116–1124, doi:10.3762/bjnano.6.113

• using closed-loop z(V) conductance scanning tunneling spectroscopy (STS) measurements for the determination of the effective tunneling barrier by comparing them to more conventional open-loop I(z) measurements. Through the development of a numerical model, the individual contributions to the effective

• tunneling barrier present in these experiments, such as the work function and the presence of an image charge, are determined quantitatively. This opens up the possibility of determining tunneling barriers of both vacuum and molecular systems in an alternative and more detailed manner. Keywords: image

• charge; scanning tunneling spectroscopy (STS); tunneling barrier; work function; z(V); Introduction Although the scanning tunneling microscope (STM) has been used for the topographical imaging of conductive samples since the early 1980s [1], recent times have seen an increasing interest in the

Electrical contacts to individual SWCNTs: A review

• Wei Liu,
• Christofer Hierold and
• Miroslav Haluska

Beilstein J. Nanotechnol. 2014, 5, 2202–2215, doi:10.3762/bjnano.5.229

• properties. A constant or pulsed current [37][79][80][81] was applied through the electrodes. An instant heating locally in the contact area could remove the adsorbates remaining on the SWCNTs after wet deposition, thus reducing the tunneling barrier for carrier injection at the metal–SWCNT interface

STM study on the self-assembly of oligothiophene-based organic semiconductors

• Elena Mena-Osteritz,
• Marta Urdanpilleta,
• Erwaa El-Hosseiny,
• Berndt Koslowski,
• Paul Ziemann and
• Peter Bäuerle

Beilstein J. Nanotechnol. 2011, 2, 802–808, doi:10.3762/bjnano.2.88

• , center) submolecular resolution was obtained for the oligothiophene backbones. Due to the low negative bias applied and at the limit given by the tunneling barrier of this compound, we can assume that the observed eight lobes per molecule correspond to the local density of states (LDOS) of the molecule

Deconvolution of the density of states of tip and sample through constant-current tunneling spectroscopy

• Holger Pfeifer,
• Berndt Koslowski and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 607–617, doi:10.3762/bjnano.2.64

• -current mode (z–V spectroscopy). The scheme is based on the validity of the Wentzel–Kramers–Brillouin (WKB) approximation and the trapezoidal approximation of the electron potential within the tunneling barrier. In a numerical treatment of z–V spectroscopy, we first analyze how the position and amplitude

• measurement is always obscured by unavoidable interfering influences from other STS constituents such as the tunneling barrier, with its bias-dependent transmission probability, as well as from the LDOS of the probing tip. The problem becomes most clearly visible when referring to the semiclassical Wentzel

• given tunneling barrier, extraction of the sample LDOS is in principle impossible. That used to be the standard situation for previous tunnel junctions with their fixed oxide barriers. In STS, however, at any given sample location, barriers can be experimentally adjusted. In this way, additional

Terthiophene on Au(111): A scanning tunneling microscopy and spectroscopy study

• Berndt Koslowski,
• Anna Tschetschetkin,
• Norbert Maurer,
• Elena Mena-Osteritz,
• Peter Bäuerle and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 561–568, doi:10.3762/bjnano.2.60

• observed linear decrease of the differential tunneling barrier at positive bias when determined on top of a 3T molecule is compared to the bias independent barrier obtained on bare Au(111) surfaces. This striking difference of the barrier behavior with and without adsorbed molecules is interpreted as

• differential barrier height. This not so commonly determined characteristic, describing the voltage dependent tunneling barrier, has been introduced recently in order to remove features of the tunneling tip from STS spectra, assuming the validity of the Wentzel–Kramers–Brillouin (WKB) approximation. Again, 3T

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

• Alexander Weddemann,
• Inga Ennen,
• Anna Regtmeier,
• Camelia Albon,
• Annalena Wolff,
• Katrin Eckstädt,
• Nadine Mill,
• Michael K.-H. Peter,
• Jochen Mattay,
• Carolin Plattner,
• Norbert Sewald and
• Andreas Hütten

Beilstein J. Nanotechnol. 2010, 1, 75–93, doi:10.3762/bjnano.1.10

• et al. showed that chemically synthesized, ligand stabilized nanoparticles can also be used for a bottom-up preparation of granular TMR systems [8][9]. An electrically isolating ligand shell acts as a tunneling barrier. TMR amplitudes of up to 3000% at low temperatures have been reported in such