Charged particle single nanometre manufacturing

• Philip D. Prewett,
• Cornelis W. Hagen,
• Claudia Lenk,
• Steve Lenk,
• Marcus Kaestner,
• Tzvetan Ivanov,
• Ahmad Ahmad,
• Ivo W. Rangelow,
• Xiaoqing Shi,
• Stuart A. Boden,
• Alex P. G. Robinson,
• Dongxu Yang,
• Sangeetha Hari,
• Marijke Scotuzzi and
• Ejaz Huq

Beilstein J. Nanotechnol. 2018, 9, 2855–2882, doi:10.3762/bjnano.9.266

• lithography, FE-eSPL. This has been developed out of scanning tunneling microscopy using lower-energy electrons (tens of electronvolts rather than the tens of kiloelectronvolts of the other techniques). It has the considerable advantage of being employed without the need for a vacuum system, in ambient air

• , the second approach, also stems from microscopy in the form of scanning tunneling microscopy and atomic force microscopy; the corresponding lithography techniques include scanning tunneling lithography and field-emission scanning probe lithography. The electron microscope evolved from the use of

• capable of writing with 8 nm feature resolution over a 200 mm wafer substrate [8]. The state of the art for lithography using scanning proximity probes is the Zyvector system from Zyvex Labs [9]. It provides atomic resolution – the removal of a single atom – using scanning tunneling lithography, but the

Variation of the photoluminescence spectrum of InAs/GaAs heterostructures grown by ion-beam deposition

• Alexander S. Pashchenko,
• Leonid S. Lunin,
• Eleonora M. Danilina and
• Sergei N. Chebotarev

Beilstein J. Nanotechnol. 2018, 9, 2794–2801, doi:10.3762/bjnano.9.261

• -GaAs layer thickness, on the one hand, limits the fluctuation of QD heights in vertically stacked arrays and stabilizes them and, on the other hand, improves the charge transfer due to the resonant tunneling between the vertical InAs QD layers. Photoluminescence properties of InAs/GaAsBi

Low cost tips for tip-enhanced Raman spectroscopy fabricated by two-step electrochemical etching of 125 µm diameter gold wires

• Antonino Foti,
• Francesco Barreca,
• Enza Fazio,
• Cristiano D’Andrea,
• Paolo Matteini,
• Onofrio Maria Maragò and
• Pietro Giuseppe Gucciardi

Beilstein J. Nanotechnol. 2018, 9, 2718–2729, doi:10.3762/bjnano.9.254

• ]. The tips efficiently enhance and confine the electromagnetic field at the nanoscale [8][9] or even at sub-nanometer levels [10]. TERS has a sensitivity that can reach the single molecule level [11][12]. TERS setups based on atomic force microscopy (AFM) [1][13], scanning tunneling microscopy (STM) [14

• if excited at energies below the sp/d interband transition. Enhanced inelastic electron tunneling through the gap seems to be the origin of photon emission [52][55], leading to electronic Raman scattering (ERS) of the laser photons [53] which is at the origin of the background observed in TERS and

Two-dimensional semiconductors pave the way towards dopant-based quantum computing

• José Carlos Abadillo-Uriel,
• Belita Koiller and
• María José Calderón

Beilstein J. Nanotechnol. 2018, 9, 2668–2673, doi:10.3762/bjnano.9.249

• unsolved, namely the control over exchange interactions and tunneling between two donors, which presents a peculiar oscillatory behavior as the dopants relative positions vary at the scale of the lattice parameter. Such behavior is due to the valley degeneracy in the conduction band of silicon, and does

High-temperature magnetism and microstructure of a semiconducting ferromagnetic (GaSb)_1−x(MnSb)_x alloy

• Leonid N. Oveshnikov,
• Elena I. Nekhaeva,
• Alexey V. Kochura,
• Alexander B. Davydov,
• Mikhail A. Shakhov,
• Sergey F. Marenkin,
• Oleg A. Novodvorskii,
• Alexander P. Kuzmenko,
• Alexander L. Vasiliev,
• Boris A. Aronzon and
• Erkki Lahderanta

Beilstein J. Nanotechnol. 2018, 9, 2457–2465, doi:10.3762/bjnano.9.230

• interaction is affected by the appearance of Schottky barriers at the MnSb/GaSb boundaries. Basically, these type of barriers appear on the semiconductor/metal interfaces providing a tunneling charge transfer across the boundary, if the barrier is high enough. In the present case, Schottky barriers may appear

• the same nature. At 50 K we observe a local minimum in both curves. The increase above 50 K can be related to the presence of Schottky barriers. If both AHE and nMR correspond to the interaction with MnSb inclusions, then their amplitudes are defined by the tunneling intensity, which increases with

Directional light beams by design from electrically driven elliptical slit antennas

• Shuiyan Cao,
• Eric Le Moal,
• Quanbo Jiang,
• Aurélien Drezet,
• Serge Huant,
• Jean-Paul Hugonin,
• Gérald Dujardin and
• Elizabeth Boer-Duchemin

Beilstein J. Nanotechnol. 2018, 9, 2361–2371, doi:10.3762/bjnano.9.221

• is located at one focus of the ellipse. In this study, SPPs are generated through inelastic electron tunneling between a gold surface and the tip of a scanning tunneling microscope. Keywords: elliptical antenna; inelastic electron tunneling; optical antenna; plasmonics; scanning tunneling microscopy

• nanosource can be a nanoscale tunnel junction where the emission process relies on inelastic electron tunneling effects [20]. A central issue for miniaturized electrical light sources is the control of their emission direction, especially given that SPP excitation with electrons results in a broad power

• spread of the emitted beam is inversely proportional to the length of the ellipse axes. Results and Discussion Figure 1 shows schematics of the experiment performed in this study. All experiments are carried out in air and at room temperature using a scanning tunneling microscope (STM) head mounted on

Spin-coated planar Sb₂S₃ hybrid solar cells approaching 5% efficiency

• Pascal Kaienburg,
• Benjamin Klingebiel and
• Thomas Kirchartz

Beilstein J. Nanotechnol. 2018, 9, 2114–2124, doi:10.3762/bjnano.9.200

• ] since charges are quickly extracted from the absorber. However, the benefits are restricted by recombination via trap-assisted tunneling [24] which must be compensated by increasing the absorber thickness for optimized performance. A major challenge in the processing of ETA solar cells is the improper

• MoOx forms a tunneling junction with the HTM is typical for organic solar cells in an n-i-p configuration. The cell area was 0.16 cm2. Layer and device characterization: The scanning electron microscope was a Zeiss (Leo) Gemini 1550 with Shottky field-emission cathode and an in-lens detector. The

A variable probe pitch micro-Hall effect method

• Maria-Louise Witthøft,
• Frederik W. Østerberg,
• Janusz Bogdanowicz,
• Rong Lin,
• Henrik H. Henrichsen,
• Ole Hansen and
• Dirch H. Petersen

Beilstein J. Nanotechnol. 2018, 9, 2032–2039, doi:10.3762/bjnano.9.192

• four electrodes has been developed [11][12]. Similar strategies using variable probe pitch multi-point probes have been used for other systems, including current-in-plane tunneling measurements [13], junction-leakage measurements [14] and surface-conductivity measurements of bulk materials [15][16]. In

Metal-free catalysis based on nitrogen-doped carbon nanomaterials: a photoelectron spectroscopy point of view

• Mattia Scardamaglia and
• Carla Bittencourt

Beilstein J. Nanotechnol. 2018, 9, 2015–2031, doi:10.3762/bjnano.9.191

• the electronic states of graphene. In general, point defects generate localized states at the Fermi level, easily identifiable as protrusion by scanning tunneling microscopy (STM) [56], while carbon vacancies are responsible for an opening of the energy gap [57]. The increase in the density of states

Recent highlights in nanoscale and mesoscale friction

• Andrea Vanossi,
• Dirk Dietzel,
• Andre Schirmeisen,
• Ernst Meyer,
• Rémy Pawlak,
• Thilo Glatzel,
• Marcin Kisiel,
• Shigeki Kawai and
• Nicola Manini

Beilstein J. Nanotechnol. 2018, 9, 1995–2014, doi:10.3762/bjnano.9.190

• by the action of a probing tip along a track of 100 nm on a Au(111) surface (Figure 8). The method to move the molecules is based on inelastic tunneling through which the electrons induce molecular vibrations, which then lead to increased diffusion. Depending on the polarity of the applied bias

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

• for producing these functional units based upon the electromigration of metal constrictions. Results: We combine multiple nanofabrication steps to realize in-plane tunneling junctions made of two gold electrodes, separated by a sub-nanometer gap acting as the feedgap of an optical antenna. We

• electrically characterize the transport properties of the junctions in the light of the Fowler–Nordheim representation and the Simmons model for electron tunneling. We demonstrate light emission from the feedgap upon electron injection and show examples of how this nanoscale light source can be coupled to

• waveguiding structures. Conclusion: Electromigrated in-plane tunneling optical antennas feature interesting properties with their unique functionality enabling interfacing electrons and photons at the atomic scale and with the same device. This technology may open new routes for device-to-device communication

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

• Hichem Ferhati Faycal Djeffal Toufik Bentrcia LEA, Department of Electronics, University Mostefa Benboulaid-Batna 2, Batna 05000, Algeria LEPCM, University of Batna 1, Batna 05000, Algeria 10.3762/bjnano.9.177 Abstract In this paper, a new nanoscale double-gate junctionless tunneling field-effect

• , where the optimized design exhibits an improved switching behavior at the nanoscale level. These results make the optimized device suitable for designing digital circuit for high-performance nanoelectronic applications. Keywords: ambipolar conduction; heterojunctions; junctionless tunneling field

• transistors (MOSFETs) and their complements in nanoelectronic circuit designs [1][2][3][4]. In this context, small swing-switch devices such as double-gate tunneling field-effect transistors (DG TFETs) are gaining attention because of their good subthreshold characteristics, high scalability and low OFF

Tunable fractional Fourier transform implementation of electronic wave functions in atomically thin materials

• Daniela Dragoman

Beilstein J. Nanotechnol. 2018, 9, 1828–1833, doi:10.3762/bjnano.9.174

• function does not need to be of plane-wave type, i.e., it can also be spatially divergent or convergent. In particular, divergent wave functions, as in [17], can be produced by localized electron sources/sharp tunneling conductive tips. In general, the shape of the transverse wave function can be tuned via

A zero-dimensional topologically nontrivial state in a superconducting quantum dot

• Pasquale Marra,
• Alessandro Braggio and
• Roberta Citro

Beilstein J. Nanotechnol. 2018, 9, 1705–1714, doi:10.3762/bjnano.9.162

• electron dispersion in the two superconducting leads. In the following we furthermore assume that the bare electron dispersion varies in the interval [−D,D] and that the density of states is ρ0 = 1/(2D) with 2D the total bandwidth. The tunneling between the dot and the leads is described by the tunnel

• Hamiltonians, which read where t = tL = tR is the transparency of the dot–lead tunneling. We assume that the junction is symmetric and that the tunneling amplitudes do not depend on the electron momenta (wide band limit approximation). In the limit of a large superconducting gap, i.e., when the gap is larger

• in a magnetic field B and electric gate ε coupled with two superconducting leads. The two energy levels are respectively ε ± B. The dot is coupled to the superconducting leads via tunneling junctions with transparency t. The Josephson current Iφ through the dot depends on the gauge-invariant phase

Toward the use of CVD-grown MoS₂ nanosheets as field-emission source

• Geetanjali Deokar,
• Nitul S. Rajput,
• Junjie Li,
• Francis Leonard Deepak,
• Wei Ou-Yang,
• Nicolas Reckinger,
• Carla Bittencourt,
• Jean-Francois Colomer and
• Mustapha Jouiad

Beilstein J. Nanotechnol. 2018, 9, 1686–1694, doi:10.3762/bjnano.9.160

• on the FTO sample is displayed. The ln(J/E2) versus 1/E graph of the emission data is shown in the inset of Figure 6a. The linear behavior indicates that FE from the NSs is dominated by the tunneling effect. It can be seen that the density of emission current increases rapidly along with the

• cathode greatly influences the field-emission performance and the electrons are easier to be extracted from a film with more exposed edges [32]. Hence, we believe that the tip-like geometry (Figure 1d) and exposed edges (Figure 4) of the MoS2 NSs are enhancing the tunneling probability for electrons in

Josephson effect in junctions of conventional and topological superconductors

• Alex Zazunov,
• Albert Iks,
• Miguel Alvarado,
• Alfredo Levy Yeyati and
• Reinhold Egger

Beilstein J. Nanotechnol. 2018, 9, 1659–1676, doi:10.3762/bjnano.9.158

• ] then rule out a supercurrent for TS wires in the deep topological regime. We show below that unless B is inadvertently aligned with the MBS spin polarization axis, spin mixing will indeed generate a supercurrent. The S/TS leads are coupled to the QD via a tunneling Hamiltonian [70], where ψσ and ψ are

• and take real-valued tunnel amplitudes λS/TS, see Figure 1a, using a gauge where the superconducting phase difference appears via the QD–TS tunneling term. These tunnel amplitudes contain density-of-states factors for the respective leads. The operator expression for the current flowing through the

• that they include density-of-state factors again. The parameter t0 (with 0 ≤ t0 ≤ 1) determines the transparency of the SAC in the normal-conducting state [36], cf. Equation 36, Note that in Equation 41 we have again assumed spin-conserving tunneling, where only spin-↑ fermions in the SAC are tunnel

Solid-state Stern–Gerlach spin splitter for magnetic field sensing, spintronics, and quantum computing

• Kristofer Björnson and
• Annica M. Black-Schaffer

Beilstein J. Nanotechnol. 2018, 9, 1558–1563, doi:10.3762/bjnano.9.147

• the transfer processes between the leads and the circular edge. We will here assume that this process preserves phase coherence between the states in the leads and the TI edge states, and that it is described by a single tunneling parameter t, which we for now set to t = 1 to indicate perfect

• proportional to the identity matrix and therefore only contribute to the irrelevant α phase. Discussion We would like to end with a few comments on some of the assumptions made when deriving the above results. First of all, the tunneling parameter t, which otherwise would have multiplied the L and R matrices

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

• of this amplitude equality by analyzing the spatial Rabi oscillations of the quantum states of a quantum dot that is tunneling-coupled to the Majorana bound states. Results: We find two resonant Rabi driving energies that correspond to the energy splitting due to the coupling of two spatially

• Majorana bound states that have an exponentially protected small splitting energy. As shown in Figure 1a, one of the Majorana bound states is coupled to the quantum dot with a single electron tunneling through a potential barrier. The barrier is produced by a voltage gate, which is implemented between the

• quantum dot and the Majorana island. If an ac voltage is applied to the gate, the tunneling strength between the quantum dot and the Majorana bound states will be driven periodically [39]. We show that there are two resonant driving energies that induce coherent spatial Rabi oscillations between the

Robust topological phase in proximitized core–shell nanowires coupled to multiple superconductors

• Tudor D. Stanescu,
• Anna Sitek and
• Andrei Manolescu

Beilstein J. Nanotechnol. 2018, 9, 1512–1526, doi:10.3762/bjnano.9.142

• produced in a charge transport measurement by tunneling electrons between the semiconductor wire and external electrodes attached to its ends [14][15][16][17][18][19][20][21][22][23][24]. These experiments have provided strong indications regarding the presence of Majorana bound states at the end of the

Electronic conduction during the formation stages of a single-molecule junction

• Atindra Nath Pal,
• Tal Klein,
• Ayelet Vilan and
• Oren Tal

Beilstein J. Nanotechnol. 2018, 9, 1471–1477, doi:10.3762/bjnano.9.138

• scenarios in which a single-molecule junction is formed. Future control over such processes may pave the way for directed formation of preferred junction structures. Keywords: break junction; electron–vibration interactions; electronic transport; inelastic electron tunneling spectroscopy; molecular

• the tunneling transport regime. When vanadocene molecules are introduced, additional conductance plateaus appear below 1 G0, indicating the formation of a metal–molecule–metal junction after the Ag contact is broken. Interestingly, the introduction of molecules into the metal junction also yields new

• histograms taken before and after the introduction of vanadocene molecules. The histogram for bare Ag junctions (blue) shows a conductance peak at ≈1 G0, which is related to single-atom junctions, and a tail at low conductance due to electron tunneling after the junctions are broken. The introduction of

Robust midgap states in band-inverted junctions under electric and magnetic fields

• Álvaro Díaz-Fernández,
• Natalia del Valle and
• Francisco Domínguez-Adame

Beilstein J. Nanotechnol. 2018, 9, 1405–1413, doi:10.3762/bjnano.9.133

• crystalline insulator states in Pb1−xSnxSe [9]. High-resolution scanning tunneling microscopy studies of these topological crystalline insulators provided strong evidence of the coexistence of massless Dirac fermions, protected by crystal symmetry, with massive Dirac fermions consistent with crystal-symmetry

Interplay between pairing and correlations in spin-polarized bound states

• Szczepan Głodzik,
• Aksel Kobiałka,
• Anna Gorczyca-Goraj,
• Andrzej Ptok,
• Grzegorz Górski,
• Maciej M. Maśka and
• Tadeusz Domański

Beilstein J. Nanotechnol. 2018, 9, 1370–1380, doi:10.3762/bjnano.9.129

• ][13][14]. In-gap states (appearing in pairs symmetrically around the Fermi level) can be nowadays controlled electrostatically or magnetically [12] whereas their topography, spatial extent and polarization can be precisely inspected by the state-of-art tunneling measurements [15][16]. It has been

• the Kondo and the leaking Majorana quasiparticle can be confronted with each other. These magnetically polarized YSR and Majorana quasiparticles as well as the subgap Kondo effect can be experimentally verified using tunneling heterostructures with ferromagnetic lead (STM tip). Results and Discussion

• sufficiently long wire (εm = 0) the Kondo effect persists only in the spin-channel ↓, whereas for ↑ electrons there appears a dip in the spectral density at ω = 0. The resulting tunneling conductance is then partly reduced (from the perfect value 2e2/h) to the fractional value 3e2/2h [67][68][71][72][73]. In

Disorder-induced suppression of the zero-bias conductance peak splitting in topological superconducting nanowires

• Jun-Tong Ren,
• Hai-Feng Lü,
• Sha-Sha Ke,
• Yong Guo and
• Huai-Wu Zhang

Beilstein J. Nanotechnol. 2018, 9, 1358–1369, doi:10.3762/bjnano.9.128

• Majorana zero mode, the noise Fano factor approaches zero in the low bias voltage limit due to the resonant Andreev tunneling. However, the Fano factor is finite in the case of a disorder-induced zero-bias peak. Keywords: conductance peak spacing; disorder; Majorana energy splitting; shot noise; zero-bias

• several experiments since 2012 [23][24][25][26][27][28][29][30]. As an important signature of MBSs in the semiconductor nanowires which are proximity-coupled to s-wave superconductors, the zero-bias conductance peak has been observed in the tunneling spectra in the presence of a finite magnetic field [23

• work, three different types of intrinsic disorder in the nanowire are considered: the fluctuations of the site-dependent chemical potential, the nonlinear tunneling between neighboring sites, and the disorder arising in the pairing as a result of inhomogeneous superconductor–semiconductor coupling. In

Andreev spectrum and supercurrents in nanowire-based SNS junctions containing Majorana bound states

• Jorge Cayao,
• Annica M. Black-Schaffer,
• Elsa Prada and
• Ramón Aguado

Beilstein J. Nanotechnol. 2018, 9, 1339–1357, doi:10.3762/bjnano.9.127

• , fault-tolerant quantum computation [4][5][6]. Tunneling into such zero-energy MBSs results in a zero-bias peak of high 2e2/h in the tunnelling conductance in normal–superconductor (NS) junctions due to perfect Andreev reflection into a particle–hole symmetric state [7]. Early tunnelling experiments in

• similar to the effect of temperature discussed above. Notice that in the tunnel regime, τ = 0.6, I() is approximately zero. For the sawtooth profile at = π is preserved and robust when τ is reduced from the fully transparent to the tunnel regime, as seen in Figure 15b. Quite remarkably, in the tunneling

• transmission, i.e., it is preserved even in the tunneling regime. And finally, we showed that reasonable fluctuations in the chemical potential μ (up to 5μ) do not affect the sawtooth profile of I() at = π. Our main contribution are summarized as follows. In short and long SNS junctions of finite length four

Proximity effect in a two-dimensional electron gas coupled to a thin superconducting layer

• Christopher Reeg,
• Daniel Loss and
• Jelena Klinovaja

Beilstein J. Nanotechnol. 2018, 9, 1263–1271, doi:10.3762/bjnano.9.118

• -energy, we find that the induced gap in the presence of only Rashba spin–orbit coupling can be made comparable to the bulk gap of the superconductor only if the tunneling energy scale exceeds the large level spacing of the superconducting layer. As in the 1D case, the large tunneling energy scale induces

• , μs, and Δ the effective mass, chemical potential, and pairing potential of the superconductor, respectively. Local tunneling at the interface between the two materials is assumed to conserve both spin and momentum, where t is the tunneling amplitude. We must take the 2DEG to be located at some finite

• z2D (0 < z2D < d) due to the breakdown of the tunneling Hamiltonian approach for the case where the 2DEG is located at the boundary of the superconductor. The breakdown of the tunneling Hamiltonian results from our neglect of the thickness of the 2DEG (for related calculations in which the finite