Single Electronic Oscillator Research Articles

Terahertz resonant-tunneling-diode oscillator with two offset-fed slot-ring antennas

We proposed and fabricated a terahertz resonant-tunneling-diode oscillator integrated with two offset slot-ring antennas for high-output power and high-directivity radiation. In this device, the length of the antenna, approximately half the wavelength of the oscillation frequency, enables efficient terahertz radiation. The increased radiation conductance, resulting from the offset and the two slot-ring antennas, enables higher output power. Additionally, radiation directivity can be improved by using two slot-ring antennas. The fabricated device generated high-power oscillation of 1.29 mW at 412 GHz. This is the highest output power of a single electronic device oscillator in the 400 GHz range.

Experimental Demonstration of Multiband Comb-Enabled mm-Wave Transmission

A novel system architecture to realize multiple synchronized sources for multiband millimeter-wave (mm-Wave) transmission has been designed and experimentally demonstrated in two of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$</tex-math> </inline-formula> -band subbands at 100 and 112.5 GHz. The technique converts a distributed electro-optic comb, generated off-site, to a local electrical comb. The higher frequency tones in the resulting comb are extracted and used as mm-Wave oscillator sources. Thus, the architecture provides a method to generate multiple frequency-synchronized sources, using only a single electronic oscillator, with exceptionally low phase noise for simultaneous multiband mm-Wave transmission. Additionally, a lower frequency tone at 6.25 GHz is broadcasted over the air, providing synchronization reference between the mm-Wave transmitters and receivers.

Single and double electron excitation transition rates and oscillator strengths calculations in the study of the x-ray absorption spectrum of Neon

We report a new study of the x-ray absorption spectrum of Neon near the K-edge and near the KL-edge. The study is performed by calculating the transition probabilities and oscillator strengths for excitations from the ground state to singly and doubly excited states, the calculations were performed using multi-configurational Dirac-Fock (MCDF) method. Breit interaction between electrons and finite nuclear size effects were taken into account during the calculations, the transition probabilities were convoluted into Lorentzian line shape profiles. The results of the calculations were then compared to previous measurements of the x-ray absorption spectrum of Neon, good agreement was observed and many features in the spectrum were explained.

Quantum Level Instability of Transverse Excitation in Electron Flow

In current research, we use the effective Schrödinger-Poisson model to study a new kind of quantum-level instability in an infinite-wall slab electron flow. We use the Madelung fluid representation along with the conventional eigenvalue problem techniques in order to solve the linearized coupled differential equations representing the linear transverse collective excitations in the electron gas of arbitrary degree of degeneracy having a constant perpendicular drift. It is shown that the energy levels of collective electrostatic excitations are doubly quantized due to mutual interactions between single electron oscillations, analogous to the problem of a particle in a box, and collective Langmuir oscillations, which are modulated over single electron quantum state. We also report the transverse excitation instability of plasmon energy level in electron slab flow due to the interplay between the wave-like dispersion and the destabilizing perpendicular electron drift momentum. We further study in detail the parametric dependence of such instability in terms of different aspects of the many-electron system. Such a quantum-level instability may have important applications in characteristic behavior of plasmonic devices and their frequency response. Parametric quantization of drifting electron fluid may also have broad applications in nanoscale quantum device calibration and quantum measurements.

Experimental 3-dimensional tracking of the dynamics of a single electron in the Fermilab Integrable Optics Test Accelerator (IOTA)

We present the results of experimental studies on the transverse and longitudinal dynamics of a single electron in the IOTA storage ring. IOTA is a flexible machine dedicated to beam physics experiments with electrons and protons. A method was developed to reliably inject and circulate a controlled number of electrons in the ring. A key beam diagnostic system is the set of sensitive high-resolution digital cameras for the detection of synchrotron light emitted by the electrons. With 60–130 electrons in the machine, we measured beam lifetime and derived an absolute calibration of the optical system. At exposure times of 0.5 s, the cameras were sensitive to individual electrons. Camera images were used to reconstruct the time evolution of oscillation amplitudes of a single electron in all 3 degrees of freedom. The evolution of amplitudes directly showed the interplay between synchrotron-radiation damping, quantum excitations, and scattering with the residual gas. From the distribution of measured single-electron oscillation amplitudes, we deduced transverse emittances, momentum spread, damping times, and beam energy. Estimates of residual-gas density and composition were calculated from the measured distributions of vertical scattering angles. Combining scattering and lifetime data, we also provide an estimate of the aperture of the ring. To our knowledge, this is the first time that the dynamics of a single electron are tracked in all three dimensions with digital cameras in a storage ring.

Effect of quantum charge screening on dual plasmon scattering

In this paper, we investigate the resonant scattering of driven linear oscillations in an isothermal electron gas with an arbitrary degree of degeneracy. The coupled pseudoforce system is obtained from the quantum hydrodynamic model and is extended to include the driving pseudoforce and pseudodamping effect in order to study the quantum charge shielding on the resonant scattering, heat capacity, and Friedel oscillations around an impurity charge. It is shown that the resonant scattering phenomenon takes place when the driver wavelength matches either scale lengths of plasmon excitations, which arise due to single electron oscillations and collective electron plasma excitations. It is remarked that in the presence of a periodic density structure such as in metals, plasmon interactions with a periodic lattice structure can lead to resonant Bragg-like scattering. A generalized energy dispersion relation for pseudodamped plasmon excitations is obtained, which indicates a critical screening point beyond which the plasmon excitations behave only particlelike. It is shown that the heat capacity of plasmon excitations and the static quantum charge screening are strongly affected by interaction between the plasmon and the charge screening scale lengths.

The impact of thickness on the optical, electrical and dielectric properties of nanocrystalline 0.9 MTO-0.1BNO composite thin films

Abstract The 0.9 MgTiO3–0.1Ba5Nb4O15 (0.9MTO-0.1BNO) thin films deposited on Pt (111)/TiO2/SiO2/Si (100) and SiO2 substrates by RF reactive magnetron sputtering have been reported. The films are deposited at a substrate temperature of 400 °C under 50/50 argon (Ar2)/oxygen (O2) mixed ambiance by varying the film thickness. The X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) studies have confirmed presence of both MTO and BNO phases.. The obtained strain in the films is found to be reduced with an increase in film thickness. The 3d crystal structure of MTO exhibited significant variations in bond length for the films with different thicknesses. The dispersion in the refractive index of the films has obtained using the single electronic oscillator model, and the obtained bandgap value is found to be reduced from 3.75 to 3.34 eV with an increase in film thickness from 150 to 340 nm, accordingly. The films revealed uniform spherical shaped particles with smooth surface with small rms roughness values around 2.9 to 2 nm. The microwave and low frequency dielectric responses showed improvment with an increase in film thickness. The impedance spectroscopy analysis displayed Cole-Cole behavior indicating the non-Debye conduction process present in the films. The frequency dependent conduction process has analyzed by Jonscher's Power law and the non-overlapping small polaron hopping nature has been observed. Extracted activation energies estimated from conductivity are found to be in the range of 0.31 eV to 0.14 eV. The leakage current density (J) with the applied potential has found to be in the range of 10−6 A/cm2 at 100 kV/cm2 for 340 nm film. The obtained results suggest that these films are promising for optical and microwave integrated circuit applications.

Characteristics of plasmon transmittivity over potential barriers

In this research, we consider plasmon tunneling through the intrinsic chemical potential barriers using the Schrödinger-Poisson model. The Schrödinger-Poisson system is reduced to the linear coupled pseudoforce system, and the electrostatic as well as wavefunction solutions are derived and used to obtain the transmittivity and reflectivity of plasmon excitations through the double and triple metallic barriers with various parameter settings. It is remarked that the choice of chemical potential (Fermi energy for metals) in quantum barriers has a significant effect on the transmission amplitude of collective electron excitations. For triple metallic barriers, it is found that the transmittivity spectrum possesses distinct transmission valleys in the energy spectrum, which may be attributed to the interactions of single-electron oscillations with the collective electrostatic excitations. Current research can have important applications in fast quantum tunneling devices with intrinsic chemical potential barriers and helps in the development of rapidly growing fields of plasmonics and nanometallic technology.

Electronic structure with dipole moment and rovibrational calculations of the MgLi and MgNa molecules

We investigate an orderly study of the adiabatic potential energy curves for 29 and 30 low-lying 2s+1Λ+/− electronic states of the molecules MgLi and MgNa, respectively. The calculation has been done by using the complete active space self-consistent field followed by multi-reference configuration interaction with Davidson correction. For the investigated electronic states, the static and transition dipole moment curves are calculated along with the Einstein coefficients, the emission oscillator strength, the spontaneous radiative lifetime, the line strength, the classical radiative decay rate of the single-electron oscillator, the spectroscopic constants (Te, ωe, ωexe, Be, Re), and the equilibrium dissociation energy De. By means of the canonical functions approach, the ro-vibrational constants Ev, Bv, Dv, and the abscissas of the turning points, Rmin and Rmax, have been calculated for the considered electronic states up to the vibrational level v = 79. The Franck–Condon factors have been calculated and plotted for the transition between the low-lying electronic states of the two considered molecules. A good agreement is revealed between our calculated values and those available in the literature. Fifty new electronic states are investigated in the present work for the first time.

Microstructure and optoelectronic properties of gallium–magnesium codoped zinc oxide thin films by magnetron sputtering technique

The gallium–magnesium codoped zinc oxide (GMZO) thin films were deposited on glass substrates by radio frequency magnetron sputtering technique in an argon atmosphere. The influence of substrate temperature on the microstructure, morphology and optoelectronic properties of thin films was investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, four-point probe and spectrophotometry. It is found that all the deposited films have a hexagonal structure and a preferred orientation along the c-axis perpendicular to the substrate. As the substrate temperature increases, the dislocation density, lattice strain and electrical resistivity decrease initially and then increase, while the average crystallite size, average visible transmittance and figure of merit exhibit the reverse variation trend. The GMZO thin film deposited at the substrate temperature of 570 K possesses the best optoelectronic properties, with the largest average crystallite size of 52.05 nm, the lowest dislocation density of 3.69 × 1014 lines m− 2, the minimum lattice strain of 1.10 × 10− 3, the lowest electrical resistivity of 1.62 × 10− 3 Ω cm, the highest average visible transmittance of 88.63% and the maximum figure of merit of 5.11 × 103 Ω−1 cm− 1. The optical energy gaps of the films were evaluated by extrapolation method and observed to be in the range of 3.34–3.55 eV. Furthermore, the complex refractive index, the complex dielectric constant and the dissipation factor were determined by optical characterization methods, and the dispersion behaviour of refractive index was studied in terms of the single electronic oscillator model. The results show that the microstructure and optoelectronic properties of the GMZO thin films are dependent on substrate temperature.

Growth of hierarchical strontium incorporated cadmium sulphide for possible application in optical and electronic devices

In this work, we have incorporated strontium (Sr) into cadmium sulphide (CdS) complex to explore its effect on optical and electrical properties. In this regard Sr composited CdS and a bared CdS were prepared by hydrothermal technique. X-ray diffraction pattern of the materials were analyzed to obtain their crystalline structure, size and internal lattice strain. The compositional details were obtained from SEM-EDAX study. The optical properties of the films of synthesized materials were analyzed. The dependency of refractive index on incident photon energy was studied in detail for each material. The dispersion energy related parameters, dielectric relaxation constant and optical conductivity followed by dispersion of the refractive index were determined and discussed by employing the single electronic oscillator model. From wavelength dependent refractive index data, the plasma frequency, ratio of free charge carrier concentration to effective mass, lattice dielectric constant and high frequency dielectric constant were calculated to determine the discrepancy of the compounds. The third order optical susceptibility was analyzed to check their potential ability of performance in optical limiter and optical switching device application. The electrical characterization was performed by measuring the current–voltage characteristics of structure ITO/CdS:Sr/Al and ITO/CdS/Al. The rectifying I–V showed improved On/Off ratio under dark (25.03 and 19.98) and light (35.51 and 25.09) for ITO/CdS:Sr/Al compared to ITO/CdS/Al. The dark and photoconductivity of the film were also determined for both the films. The time dependent current response was analyzed at constant bias voltage ±1 V.

Design of thermal-noise-harnessing single-electron circuit for efficient signal propagation

We propose a new single-electron (SE) circuit that can improve the signal propagation speed by harnessing thermal noise efficiently. Generally, an SE circuit has some weaknesses. It is very sensitive to thermal noise and it takes a long time for signal propagation. To solve these problems, we focus on a unique function at an output terminal (an axon) of a neuron that can improve the signal propagation speed because of its distinctive structure. It is expected that a new high-speed SE circuit can be realized by mimicking the structure of the neuron. Here, we indicate the possibility of improving the signal propagation speed by harnessing the thermal noise in one-dimensional neuromorphic single-electron oscillators. Moreover, we designed a two-dimensional neuromorphic single-electron oscillator as an advanced circuit and confirmed its tolerance to thermal noise. Our study will be useful for constructing novel devices that actively use noise energy in the future.

Effect of working pressure on the structural, optical and electrical properties of titanium-gallium co-doped zinc oxide thin films

The transparent conducting titanium-gallium co-doped zinc oxide (TGZO) thin films were grown on glass substrates by radio-frequency magnetron sputtering technique. The effects of working pressure on the structural, optical and electrical properties of the films were investigated. The results show that the deposited films are polycrystalline with a hexagonal wurtzite structure and highly textured along the c-axis perpendicular to the substrate. The TGZO film prepared at the working pressure of 0.4 Pa exhibits the best crystallinity, the maximal grain size, the highest transmittance, the lowest resistivity and the highest figure of merit. The optical constants of the films were calculated using the method of optical spectrum fitting. The dispersion behavior of the films was studied by the single-electronic oscillator dispersion model. The oscillator parameters and optical bandgaps were determined. The results demonstrate that the microstructure and optoelectrical properties of the TGZO films are dependent on the working pressure.

Microstructural and optoelectronic properties of rf magnetron sputtered ZnO:(Ga,Ti) semiconductor thin films

Applying radio-frequency (rf) magnetron sputtering technique, Ga–Ti co-doped ZnO [ZnO:(Ga,Ti)] transparent conductive oxide films were deposited onto glass substrates. The films were characterized by X-ray diffraction, four-point probe and UV–visible spectrophotometer. The influence of sputtering pressure on microstructure and optoelectronic properties of the films was investigated. The results show that all the films are polycrystalline with a hexagonal wurtzite structure and grow preferentially in the (002) direction. The ZnO:(Ga,Ti) films deposited at sputtering pressure of 0.4 Pa exhibit the maximum grain size of 86.6 nm, the highest transmittance of 85.9 %, the lowest resistivity of 1.67 × 10−3 Ω cm, and the highest figure of merit of 1.38 × 10−2 Ω−1. The optical constants such as refractive index, extinction coefficient, dielectric constant and dissipation factor were determined using the method of whole optical spectrum fitting. Meanwhile, the dispersion behaviour of the films was studied by the single electronic oscillator model. The oscillator parameters and optical energy gaps were achieved. The results demonstrate that the microstructure and optoelectronic properties of the films are closely related to the sputtering pressure.

Microstructural and optoelectrical properties of transparent conducting ZnO:Al thin films for organic solar cells

AbstractThe Al‐doped zinc oxide (ZnO:Al) thin films were grown on glass substrates by the magnetron sputtering technique. The films were characterized with X‐ray diffractometer, four‐point probe and optical transmission spectroscopy, respectively. The dependence of microstructural, electrical and optical properties on deposition temperature was investigated. The results show that all the films have hexagonal wurtzite structure with highly c‐axis orientation. And the microstrural and optoelectrical properties of the films are observed to be subjected to the deposition temperature. The ZnO:Al film prepared at the deposition temperature of 650 K possesses the best optoelectrical properties, with the lowest electrical resistivity (6.1×10−4 Ω·cm), the highest average visible transmittance (85.3%) and the maximum figure of merit (0.41 Ω−1). The optical energy gap of the films was estimated from Tauc's law and observed to be an increasing tendency with the increment of the deposition temperature. Furthermore, the refractive index of the films was determined by the optical characterization methods and the dispersion behavior was studied by the single electronic oscillator model.

Charge fluctuations in single-electron tunneling oscillations

It has been predicted that in the presence of a sufficiently high-dissipative environment transport in a small tunnel junction can become extremely regular, giving rise to the phenomenon of single-electron tunneling oscillations. Recent progress in detection of high-frequency current fluctuations and the interest in single-electron sources motivate further investigations on the expected accuracy of the charge oscillations as a function of the impedance of the environment. In this paper we study theoretically the charge-fluctuation spectrum at finite frequency for the system at hand, and investigate its evolution as a function of the external impedance. The evolution and the disappearance of the single-electron oscillations peak is described by analytical and numerical methods.

Conduction Bottleneck in Silicon Nanochain Single Electron Transistors Operating at Room Temperature

Single electron transistors are fabricated on single Si nanochains, synthesised by thermal evaporation of SiO solid sources. The nanochains consist of one-dimensional arrays of ∼10 nm Si nanocrystals, separated by SiO2 regions. At 300 K, strong Coulomb staircases are seen in the drain–source current–voltage (Ids–Vds) characteristics, and single-electron oscillations are seen in the drain–source current–gate voltage (Ids–Vgs) characteristics. From 300–20 K, a large increase in the Coulomb blockade region is observed. The characteristics are explained using single-electron Monte Carlo simulation, where an inhomogeneous multiple tunnel junction represents a nanochain. Any reduction in capacitance at a nanocrystal well within the nanochain creates a conduction “bottleneck”, suppressing current at low voltage and improving the Coulomb staircase. The single-electron charging energy at such an island can be very high, ∼20kBT at 300 K.

Study on Optical Constants and Refractive Index Dispersion of Neutral red Doped Polymer Film

Problem statement: The some optical constants polymer thin film with red dye 3-amino-7-dimethylamino-2-methyl phenazine (NR) as the guest material and Polyvinylpyrrolidone (PVP) as the host material were prepared by adulteration and spin-coating methods. Approach: The values of some important parameters (refractive index n, extinction coefficient K and dielectric constant ε∞) of polymer thin film are determined from these spectra. Results: It has been found that the dispersion data obey the single oscillator relation of the Wemple-DiDomenico model, from which the dispersion parameters and high-frequency dielectric constant were determined. The estimation of the E0, Ed and ε∞ are 1.27, 3.175 and 3.5 eV respectively. Conclusion: The single oscillator model was used to calculate their optical constants from the transmittance and reflectance spectra. The dispersion of the refractive index in film follow the single electronic oscillator mode relation. The UV-Visible spectroscopic studies showed that, the NR film have high refractive index and high dielectric constant. The variation of the dielectric constant with the wavelength indicates that some interactions between photon and electrons in the films are produced in this wavelength range. These interactions are observed on the shapes of the real and imaginary parts of the dielectric constant and they cause the formation of peaks in the dielectric spectra which depends on the material type.

Structure and refractive index dispersive behavior of potassium niobate tantalate films prepared by pulsed laser deposition

Pure perovskite phase and crack-free KTa 0.5Nb 0.5O 3 thin films were prepared on Pt/Ti/SiO 2/Si substrates by pulsed laser deposition. The structure and orientation were analyzed by X-ray diffraction. The optical properties were investigated by an ellipsometer. The relationship between the refractive index dispersive behavior and internal structure was analyzed by Sellmeier dispersion model and single electronic oscillator approximation. The parameters of room temperature monomial Sellmeier oscillator were calculated. And the refractive index dispersive parameter E 0/ S 0 of KTa 0.5Nb 0.5O 3 thin films on Pt/Ti/SiO 2/Si substrates is (6.72 ± 0.04) × 10 −14 eV m 2, which is consistent with those of KTN crystals and compounds with ABO 3 perovskite type structure.

Third-order optical nonlinear absorption in Bi 1.95La 1.05TiNbO 9 thin films

Single phase Bi 1.95La 1.05TiNbO 9 (LBTN-1.05) thin films with a layered aurivillius structure have been fabricated on fused silica substrates by pulsed laser deposition at 700 °C. The X-ray diffraction pattern revealed that the films are single-phase aurivillius. The band gap, linear refractive index and linear absorption coefficient were obtained by optical transmittance measurements. The film exhibits a high transmittance (> 70%) in visible-infrared region and the dispersion relation of the refractive index vs. wavelength follows the single electronic oscillator model. The nonlinear optical absorption property of the film was determined by the single beam Z-scan method using 800 nm with a duration of 100 fs. A large positive nonlinear absorption coefficient β = 5.95 × 10 − 8 m/W was determined experimentally. The results showed that the LBTN-1.05 is a promising material for applications in absorbing-type optical devices.