Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties

• Ionel Stavarache,
• Valentin Adrian Maraloiu,
• Petronela Prepelita and
• Gheorghe Iordache

Beilstein J. Nanotechnol. 2016, 7, 1492–1500, doi:10.3762/bjnano.7.142

• darkness, the current behavior of the Al/n-Si/Ge:SiO2/ITO structure (schematically presented in Figure 5) is determined by the electrons tunneling from the ITO top electrode into the Ge-nps located in the SiO2 oxide layer and the electron transport in Ge:SiO2 film by a tunneling mechanism between

• neighboring Ge-nps [9][37]. The investigated (Ge-nps):SiO2 system behaves like a resistor network where each Ge-np is connected with its neighboring Ge-nps by a finite tunneling resistor. In this way, the activated carriers in the Ge-nps would tunnel to the nearest Ge-nps, following the path with the lowest

• generated in the Ge-nps and in the Si substrate and they move by tunneling between neighboring Ge-nps. During transport, the positively charged holes are dynamically trapped within the Ge-nps incorporated into SiO2 matrix improving the electron injection, leading to an increase of negative photoconductivity

A composite structure based on reduced graphene oxide and metal oxide nanomaterials for chemical sensors

• Vardan Galstyan,
• Elisabetta Comini,
• Iskandar Kholmanov,
• Andrea Ponzoni,
• Veronica Sberveglieri,
• Nicola Poli,
• Guido Faglia and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2016, 7, 1421–1427, doi:10.3762/bjnano.7.133

• potential barrier for electron tunneling acting as a highly conductive electrical path for the transport of electrons through the nanostructure [34]. Therefore, RGO improves the sensing performance of ZnO. Due to this reason, in our future investigations we will study the sensing properties of the composite

Advanced atomic force microscopy techniques III

• Thilo Glatzel and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2016, 7, 1052–1054, doi:10.3762/bjnano.7.98

• microscopy (AFM) celebrates its 30th anniversary this year. It was presented by Binnig, Quate and Gerber in 1986 as an extension of the scanning tunneling microscope (STM) with the possibility to measure forces as small as 10−18 N [1]. Since then many different variations of the force detection method and

Phenalenyl-based mononuclear dysprosium complexes

• Yanhua Lan,
• Andrea Magri,
• Olaf Fuhr and
• Mario Ruben

Beilstein J. Nanotechnol. 2016, 7, 995–1009, doi:10.3762/bjnano.7.92

• relaxation process to be 43.8 K, and the respective pre-exponential factor τ0 to have a value of 3.3 × 10−6 s. Additionally, a saturation of about 5 × 10−4 s, relative to the quantum-tunneling process, is obtained below 5 K. In relaxation processes of SMMs that are to a certain extent subjected to quantum

• effects, the application of a small dc field can remove the state degeneracy, and accordingly also the probability of quantum tunneling. Aiming to explore the relaxation process and to evaluate the quantum tunneling effect, the frequency dependence of the ac susceptibility was estimated at 1.8 K under a

• suppressed quantum tunneling of the magnetization (QTM) [52]. Lastly, ac susceptibilities as a function of the temperature have been measured under a dc field of 200 Oe to estimate the effective relaxation time (Figure 5). The data were fitted with an Arrhenius law function in the temperature range between

A terahertz-vibration to terahertz-radiation converter based on gold nanoobjects: a feasibility study

• Kamil Moldosanov and
• Andrei Postnikov

Beilstein J. Nanotechnol. 2016, 7, 983–989, doi:10.3762/bjnano.7.90

• [17][18], a tunneling of acoustic phonons across nanoscale gaps became an issue of priority. Meanwhile, already in 2010 Beardsley et al. [19] described a working 0.44 THz saser (on the basis of semiconductor superlattices). It seems that metallic nanobars/nanorings supposed to serve as resonators for

• LAVMs, taken in combination with a THz saser (possibly in a different realisation than that of [19]) and interconnected by the phonon tunneling “leaks” between the nanoobjects, may serve as elements of the THz acoustic phononic circuitry. Another idea is that metallic nanobars/nanorings could be used

Noncontact atomic force microscopy III

• Mehmet Z. Baykara and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2016, 7, 946–947, doi:10.3762/bjnano.7.86

• tunneling microscopy (STM) relies on quantum mechanical tunneling of electrons to enable the atomic-resolution imaging of (semi-)conducting sample surfaces, it was the atomic force microscope (AFM) that eventually allowed for nanometer-scale imaging of sample surfaces with no limitations on electrical

The role of morphology and coupling of gold nanoparticles in optical breakdown during picosecond pulse exposures

• Yevgeniy R. Davletshin and
• J. Carl Kumaradas

Beilstein J. Nanotechnol. 2016, 7, 869–880, doi:10.3762/bjnano.7.79

• medium, which models a biological environment, can initiate breakdown (i) through multiphoton absorption and the tunneling effect, usually referred to as laser-induced optical breakdown (LIOB) [26][27]; (ii) through a thermal initiation pathway also known as laser-induced thermal breakdown (LITB) [28][29

• full Keldysh theory for multiphoton ionization [54], the tunneling effect, avalanche ionization, thermal ionization [28][36], diffusion, and recombination losses and photo-thermal emission (PTE) [30] of hot electrons from the gold surface, was solved to determine the dynamics of the free-electron

Thermo-voltage measurements of atomic contacts at low temperature

• Ayelet Ofarim,
• Bastian Kopp,
• Thomas Möller,
• León Martin,
• Johannes Boneberg,
• Paul Leiderer and
• Elke Scheer

Beilstein J. Nanotechnol. 2016, 7, 767–775, doi:10.3762/bjnano.7.68

• ]. Experimental techniques such as scanning tunneling microscopy (STM) and the mechanically controlled break-junction (MCBJ) technique allow investigation of transport properties of atomic-scale devices [18]. Therefore, most approaches for measurements of thermo-voltage, or simultaneous measurements of

• from reduced lifetime, is largely facilitated. Furthermore, temperature-dependent effects of the transmission function that are expected in resonant tunneling situations can be revealed. Thus the ability to measure at variable temperature represents a considerable improvement compared to fixed

Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles

• Julia A. Burunkova,
• Ihor Yu. Denisiuk,
• Dmitri I. Zhuk,
• Lajos Daroczi,
• Attila Csik,
• István Csarnovics and
• Sándor Kokenyesi

Beilstein J. Nanotechnol. 2016, 7, 630–636, doi:10.3762/bjnano.7.55

• , which fill the volume of the composite rather uniformly because of our synthesis technology, and the gold nanoparticles are also attached there, the plasmon field of excited AuNPs can enhance the quantum yield of luminescence. Of course, they should be separated by 5–10 nm, to prevent tunneling of the

Charge and heat transport in soft nanosystems in the presence of time-dependent perturbations

• Alberto Nocera,
• Carmine Antonio Perroni,
• Vincenzo Marigliano Ramaglia and
• Vittorio Cataudella

Beilstein J. Nanotechnol. 2016, 7, 439–464, doi:10.3762/bjnano.7.39

• described above. However, the characteristic frequencies of the external drive are much larger than the electronic tunneling rate. In fact, in these conditions, an effective phase-shift can be produced due to electron–electron interactions, which is intrinsically generated by a non-adiabatic blockade of

• tunneling [40]. However, it has been pointed out that higher frequencies are necessary to observe pumping currents of the same order of magnitude of those observed when a two-parameter pumping mechanism is present [41][42][43][44][45]. Another particularly interesting experiment has been carried out in [46

• frequencies are smaller than the electronic tunneling rates of the device and close to the frequency of the internal vibrational mode. Indeed, in the absence of an internal degree of freedom, it has been theoretically demonstrated that single-parameter charge pumping through a quantum dot in the this regime

Rigid multipodal platforms for metal surfaces

• Michal Valášek,
• Marcin Lindner and
• Marcel Mayor

Beilstein J. Nanotechnol. 2016, 7, 374–405, doi:10.3762/bjnano.7.34

• junctions are based on either electrochemical break junctions [13][14][15] or mechanically controlled break junctions (MCBJ) [7] as well as on scanning tunneling microscopy (STM) [9][16][17]. The ultimate goal of molecular electronics is to use assemblies of molecules or even single molecules as functional

• were characterized by XPS, Fourier transform infrared absorption spectroscopy (FT-IRRAS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and a scanning tunneling microscopy (STM) analysis. As revealed by XPS and NEXAFS analysis, the monolayers derived from the thiol-terminated

• dispersed bright spots (ca. 3–5 nm), fitted to the single or aggregated molecule, placed perpendicularly to the Au(111) surface. This STM-junction operating in the tunneling regime was irradiated with a short excitation pulse to measure the molecular electroluminescence when excited by local electron

Molecular machines operating on the nanoscale: from classical to quantum

• Igor Goychuk

Beilstein J. Nanotechnol. 2016, 7, 328–350, doi:10.3762/bjnano.7.31

• correspond to the states of a proton pump driven by a nonequilibrium electron flow. This is a minimalist toy model for pumps like the cytochrome c oxidase proton pump [1][37]. The driving force is provided by electron energy, Δμ, released by dissipative tunneling of electrons between donor and acceptor

• electron transfer (ET) between two heme metalloclusters seems to be a rate limiting step. Such ET presents vibrationally assisted electron tunneling between two localized quantum states [38][39]. Given the weak electron tunneling coupling between the electronic states, the rate can be calculated using the

• a quantum prefactor, where Vtun is the tunneling coupling, and λ is the reorganization energy of the medium. The energy released in the electron transport is used to pump protons against their electrochemical gradient, Δμp, which corresponds to 2πfL within the previous model. Hence, R = Δμp/|Δμ|. Of

Synthesis and applications of carbon nanomaterials for energy generation and storage

• Marco Notarianni,
• Jinzhang Liu,
• Kristy Vernon and
• Nunzio Motta

Beilstein J. Nanotechnol. 2016, 7, 149–196, doi:10.3762/bjnano.7.17

Single-molecule magnet behavior in 2,2’-bipyrimidine-bridged dilanthanide complexes

• Wen Yu,
• Frank Schramm,
• Eufemio Moreno Pineda,
• Yanhua Lan,
• Olaf Fuhr,
• Jinjie Chen,
• Hironari Isshiki,
• Wolfgang Wernsdorfer,
• Wulf Wulfhekel and
• Mario Ruben

Beilstein J. Nanotechnol. 2016, 7, 126–137, doi:10.3762/bjnano.7.15

• ), 2; Dy(III), 3; Ho(III), 4 and Er(III), 5) has been synthesized and characterized. Sublimation of [Tb(tmhd)3]2bpm onto a Au(111) surface leads to the formation of a homogeneous film with hexagonal pattern, which was studied by scanning tunneling microscopy (STM). The bulk magnetic properties of all

• was measured using AC, DC and micro-SQUID magnetometry techniques. The homo-dinuclear complexes of Dy(III) and Er(III) show single-molecule magnet behavior featuring hysteresis loops. The [Tb(tmhd)3]2bpm was sublimated on Au(111) surfaces and scanning tunneling microscopy results are presented in this

• with a Perkin Elmer Spectrum GX FT-IR system spectrophotometer. Elemental analysis data were collected on an ELEMENTAR Vario Micro Cube. NMR spectra were carried out on a Bruker Ultrashield 500 PLUS spectrometer. Scanning tunneling microscopy. The STM measurements were realized with a homebuilt

Linear and nonlinear optical properties of hybrid metallic–dielectric plasmonic nanoantennas

• Mario Hentschel,
• Bernd Metzger,
• Bastian Knabe,
• Karsten Buse and
• Harald Giessen

Beilstein J. Nanotechnol. 2016, 7, 111–120, doi:10.3762/bjnano.7.13

• fundamentally limits the field strength and what values can actually be achieved. Ultimately, the electric field strength might be limited by either electron tunneling processes between the extremely close spaced metallic nanoparticles [75][76] or by so-called nonlocal effects where the dielectric function of

Charge injection and transport properties of an organic light-emitting diode

• Peter Juhasz,
• Juraj Nevrela,
• Michal Micjan,
• Miroslav Novota,
• Jan Uhrik,
• Lubica Stuchlikova,
• Jan Jakabovic,
• Ladislav Harmatha and
• Martin Weis

Beilstein J. Nanotechnol. 2016, 7, 47–52, doi:10.3762/bjnano.7.5

• ]. However, the 2C-SCLC model is fully valid only if no injection barrier is present at metal–organic semiconductor interface. Previous studies revealed that observed current density–voltage characteristics can be also associated with thermionic emission or Fowler–Nordheim tunneling [14][15][16]. Hence, to

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

• coupling between the molecules and the contacts is demonstrated by the formation of hybrid orbitals in the model structure, which have significant electron density on both the graphene and the molecule. The energies of such hybrid orbitals correlate with tunneling barriers determined experimentally, and

• 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

• “compression” of tunneling barriers predicted to range over 2.4 eV based on the free molecule energy levels to an observed range of 1.3 ± 0.2 eV in carbon-based MJs [31][34]. The current report describes the application of density functional theory (DFT) to carbon-based MJs, in order to investigate which

Chemiresistive/SERS dual sensor based on densely packed gold nanoparticles

• Sanda Boca,
• Cosmin Leordean,
• Simion Astilean and
• Cosmin Farcau

Beilstein J. Nanotechnol. 2015, 6, 2498–2503, doi:10.3762/bjnano.6.259

• share a common principle: nanometric interparticle gaps are needed, for electron tunneling in chemiresistors, and for enhancing electromagnetic fields by plasmon coupling in SERS-based sensors. By exploiting such nano-gaps in self-assembled films of gold nanoparticles, we demonstrate the proof of

• substrate can lead to electrical charge flow through the nanoparticle assembly by applying a voltage on the electrodes. This system can work as a resistive sensor based on the dependence of tunneling currents on the inter-NP tunnel barrier, which can be affected by the molecular species adsorbed on the NPs

• considering that charge transport through the NP assembly occurs mainly by electron tunneling. The tunneling resistance depends exponentially on the interparticle distance l (surface to surface): RT ≈ eβl, where β is a tunneling decay constant that describes the tunneling of electrons along the organic

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

• architectures for power electronic switches and rectifiers [58]. However, the reduction of the Schottky barrier height as well as tunneling processes are still limiting the voltage and efficiency of SiC Schottky barrier diodes. An alternative approach for such devices is the so-called junction barrier Schottky

Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

• Riccardo Frisenda,
• Mickael L. Perrin and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 2477–2484, doi:10.3762/bjnano.6.257

• tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed

• transport [16][17], and inelastic electron tunneling spectroscopy (IETS) [12][13][18][19][20][21], of which the latter is the most popular. Figure 1a schematically depicts the IETS process, where the metallic electrodes are represented as Fermi distributions. In between these electrodes a molecule resides

• in Figure 2a shows the typical signal of an empty junction, in which the conductance after the rupture of the last gold contact decreases exponentially with distance. This is a signature of vacuum tunneling between two metallic electrodes. Once a molecular junction is formed (junction 1, right

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

• splitting of former degenerate levels and a magnetic anisotropy, which can be captured by an effective low-energy spin Hamiltonian. We show that scanning tunneling microscopy-based magnetoconductance measurements can yield clear signatures of both these SOI-induced effects. Keywords: anisotropy; copper

• phthalocyanine; magnetotransport; spin–orbit interaction; scanning tunneling microscopy (STM); Introduction Spin–orbit interaction (SOI) can play a major role in molecular spintronics. For example, in combination with the configuration of the non-magnetic component (organic ligand), it is known to be essential

• enormous anisotropies in both spin and orbital dipole moments [9]. Furthermore, recent experimental findings for cobalt pththalocyanine in a scanning tunneling microscopy (STM) setup [10] suggest that many-body correlations play an important role in the interpretation of the transport measurements. In a

Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

• David Rakhmilevitch and
• Oren Tal

Beilstein J. Nanotechnol. 2015, 6, 2417–2422, doi:10.3762/bjnano.6.249

• before rupture. A typical conductance of approx. 1G0 is measured right before the junction breaks. This conductance value is ascribed to Ag atomic junctions [31][32]. Further elongation leads to an exponential conductance decay, which is the signature of tunneling transport that follows the contact

• tunneling between the Ag electrodes can also be considered as a source for background conduction [35]. We speculate that the different response of the background and the Kondo conductance to junction elongation (Figure 2c,d) comes from the different response of the orbital hybridization at the metal

Sub-monolayer film growth of a volatile lanthanide complex on metallic surfaces

• Hironari Isshiki,
• Jinjie Chen,
• Kevin Edelmann and
• Wulf Wulfhekel

Beilstein J. Nanotechnol. 2015, 6, 2412–2416, doi:10.3762/bjnano.6.248

• , Germany 10.3762/bjnano.6.248 Abstract We deposited a volatile lanthanide complex, tris(2,2,6,6-tetramethyl-3,5-heptanedionato)terbium(III), onto metal surfaces of Cu(111), Ag(111) and Au(111) in vacuum and observed well-ordered sub-monolayer films with low temperature (5 K) scanning tunneling microscopy

• . The films show a distorted three-fold symmetry with a commensurate structure. Scanning tunneling spectroscopy reveals molecular orbitals delocalized on the ligands of the molecule. Our results imply that this complex can be transferred onto the metal substrates without molecular decomposition or

• contamination of the surface. This new rare-earth-based class of molecules broadens the choice of molecular magnets to study with scanning tunneling microscopy. Keywords: β-diketonate; molecular films; scanning tunneling microscopy; terbium; volatile lanthanide complex; Introduction Several carefully designed

Core-level spectra and molecular deformation in adsorption: V-shaped pentacene on Al(001)

• Anu Baby,
• He Lin,
• Gian Paolo Brivio,
• Luca Floreano and
• Guido Fratesi

Beilstein J. Nanotechnol. 2015, 6, 2242–2251, doi:10.3762/bjnano.6.230

• higher adsorption energies (at least by 0.7 eV) and hence are considered unphysical. Scanning tunneling microscopy (STM) measurements showed that a large percentage of pentacene molecules adsorb with a V-shape on a reconstructed Al(001) surface with the longer axis along the [110] direction. The

Thermoelectricity in molecular junctions with harmonic and anharmonic modes

• Bijay Kumar Agarwalla,
• Jian-Hua Jiang and
• Dvira Segal

Beilstein J. Nanotechnol. 2015, 6, 2129–2139, doi:10.3762/bjnano.6.218

• , the model allows for simulations of transport characteristics in conjugated molecular junctions with delocalized electrons. In this work, we focus on a different class of molecular junctions as depicted in Figure 1. In such systems, two electronic levels are coupled via a weak tunneling element, but

• nondiagonal (or nonlocal) as well as diagonal (local) electron–vibration interactions [15]. Here, in contrast, we simplify the junction model and omit the contribution of direct tunneling between the D and A units. This simplification allows us to derive a closed (perturbative) expression for the cumulant

• (infinite) of diagrams (ring type) in the perturbative series, taking into account all electron scattering processes that are facilitated by the absorption or emission of a single quantum ω0. Physically, this summation collects not only sequential tunneling electrons, but all coordinated multi-tunneling