Computing the T-matrix of a scattering object with multiple plane wave illuminations

• Martin Fruhnert,
• Ivan Fernandez-Corbaton,
• Vassilios Yannopapas and
• Carsten Rockstuhl

Beilstein J. Nanotechnol. 2017, 8, 614–626, doi:10.3762/bjnano.8.66

• , which is characterized by the permittivity ε(ω) and the permeability μ(ω). The complex expansion coefficients anm(ω) and bnm(ω) are called scattering coefficients and the coefficients pnm(ω) and qnm(ω) are called incident coefficients. Together they contain all relevant information about the interaction

• are zero. Let us consider a single dielectric sphere with a radius of 100 nm and a relative permittivity of 16 in vacuum. The Mie-coefficients of this sphere for the first two orders are non-negligible at 600 THz. Such a high-permittivity sphere is nowadays at the focus of interest since it sustains a

• experimental data for the dispersive permittivity of silver [43]. Such objects can be fabricated in large quantities by self assembly methods, e.g., by connecting commercially available metal nanospheres with a linker molecule [44]. We set N = 2, because the higher orders do not contribute notably. For general

Advances in the fabrication of graphene transistors on flexible substrates

• Gabriele Fisichella,
• Stella Lo Verso,
• Silvestra Di Marco,
• Vincenzo Vinciguerra,
• Emanuela Schilirò,
• Salvatore Di Franco,
• Raffaella Lo Nigro,
• Fabrizio Roccaforte,
• Amaia Zurutuza,
• Alba Centeno,
• Sebastiano Ravesi and
• Filippo Giannazzo

Beilstein J. Nanotechnol. 2017, 8, 467–474, doi:10.3762/bjnano.8.50

• relevant for the fabrication of a FET where the properties of the gate dielectric (e.g., permittivity, leakage current, critical breakdown field) are crucial for the device operation. Results and Discussion Low temperature gate dielectric In our experiments we developed a 100 °C PE-ALD process using a PE

Impact of contact resistance on the electrical properties of MoS₂ transistors at practical operating temperatures

• Filippo Giannazzo,
• Gabriele Fisichella,
• Aurora Piazza,
• Salvatore Di Franco,
• Giuseppe Greco,
• Simonpietro Agnello and
• Fabrizio Roccaforte

Beilstein J. Nanotechnol. 2017, 8, 254–263, doi:10.3762/bjnano.8.28

• ≈ 9.1 × 10−5 F/m2 (ε0 is the vacuum dielectric constant, εox = 3.9, tox = 380 nm, the permittivity and the thickness of the SiO2 film, respectively), on the capacitance of the MoS2 depletion region, Cs, as well as on the capacitance associated with MoS2/SiO2 interface traps, Cit [5]. In the depletion

Tunable plasmons in regular planar arrays of graphene nanoribbons with armchair and zigzag-shaped edges

• Cristian Vacacela Gomez,
• Michele Pisarra,
• Mario Gravina and
• Antonello Sindona

Beilstein J. Nanotechnol. 2017, 8, 172–182, doi:10.3762/bjnano.8.18

• correction in mind, we can introduce the inverse dielectric matrix: The zeros in the real part of the macroscopic dielectric function (permittivity) provide the condition for a plasmon resonance to occur, stated as: The imaginary part of the inverse permittivity is proportional to so-called energy loss (EL

• real permittivity, satisfying the condition given by Equation 7. It has been further demonstrated that extrinsic 4ZGNR presents only an intraband plasmon structure, independently on the positive doping level used (below ca. 1 eV), while both intraband and interband plasmons coexist in 5AGNR [31]. To

• in energy, with the zeroes of the real permittivity being hidden by the Landau damping mechanism, associated to single-particle excitation processes [25][46][47][48]. In 11AGNR the same modes strongly interfere and largely dominate with respect to single-particle excitations. A similar interplay was

Morphology of SiO₂ films as a key factor in alignment of liquid crystals with negative dielectric anisotropy

• Volodymyr Tkachenko,
• Antigone Marino,
• Eva Otón,
• Noureddine Bennis and
• Josè Manuel Otón

Beilstein J. Nanotechnol. 2016, 7, 1743–1748, doi:10.3762/bjnano.7.167

• system, whose coordinates (x',y',z') are chosen with the y' axis normal to the incidence plane, and the z' axis normal to the sample plane. The second one is the sample reference system, whose coordinates (x,y,z) diagonalize the anisotropic permittivity tensor. These two systems are related to each other

• dielectric function εj of porous SiO2 layers was described using the effective media theory of Bruggeman [24], generalized for ellipsoidal inclusions of two components which are equally oriented and randomly dispersed [25]: Here p is the porosity (volume fraction of pore), ε1 = 1 is the permittivity of air

• , and ε2 is the permittivity of SiO2 [26]. Lj are the adjustable depolarization factors for the three main axes of the ellipsoidal inclusions, describing the effect of inclusion shape on the anisotropic dielectric function. The depolarization factor dependence on light polarization is easy to

Fingerprints of a size-dependent crossover in the dimensionality of electronic conduction in Au-seeded Ge nanowires

• Maria Koleśnik-Gray,
• Gillian Collins,
• Justin D. Holmes and
• Vojislav Krstić

Beilstein J. Nanotechnol. 2016, 7, 1574–1578, doi:10.3762/bjnano.7.151

• (screening) length, , which is defined as [27]: where εNW = 16 is the dielectric constant of the NW material (assumed the same as for bulk Ge [28]), ε0 the vacuum permittivity, kB the Boltzmann constant, T the temperature and q the electron charge. In Figure 4, is plotted together with R as a function of Nd

Localized surface plasmons in structures with linear Au nanoantennas on a SiO₂/Si surface

• Ilya A. Milekhin,
• Sergei A. Kuznetsov,
• Ekaterina E. Rodyakina,
• Alexander G. Milekhin,
• Alexander V. Latyshev and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2016, 7, 1519–1526, doi:10.3762/bjnano.7.145

• thickness less than or equal to 100 nm formed on a silicon substrate. The dielectric functions of SiO2 and Si used in the simulations were taken from [37]. Gold was modeled as a lossy dispersive medium with the dielectric permittivity εAu described by the classical Drude formula: where ν is the radiation

Diameter-driven crossover in resistive behaviour of heavily doped self-seeded germanium nanowires

• Stephen Connaughton,
• Maria Koleśnik-Gray,
• Richard Hobbs,
• Olan Lotty,
• Justin D. Holmes and
• Vojislav Krstić

Beilstein J. Nanotechnol. 2016, 7, 1284–1288, doi:10.3762/bjnano.7.119

• coordinates [20][21] and for simplicity assuming a constant free-hole concentration nh. One finds the expression [22] where Φ0 is the electrostatic potential at the core/shell interface, ε0 is the vacuum permittivity, εr the dielectric constant of germanium, and e the elementary charge. The confinement of

Tunable longitudinal modes in extended silver nanoparticle assemblies

• Serene S. Bayram,
• Klas Lindfors and
• Amy Szuchmacher Blum

Beilstein J. Nanotechnol. 2016, 7, 1219–1228, doi:10.3762/bjnano.7.113

• simulations. The particle aggregates obtained in this way well resemble the structures in the experiments (Figure 2). Each silver particle was represented by a single dipole with a polarizability given by the expression 4πε2r3[ε1(ω) − ε2]/[ε1(ω) + 2ε2], where ε2 is the permittivity of the medium surrounding

• the particle, ε1(ω) is the frequency-dependent permittivity of silver, and r is the particle radius. This expression for the polarizability follows from the quasi-static approximation and is accurate for particles much smaller than the wavelength [43]. For silver published values for the permittivity

Photocurrent generation in carbon nanotube/cubic-phase HfO₂ nanoparticle hybrid nanocomposites

• Protima Rauwel,
• Augustinas Galeckas,
• Martin Salumaa,
• Frédérique Ducroquet and
• Erwan Rauwel

Beilstein J. Nanotechnol. 2016, 7, 1075–1085, doi:10.3762/bjnano.7.101

• its more interesting properties such as higher dielectric permittivity via doping [17] and substrate-induced strain. Many systems and processes were developed to reach this goal. One advantage of studying this material for other properties is that the microelectronic industry already produces and

Dielectrophoresis of gold nanoparticles conjugated to DNA origami structures

• Anja Henning-Knechtel,
• Matthew Wiens,
• Mathias Lakatos,
• Andreas Heerwig,
• Frieder Ostermaier,
• Nora Haufe and
• Michael Mertig

Beilstein J. Nanotechnol. 2016, 7, 948–956, doi:10.3762/bjnano.7.87

• electrically contacted outside the liquid volume with tungsten needles that are connected to a frequency and voltage synthesizer. DEP is influenced by the complex permittivity of the manipulating object () and its surrounding medium (). This parameter is at low and high frequencies a function of the electrical

Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Gianluigi Zito,
• Teresa Cacace,
• Antigone Marino,
• José M. Otón and
• Morten A. Geday

Beilstein J. Nanotechnol. 2016, 7, 825–833, doi:10.3762/bjnano.7.74

• in thin cells is dictated by the anchoring forces of the conditioned surfaces. However, the orientation may be altered if an external (electric) field above a certain threshold voltage (Vth) is applied. As a result, the effective permittivity of the LC material varies with the applied voltage. The LC

• electric field (Figure 7a) because the LC molecules do not change their position, and there is not any change of their effective dielectric permittivity. The SWCNT-doped LC cell impedance is variable according to Figure 7b. In an initial unbiased state (0 V), the electrical behavior is close to that of a

Characterisation of thin films of graphene–surfactant composites produced through a novel semi-automated method

• Nik J. Walch,
• Alexei Nabok,
• Frank Davis and
• Séamus P. J. Higson

Beilstein J. Nanotechnol. 2016, 7, 209–219, doi:10.3762/bjnano.7.19

• . A. Woollam data analysis software, which is given below as a dispersion function of a complex dielectric permittivity, ε(hν): where ε1∞ is the dielectric permittivity at infinite frequency, Ek, Ak and Bk are, respectively, the position, amplitude, and half-width of the k-th Lorentzian peak. There

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

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

• cross-linked nanoparticle films [6][14]. The effective permittivity in the environment of the nanoparticles can increase due to the adsorption of analytes, which can replace ligands or fill up inter-molecular voids on the surface of the nanoparticles. This can decrease the activation energy for electron

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

• build in potential (Vb) and the width of the SCR (W): where x corresponds to the distance from the p/n-junction. The total width of such an abrupt SCR is given by: where N is ND or NA depending on whether NA >> ND or vice versa and ε = 9.66 is the relative permittivity of SiC. For the case discussed

Electroviscous effect on fluid drag in a microchannel with large zeta potential

• Dalei Jing and
• Bharat Bhushan

Beilstein J. Nanotechnol. 2015, 6, 2207–2216, doi:10.3762/bjnano.6.226

• is the characteristic thickness of EDL, and is given by [5], where ε is the dielectric constant of the electrolyte, ε0 is the vacuum permittivity, kB is the Boltzmann constant, T is the absolute temperature, n0 is the bulk ionic concentration of the symmetric electrolyte, z is the valence of the ions

Radiation losses in the microwave K_u band in magneto-electric nanocomposites

• Talwinder Kaur,
• Sachin Kumar,
• Jyoti Sharma and
• A. K. Srivastava

Beilstein J. Nanotechnol. 2015, 6, 1700–1707, doi:10.3762/bjnano.6.173

• energy. Reflection loss calculation has been carried out by using the input impedance from the following relations in accordance with theory of absorbing wall [41]: where Z is the normalized input impedance, ε* is complex permittivity and µ* is the complex permeability, λ is the wavelength and tis the

• thickness of the sample pellet. It has been observed from XRD and VNA analysis that reflection loss depends on size of the crystallite size. Permittivity and permeability are calculated according to Nicholson–Ross–Weir method. Figure 7 is showing the real (µ′) and the imaginary part (µ″) of the complex

• permeability and Figure 8 illustrates the real (ε′) and the imaginary part (ε″) of the complex permittivity of the composite. Permittivity and permeability show a variation with the frequency. A resonance in the X-band frequency occurs because of the resonant frequency of electron hopping (Fe3+ ↔ Fe2+). The

High photocatalytic activity of V-doped SrTiO₃ porous nanofibers produced from a combined electrospinning and thermal diffusion process

• Panpan Jing,
• Wei Lan,
• Qing Su and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 1281–1286, doi:10.3762/bjnano.6.132

• ]. Although a promising photocatalytic candidate, the catalytic activity of SrTiO3 is still heavily influenced by its considerably large band gap of ≈3.25 eV and high dielectric permittivity [14]. The calculated band structure of SrTiO3 shows that the top of the valence band (VB) and the bottom of the

Attenuation, dispersion and nonlinearity effects in graphene-based waveguides

• Almir Wirth Lima Jr.,
• João Cesar Moura Mota and
• Antonio Sergio Bezerra Sombra

Beilstein J. Nanotechnol. 2015, 6, 1221–1228, doi:10.3762/bjnano.6.125

• part of the conductivity undergoes more changes in the region where the TE modes are located [14]. Starting from Maxwell’s Equations, we arrive at the expression that relates the electric permittivity of a graphene nanoribbon to the angular frequency (ω), conductivity and graphene effective thickness

• (t) of the graphene nanoribbon, given as [15][16]: In a graphene nanoribbon embedded in a substrate with relative permittivity εr, the TM modes are dominant. Considering the nonretarded regime (q >> ω/c, where c is the speed of light in air), the equation for the dispersion relation for graphene

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

• it. This effect can be included in the Simmons model by replacing the tip–sample separation z with the effective barrier width s: where the effective barrier width s is given by [18][28]: Here, a is given by with ε0 the electric permittivity of the vacuum and ζ a constant between 0 (two point charges

Interaction of electromagnetic radiation in the 20–200 GHz frequency range with arrays of carbon nanotubes with ferromagnetic nanoparticles

• Agylych Atdayev,
• Alexander L. Danilyuk and
• Serghej L. Prischepa

Beilstein J. Nanotechnol. 2015, 6, 1056–1064, doi:10.3762/bjnano.6.106

• permeability and permittivity of the nanocomposite taking into account the possible resistive, capacitive and inductive coupling between the components of the sample. Indeed, in the frequency range of tens or hundreds of GHz, the microwave properties of the nanocomposite should strongly depend not only on the

• expression: where µ1 and µ2 are the relative permeabilities of the carbon matrix and the ferromagnetic NPs respectively, a is the NP diameter, ω is cyclic frequency of EMR, µ0 is magnetic constant, and N is the volume NP concentration. For the permittivity, the following modified expression was deduced

• : where ε1 and ε2 are the relative permittivities of the carbon matrix and the NP, respectively, ε0 is permittivity of vacuum, and σ is the specific conductivity of CNT-based nanocomposite. The reflection coefficient is determined as where , and Z0 = 377 Ω is the characteristic impedance of the plane wave

Graphene quantum interference photodetector

• Mahbub Alam and
• Paul L. Voss

Beilstein J. Nanotechnol. 2015, 6, 726–735, doi:10.3762/bjnano.6.74

• volume of V, c is the speed of light, εr is the relative permittivity, μr is the relative permeability and ε is the absolute permittivity. The photon scattering functions, and , are calculated assuming monochromatic light and two energy levels for excitation. Both the acoustic phonon and optical phonon

Entropy effects in the collective dynamic behavior of alkyl monolayers tethered to Si(111)

• Christian Godet

Beilstein J. Nanotechnol. 2015, 6, 583–594, doi:10.3762/bjnano.6.60

• -dependent electric field. Dissipation (energy loss) mechanisms can be described by using equivalent representations of the complex admittance, including the dielectric permittivity ε* and electrical modulus M*. Dipole reorientation requires an activation of the system with energy barriers related either to

• C* = (Y*/jω) or the electrical modulus M* = (ε*)−1 = jω C0/Y* (here C0 = C*/ε* is arbitrarily set to 100 pF). The characteristic frequencies of the loss peaks in imaginary modulus, M″(ω), or in imaginary permittivity, ε″(ω), data correspond to a delay between the electric field and local charge

• −1 for ω >> ωDH, are fully consistent with Jonscher [42][43][44] and Havriliak–Negami [52][53] expressions. Fitting the four parameters (Δε, ωDH, mDH, nDH) for each relaxation mechanism is performed using the complex permittivity (Equation 1) by minimizing the error function EF(Δε, ωDH, mDH, nDH

Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Xabier Quintana and
• José M. Otón

Beilstein J. Nanotechnol. 2015, 6, 396–403, doi:10.3762/bjnano.6.39

• conditioning of the cell walls [12] and modified by application of external electric fields above a certain voltage called Freedericksz threshold. Depending on the applied voltage, the LC dielectric permittivity along the electric field varies since the LC director adopts a specific orientation in order to

• . Remarkable conductivity differences between CNT-doped and undoped LC cells have been reported, and studies about variations in the dielectric permittivity [14][15], threshold voltage [16] and response time [17][18] have been published. Yet a more detailed description of the electrical behavior of CNT-doped

• above mentioned operating frequency range, from 100 Hz to 10 kHz. As Cr is proportional to the dielectric permittivity, its value is expected to vary with the applied voltage upon reorientation of the material, due to the dielectric anisotropy of LC. For MWCNT-doped LC cells, one could also expect a