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The development of functionalized persistent-luminescent (PersL) materials is currently receiving intense interest for diverse applications. However, PersL materials emitting ultraviolet light in the 315–400 nm (UVA) range are lacking. Herein, a series of x-ray-activated PersL materials based on ABCO4-type structures with random cation arrangements are developed. Comprehensive experiments confirm that materials featuring random cation arrangements are sufficiently general to act as host materials for PersL. Experimental results indicate that as-synthesized SrLaXO4:Bi3+ (X = Al, Ga, In) powders have tunable PersL bands covering the UV-to-visible range after x-ray irradiation. Taking advantage of the depth-independent nature of x-ray illumination in tissues, UVA Persl composites using the matched photosensitizer g-C3N4 (SrLaAlO4:Bi@g-C3N4) are well suited for x-ray-activated photodynamic therapy, as proven by tests for singlet-oxygen (1O2) generation. Therefore, we suggest that the proposed concept be applied to discover additional functionalized PersL materials for clinical cancer therapy in the future. [ABSTRACT FROM AUTHOR]

The controlling effect of an electron injection on the electron energy distribution function (EEDF) and on the energetic electron flux, in a capacitive radio-frequency argon plasma, is studied using a one-dimensional particle-in-cell/Monte Carlo collisions model. The input power of the electron beam is as small as several tens of Watts with laboratory achievable emission currents and energies. With the electron injection, the electron temperature decreases but with a significant high energy tail. The electron density, electron temperature in the sheath, and electron heating rate increase with the increasing emission energy. This is attributed to the extra heating of the energetic electrons in the EEDF tail. The non-equilibrium EEDF is obtained for strong non-local distributions of the electric field, electron heating rate, excitation, and ionization rate, indicating the discharge has transited from a volume heating (a-mode dominated) into a sheath heating (c-mode dominated) type. In addition, the electron injection not only modifies the self-bias voltage, but also enhances the electron flux that can reach the electrodes. Moreover, the relative population of energetic electrons significantly increases with the electron injection compared to that without the electron injection, relevant for modifying the gas and surface chemistry reactions. [ABSTRACT FROM AUTHOR]

In this paper, we have presented an atomistic quantum simulation study to investigate the device performances of GaSb/InAs heterojunction tunnel field-effect transistors (TFETs) with nanometer body thicknesses. It is revealed that the thin junction induced quantum confinement effect results in a heterojunction type transition from type-III to type-II as the junction thickness reduces, which can be used as an effective modulation of the TFET device performance. It is found that as the channel thickness decreases, both the ON current and OFF current of the device decrease significantly due to the quantum confinement induced effective band gap enlargement. In addition, the OFF current of the heterojunction GaSb/InAs TFET is always larger than that of the homojunction InAs TFET, which is possibly caused by the GaSb/InAs interfacial state assisted tunneling. It is also revealed that the subthreshold swing of the heterojunction TFET does not change much as the channel thickness is reduced. [ABSTRACT FROM AUTHOR]

The study presents a model for electron tunneling through defects in an insulator. The results suggest that the introduced defects should lie in the middle of a reasonably thick insulator to improve the carrier energy selectivity.

Research was conducted to evaluate the error introduced by the use of acoustoelastic coefficients defined with the natural coordinates for the estimation of residual stresses. Two approaches were considered to estimate the differences between the acoustoelastic coefficients in function of the system of coordinates. A comparison of theoretical and experimental results show that the value of some coefficients can vary significantly according to the used system of coordinates.

We investigate the Andreev transports through a double-quantum-dot Cooper-pair splitter with an additional direct coupling between the dots. It is found that when finite magnetic flux is applied through this structure, its induced phase adjusts the local and crossed Andreev reflections in different manners. Moreover, in the presence of appropriate magnetic flux, the crossed Andreev reflection can be efficiently enhanced, accompanied by the suppression of the local Andreev reflection. Such a result exists in both the linear and nonlinear transport regions, even in the case of strong intradot Coulomb interaction. Therefore, such a work provides a promising scheme to enhance the splitting of the Cooper pair. [ABSTRACT FROM AUTHOR]

Rare earth (RE) doped materials have been widely exploited as the intriguing electronic configuration of RE ions offers diverse functionalities from optics to magnetism. However, the coupling of magnetism with photoluminescence (PL) in such materials has been rarely reported in spite of its fundamental significance. In the present paper, the effect of high pulsed magnetic field on the photoluminescence intensity of Eu3+-doped nano-glass-ceramics has been investigated. In our experiment, Eu-doped oxyfluoride glass and glass ceramic were prepared by the conventional melt-quenching process and controlled heat treatment. The results demonstrate that the integrated PL intensity of Eu3+ decreases with the enhancement of magnetic field, which can be interpreted in terms of cooperation effect of Zeeman splitting and magnetic field induced change in site symmetry. Furthermore, as a result of Zeeman splitting, both blue and red shift in the emission peaks of Eu3+ can be observed, and this effect becomes more prominent with the increase of magnetic field. Possible mechanisms associated with the observed magneto-optical behaviors are suggested. The results of the present paper may open a new gate for modulation of luminescence by magnetic field and remote optical detection of magnetic field. [ABSTRACT FROM AUTHOR]

We investigate the transport properties of a quantum dot (QD) chain side-coupled to a pair of Majorana bound states (MBSs). It is found that the zero-bias conductance is tightly dependent on the parity of QD number. First, if a Majorana zero mode is introduced to couple to one QD of the odd-numbered QD structure, the zero-bias conductance is equal to e²/2h, but the zero-bias conductance will experience a valley-to-peak transition if the Majorana zero mode couples to the different QDs of the even-numbered QD structure. On the other hand, when the inter-MBS coupling is nonzero, the zero-bias conductance spectrum shows a peak in the odd-numbered QD structure, and in the even-numbered QD structure one conductance valley appears at the zero-bias limit. These results show the feasibility to manipulate the current in a multi-QD structure based on the QD-MBS coupling. Also, such a system can be a candidate for detecting the MBSs. [ABSTRACT FROM AUTHOR]

Particle-in-cell/Monte Carlo collision simulations, coupled with an external circuit, are used to investigate the behavior of pulsed dual-frequency (DF) capacitively coupled plasmas (CCPs). It is found that the phase shift ϑ between the high (or low) frequency source and the pulse modulation has a great influence on the ion density and the ionization rate. By pulsing the high frequency source, the time-averaged ion density shows a maximum when ϑ=90°. The time-averaged ion energy distribution functions (IEDFs) at the driven electrode, however, keep almost unchanged, illustrating the potential of pulsed DF-CCP for independent control of ion density (and flux) and ion energy. A detailed investigation of the temporal evolution of the plasma characteristics indicates that several high frequency harmonics can be excited at the initial stage of a pulse period by tuning the phase shift ϑ, and this gives rise to strong sheath oscillations, and therefore high ionization rates. For comparison, the pulsing of the low frequency source is also studied. In this case, the ion density changes slightly as a function of time, and the time-averaged ion density shows the same trend as in the HF modulation for different phase shifts ϑ. Moreover, the time-averaged IEDFs at the driven electrode can be modulated, showing the potential to reduce the maximum ion bombardment energy. [ABSTRACT FROM AUTHOR]

Electron transport in an armchair graphene nanoribbon is theoretically investigated by considering the presence of one line defect. It is found that different-property Fano effects occur in electron transport through such a structure, which are determined by the nanoribbon width and the coupling manner between the line defect and the nanoribbon. The spectra of the density of electron states show that the line defect induces some localized quantum states around the Dirac point, and that the different localizations of these states lead to the abundant transport results. By analyzing the influence of the structure parameters, the Fano effects are described in detail. With the obtained results, we consider such a structure to be a promising candidate for nanoswitch. [ABSTRACT FROM AUTHOR]

Motivated by the result in the recent work [A. Slachter, F. L. Bakker, J.-P. Adam, and B. J. van Wees, Nature Phys. 6, 879 (2010)], we research the thermally driven electron transport through a quantum dot (QD) coupled to two ferromagnetic leads and one normal-metallic lead. By applying temperature bias between the two ferromagnetic leads, we calculate the charge and spin currents in the normal-metallic lead and the spin accumulation in the QD. As a result, we observe that the charge and pure spin currents in the normal-metallic lead, as well as the spin accumulation in the QD, can be independently driven by the temperature bias. According to these results, we propose this system to be a promising candidate of the nanoswitch for the charge and spin current manipulation. [ABSTRACT FROM AUTHOR]

The Fano effect in electron transport through a parallel-coupled multi-quantum-dot system is theoretically studied by adjusting the asymmetries of dot-lead couplings. As a result, we find that three kinds of Fano lineshapes emerge in the linear conductance spectra. Namely, when the dot-lead couplings are up-down asymmetric, two kinds of Fano effects occur with the tuning of local magnetic fluxes. The other Fano effect is observed in the case of left-right asymmetry of the dot-lead couplings, which is tightly dependent on the dot number. We then transform the Hamiltonian into molecular orbital representation and discuss the three kinds of Fano interference mechanisms in detail. It is observed that the coupling manners between the leads and molecular states are the key factors to induce the Fano antiresonance. Since the abundant Fano effects, we consider such a structure to be a candidate of a thermoelectric device. We believe that the numerical results help to understand the Fano effect of the parallel-coupled multi-quantum-dot structure. [ABSTRACT FROM AUTHOR]

By applying a symmetric dipolar spin battery in a parallel-coupled quantum-dot (QD) structure, the spin accumulation in the QDs is investigated. We find that the spin accumulation can be achieved via electrically adjusting the left-right antisymmetry of the QD-lead couplings or introducing different magnetic fluxes through the sub-rings of this system. And, the spin accumulation properties are closely dependent on the number of QDs in this structure. Compared with the electrical method, the magnetic method is more efficient to manipulate the spin accumulation. When the intradot Coulomb interaction is considered, the electrically induced spin accumulation is somewhat suppressed, but in the magnetic method the spin accumulation is efficiently enhanced. We believe that the results can be observed in the experiment of spintronics, which provides an alternative scheme for spin manipulation. [ABSTRACT FROM AUTHOR]

In this paper, we study the electron properties of an Aharonov-Bohm interferometer with an embedded quantum dot (QD) by considering the leads of spin bias. As a result, it is found that a local magnetic flux through the structure can efficiently induce spin accumulation in the QD, unaccompanied by any charge transfer, and it shows that the direction and magnitude of the spin accumulation are tightly dependent on the interplay between the magnetic flux and spin bias. Based on the calculated results, we propose such a structure to be a candidate of the spin-manipulating device. [ABSTRACT FROM AUTHOR]

By introducing local Rashba spin-orbit interaction in a three-terminal quantum dot ring, we calculate the currents induced by thermoelectric effect. It shows that, when a temperature bias is applied between the source and drains, there emerge apparent spin currents in the two drains. We find, via adjusting the structure parameters, that an electron from the source will choose its drain according to its spin index. Due to the advances in nanodevice fabrication, this structure can be constructed, and then we believe that it can be a candidate of the spin-manipulating device. [ABSTRACT FROM AUTHOR]

We present a new empirical pseudopotential (EPM) calculation approach to simulate the million atom nanostructured semiconductor devices under potential bias using periodic boundary conditions. To treat the nonequilibrium condition, instead of directly calculating the scattering states from the source and drain, we calculate the stationary states by the linear combination of bulk band method and then decompose the stationary wave function into source and drain injecting scattering states according to an approximated top of the barrier splitting (TBS) scheme based on physical insight of ballistic and tunneling transports. The decomposed electronic scattering states are then occupied according to the source/drain Fermi-Levels to yield the occupied electron density which is then used to solve the potential, forming a self-consistent loop. The TBS is tested in a one-dimensional effective mass model by comparing with the direct scattering state calculation results. It is also tested in a three-dimensional 22 nm double gate ultra-thin-body field-effect transistor study, by comparing the TBS-EPM result with the nonequilibrium Green's function tight-binding result. We expected the TBS scheme will work whenever the potential in the barrier region is smoother than the wave function oscillations and it does not have local minimum, thus there is no multiple scattering as in a resonant tunneling diode, and when a three-dimensional problem can be represented as a quasi-one-dimensional problem, e.g., in a variable separation approximation. Using our approach, a million atom nonequilibrium nanostructure device can be simulated with EPM on a single processor computer. [ABSTRACT FROM AUTHOR]

Recently a so-called electrical asymmetry effect (EAE), which could achieve high-degree separate control of ion flux and energy in dual-frequency capacitively coupled radio-frequency (CCRF) discharges, was discovered theoretically by Heil et al. [J. Phys. D: Appl. Phys. 41, 165202 (2008)] and was confirmed by experiments and theory/numerical simulations later on for electropositive argon discharges. In this work simulations based on particle-in-cell/Monte Carlo collision are performed to study the EAE on electronegative oxygen plasmas in geometrically symmetric CCRF discharges. Dual frequency discharges operating at 13.56 and 27.12 MHz are simulated for different pressures and the results are compared with those of electropositive argon discharges at the same conditions. It is found that in general the EAE on oxygen discharges has similar behavior as on argon discharge: The self-bias voltage η increases monotonically and almost linearly with the increase in the phase angle θ between the two driving voltages in the range 0<θ<90°, and the maximum ion energy varies by a factor of 3 by adjusting θ. However, the ion flux varies with θ by ±12% for low pressure and by ±15% for higher pressure, due primarily to an enhanced plasma series resonance, which then leads to dramatic changes in plasma density, power absorption and consequently the electronegativity. This may place a limitation for achieving separate control of ion energy and flux for electronegative plasma via the EAE. [ABSTRACT FROM AUTHOR]

The impurity-modulated electron transport properties in a double quantum dot (QD) Aharonov-Bohm ring are theoretically studied, by considering impurities locally and nonlocally coupled to the QDs in the ring arms, respectively. It is found that the impurities influence the electron transport in a nontrivial way: in the case of zero magnetic flux, a single-level impurity leads to the appearance of Fano line shapes in the conductance spectra, and the positions of Fano antiresonances are determined by both the impurity-QD couplings and the QD levels separated from the Fermi level; whereas when a magnetic flux is introduced with the phase factor [lowercase_phi_synonym]=π the Breit-Wigner line shapes appear in the conductance curves. Compared with the local-impurity case, nonlocal impurities alter the conductance period versus the magnetic flux. In addition, when many-body effect is considered within the second-order approximation, we find the important role of the Coulomb interaction in modifying the electron transport. [ABSTRACT FROM AUTHOR]

Magnetic nanofluids possess some unique properties that can significantly affect their thermal conductivity. We synthesize monodispersed magnetite (Fe3O4) nanofluids in toluene with the particle size from 4 to 12 nm and obtain aqueous nanofluids by a simple 'one-step' phase transfer. Even without the effect of external field, the magnetic-interaction-induced self-assembled aggregation can still be significant in magnetite nanofluids. Investigation of the microstructures of self-assembled aggregation is carried out by the dynamic light scattering, which unveils the variation of aggregated configurations with particle concentration and time. Based on the calculation from the existing models, the aggregates decrease the thermal conductivity of both themselves and the entire system, mainly due to the less solid contents and weaker mobility compared with the single particles as well as the increase in interfacial thermal resistance. As the manifestation of the aggregation-structure variation, the measured thermal conductivity is of a wavelike shape as a function of particle concentration. The particle coating layers are also of importance in cluster formation so that nanofluid thermal conductivity can be manipulated for some nanofluids by changing the stabilizer used and thus controlling the particle aggregated structures. Due to the effects of temperature, viscosity and coating layers, the thermal conductivity for aqueous system varies in a different way as that for the toluene system. [ABSTRACT FROM AUTHOR]

The laser induced damage threshold (LIDT) has become a technical bottleneck which restricts the application and development of the inertial confinement fusion. Using single point diamond turning method to process KH2PO4 (KDP) crystals, the periodic microwaviness will be left on the machined surface which has a significant impact on the LIDT. In this paper, after acquiring the frequency information of machined surface of KDP crystals with the power spectral density method, we analyze quantitatively the influence of microwaviness on the LIDT of KDP crystal with the Fourier modal theory. Research results indicate that: the surface morphology of KDP crystal is consisted of the subwaviness with different characteristic spatial frequencies; and the reduced amount of the LIDT of KDP crystal leaded by such subwaviness is different; the experimental results of the LIDT are consistent with the theoretical calculations basically; for the machine tool and the processing technology we used, the leading frequency of microwaviness which caused the LIDT decreasing is between (350 μm)-1 and (30 μm)-1, especially between (90 μm)-1 and (180 μm)-1. [ABSTRACT FROM AUTHOR]

Quantum dot superlattices offer prospects for new generations of semiconductor devices. One possible recently suggested application is in tandem solar cells based entirely on silicon, using confinement in the quantum dot to control the cell band gap. In this paper, we use the effective mass approach to calculate the conduction band structure of a three-dimensional silicon quantum dot superlattice with the dots embedded in a matrix of silicon dioxide, silicon nitride, or silicon carbide. The quantum dot superlattice is modeled as a regularly spaced array of equally sized cubic dots in the respective matrix. Incorporating the effect of silicon anisotropic effective mass is shown to reduce both the degeneracies of the isotropic solutions and the energy separation between states. Electron densities of state and mobilities are derived from the band structure data. Theoretical results for the effect of dot size, interdot distance, and matrix material have been obtained. These results clarify the required design features of silicon quantum dot superlattices for the proposed all-silicon tandem solar cells. [ABSTRACT FROM AUTHOR]

Several studies are conducted to explain the various effects of period, as well as amplitude of microwaviness as exhibited on the laser induced damage threshold of the [KH.sub.2][PO.sub.4] crystals.

The atomistic pseudopotential quantum mechanical calculations are used for analyzing the transport in million atom nanosized metal-oxide-semiconductor field-effect transistors. A partition method and a quasi-Fermi level method are the two methods to occupy the electron eigenstates to yield the charge density in a nonequilibrium condition that are tested and compared.

The molecular-based magnetic materials A[Fe.sup.II][Fe.sup.III][([C.sub.2][O.sub.4]).sub.3] have a honeycomb structure in which [Fe.sup.II](S=2) and [Fe.sup.III])(S=5/2) have occupied sites alternatively and they are described by mixed spin-2 and spin-5/2 Ising model with ferromagnetic interlayer coupling. The effects of the biaxial crystal field on the magnetization, initial susceptibility and internal energy of the molecular-based system are studied.

A thermal emitter with selective wavelength is shown in which the dielectric layers formed one-dimensional photonic crystals are sandwiched between two Ag films. The selected thermal radiation of the photonic crystals resonates between two metal films and surface plasmon polaritons are generated on the top Ag and are converted to light radiation.

The couplings between different energy band valleys in a metal-oxide-semiconductor field-effect transistor (MOSFET) device are examined by using self-consistent calculations of million-atom Schrodinger-Poisson equations. The system eigenstates derived from different bulk valleys is calculated separately and this has reduced the simulation time because the diagonalization of the Hamiltonian matrix scales as the third power of the total number of basis functions.

A new approach for the fabrication of several polymer photonic crystal superprism structures using the elastomeric polydimethylsiloxane templates is discussed. The technique has been found to be extremely cheap, effective and high-yielding and hence finds applications in making photonic crystal based nanostructures.

The hysteresis loops and susceptibility of spin system with the crystal field are studied within the framework of the effective-field theory with the differential technique. The effects of the external longitudinal magnetic field on the magnetization and susceptibility are discussed in detail.

The refractive index change in Au(super+3) -doped silicate glasses irradiated by a femtosecond laser and successive heat treatment is reported. The mechanism of the refractive index and other observed phenomenon are discussed.