Solid-state Plasma Research Articles

Analysis of dielectric function and dynamic structure factor of a multi-component plasma in a wurtzite GaN

We investigated dielectric responses of a multi-component plasma at finite temperature and applied the results to spectral analysis of dynamic structure factor of a photo-generated high density plasma in a wurtzite GaN. The behavior of effective dielectric function and dynamic structure factor in energy loss measurement are examined focusing to the effects of dynamic screening of carriers in the plasma. Features of their spectral behavior are illustrated including the roles of various elementary excitations in the three-component solid state plasma.

Analytic models for solid state plasma of Si/Ge/Si heterogeneous and lateral SPiN diode

Silicon-based reconfigurable antenna, which is fabricated by heterogeneous and lateral surface PiN (SPiN), is an effective technology to achieve antenna miniaturization and enhance radar and wireless communication system performance. In this paper, the heterogeneous and lateral Si/Ge/Si SPiN diode is presented, that can weaken the band gap narrowing of the P + and N + region to improve the injection ratio of PN junction. And the electrical properties of the solid state plasma within the intrinsic region are also studied. Based on the bipolar diffusion model and Fletcher boundary condition, the analytic models of the junction voltage, the current density and the solid state plasma concentration distribution are established for a large injection current, and the numerical simulation has been carried out. Results show that the junction voltage increases linearly with the increase of applied voltage and the solid state plasma concentration at the boundary; and the current density increases exponentially with increasing junction voltage and the applied voltage, respectively. And the applied voltage and the current density of heterogeneous SPiN diode is lower than that of homogeneous SPiN diode under the same condition due to the difference of barrier heights between the heterojunction and homojunction. In addition, results also show that the value of the concentration decreases with increasing length of the intrinsic region; otherwise, it increases with increasing applied voltage and the doping concentration in the P+ and N+ regions. Under the same conditions, the solid state plasma concentration of the heterogeneous SPiN diode is nearly seven times that of homogeneous diode, which is in excellent agreement with the data published, giving the evidence for the validity of our method. The proposed models provide an effective reference for the design and application of silicon-based reconfigurable antennas.

Spectral analysis on a phonon spectral function of a solid-state plasma in a doped semiconductor

We report an analysis on a phonon spectral function of a solid-state plasma formed in a doped semiconductor. Real and imaginary parts of phonon propagators are evaluated including carrier screening effects within a random phase approximation, and finite-temperature spectral behavior of the phonon spectral function is examined in terms of plasmon-phonon coupled modes and quasiparticle excitation mode of the plasma. The results are applied to the case of conduction electrons in a wurtzite GaN considering carrier-phonon coupling channel via polar optical phonons. We show that the dispersion relations of the plasmon-LO phonon coupled (‘upper’ and ‘lower’) modes and the character of the additional modes via single quasiparticle excitations are heavily associated with the nonlocal and dynamic behavior of the energy shift and collisional broadening of the dressed phonon propagator of the plasma.

Calculation of distribution of potential and electron concentration in the dust-electron thermal plasma with the axial geometry particles

We obtained the equation, which describes the distribution of the potential and the electron density in an equilibrium dust-electron plasma taking into account parameters of the electron gas inside the axial geomtry dust particles. The inclusion of these parameters performed on the basis of the model of "solid-state plasma," considering the condensed particle system as the ion core and the free electron gas.

Influence of metal macroparticles to the electron density in a dusty plasma

We obtained the equation, which describes electron density in an equilibrium dusty plasma taking into account parameters of the electron gas inside the dust particles. The inclusion of these parameters performed on the basis of the model of "solid-state plasma," considering the condensed particle system as the ion core and the free electron gas. The shape of potential barrier at the particle surface assumed as a rectangular.

Experimental testing of SiNx/SiO2 thin film filters for a concentrating solar hybrid PV/T collector

Achieving high temperature thermal outputs from concentrating photovoltaic/thermal (PV/T) systems presents a challenge in that the performance of the PV cells declines with increasing temperature. Spectral beam splitting is an attractive approach to address this conflict by thermally decoupling the PV and thermal receivers, allowing the PV cells to operate at low temperature and the thermal receiver to operate at high temperature. In this study, SiNx/SiO2 multilayer thin film filters were designed and fabricated to act as beam splitting devices in a 10 sun, linear Fresnel mirror-based, concentrating PV/T solar collector. In this collector, reflected light is directed to a silicon PV cell whilst the transmitted light is directed to a thermal receiver. Plasma-enhanced chemical vapor deposition (PECVD) was used to fabricate the filters which were designed to obtain maximum hybrid output. The resulting devices have high reflectance (greater than 95%) for light between 713 and 1067 nm and high transmittance (greater than 90%) for sunlight outside that reflection window. The concentration of process gases in the PECVD reactor was varied in order to reduce undesired absorption at short wavelengths –lower than 650 nm– by the SiNx layers. Indoor testing was carried out for the filters in a system which consists of a Si PV cell, a thermal sensor, and a solid-state plasma light source (6500 K black body spectrum). This study tested filter performance for various angles of incidence (AOI) between 20 and 45°. The experimental results indicate that the PV cells, illuminated with the reflected light from the filters, operate on average at 9.2% absolute higher efficiency than the same cells without the filter. Furthermore, for the best filter, in terms of relative percentage, the measured hybrid output (weighted by a worth factor of electrical vs. thermal energy) is ∼9% higher than the electrical output of a PV cell stand-alone system exposed to the same light source. This paper represents the first study of a hybrid PV/T solar collector using SiNx/SiO2 thin film filters and demonstrates the feasibility of such systems. This study also indicates that this type of system can utilize 85.6% of the incoming solar spectrum based on the measured optical properties of the filters.

Functionally Graded Dual-nanoparticulate-reinforced Aluminium Matrix Bulk Materials Fabricated by Spark Plasma Sintering

Functionally graded (FG) carbon nanotubes (CNT) and nano-silicon carbide (nSiC) reinforced aluminium (Al) matrix composites have been successfully fabricated using high-energy ball milling followed by solid-state spark plasma sintering processes. The CNTs were well-dispersed in the Al particles using the nSiC as a solid mixing agent. Two different types of multi-walled CNTs were used to add different amounts of CNTs in the same volume. The ball milled Al–CNT–nSiC and Al–CNT powder mixtures were fully densified and demonstrated good adhesion with no serious microcracks and pores within an FG multilayer composite. Each layer contained different amounts of the CNTs, and the nSiC additions showed different microstructures and hardness. It is possible to control the characteristics of the FG multilayer composite through the efficient design of an Al–CNT–nSiC gradient layer. This concept offers a feasible approach for fabricating the dual-nanoparticulate-reinforced Al matrix nanocomposites and can be applied to other scenarios such as polymer and ceramic systems.

On the ordinary mode and whistler mode instabilities in the degenerate anisotropic plasmas

Employing Vlasov-Maxwell set of equations, we have investigated the O-mode and whistler mode instability in a degenerate anisotropic magnetoplasma environment and compared the results to those reported for classical plasmas. We propose the excitation of a new banded type of instability for the O-mode case, which grows at some particular values of temperature anisotropy and external magnetic field. For the case of whistler wave, we observe instability saturation mechanism similar to the case of classical plasmas. The existence of both O-mode and whistler mode instability has been observed only for some specific range of unstable wavenumbers. The possible excitation of such instabilities in solid state plasma has been discussed, particularly for semiconductor and semimetal plasmas.

FPGA-based distributed computing microarchitecture for complex physical dynamics investigation.

In this paper, we present a distributed computing system, called DCMARK, aimed at solving partial differential equations at the basis of many investigation fields, such as solid state physics, nuclear physics, and plasma physics. This distributed architecture is based on the cellular neural network paradigm, which allows us to divide the differential equation system solving into many parallel integration operations to be executed by a custom multiprocessor system. We push the number of processors to the limit of one processor for each equation. In order to test the present idea, we choose to implement DCMARK on a single FPGA, designing the single processor in order to minimize its hardware requirements and to obtain a large number of easily interconnected processors. This approach is particularly suited to study the properties of 1-, 2- and 3-D locally interconnected dynamical systems. In order to test the computing platform, we implement a 200 cells, Korteweg-de Vries (KdV) equation solver and perform a comparison between simulations conducted on a high performance PC and on our system. Since our distributed architecture takes a constant computing time to solve the equation system, independently of the number of dynamical elements (cells) of the CNN array, it allows us to reduce the elaboration time more than other similar systems in the literature. To ensure a high level of reconfigurability, we design a compact system on programmable chip managed by a softcore processor, which controls the fast data/control communication between our system and a PC Host. An intuitively graphical user interface allows us to change the calculation parameters and plot the results.

Amplification of drifting semiconductor plasmons and effects of carrier collisions and diffusion

Carrier collisions and diffusion are the major mechanisms influencing loss in solid-state plasmas, and their understanding is crucial for the design of terahertz plasmonic oscillators and amplifiers. This paper presents an analysis of the role collisions and diffusion play in the amplification of plasmons reflecting from conducting boundaries in two-dimensional electron channels. The theoretical model relies on the hydrodynamic description of the electron dynamics, complete mode spectra and electrodynamic boundary conditions. Diffusion has been found to reduce the amplification coefficient due to a reduced asymmetry of the counter-propagating plasmons, and both collisions and diffusion have been found to influence the plasmon propagation loss. The distances of sustained amplification have been calculated and the implications for terahertz oscillators have been analysed.

Thermoelectric Performance of Multiple-Doped Co4Sb12−x−y−z Ge x Te y S z Skutterudite Compounds

CoSb3 skutterudites multiply doped with Ge, Te, and S were synthesized by solid-state reaction and spark plasma sintering. x-Ray diffraction studies revealed that Ge, Te, and S entered the lattice of the CoSb3 compounds, and while Te increased the lattice volume, Ge and S decreased it. Compared with the undoped and single-doped CoSb3 compounds, the thermal conductivity and lattice thermal conductivity are significantly suppressed due to greatly increased point defect scattering. It is found that S is more effective for decreasing the lattice thermal conductivity than Te and Ge. The highest thermoelectric figure of merit, ZT, exceeds 1.1 for the Co4Sb11.25Ge0.05Te0.63S0.07 compound at 800 K.

Synthesis, characterization and luminescent properties of Eu/Tb-doped LaSrAl3O7 nanophosphors

The synthesis of LaSrAl3O7 doped with rare earth (RE) ions Eu3+ and Tb3+ by a single-step solution combustion method has been demonstrated in the present investigation. The structural, morphological and luminescent properties were characterized by XRD, FT-IR, SEM, TEM and PL spectroscopy. The XRD results suggest that LaSrAl3O7 crystallize in a single phase having tetragonal structure with space group P421m. The transmission electron microscope (TEM) and scanning electron microscope (SEM) analysis show that the sample is made up of tetragonal particles with the size between 38 and 78nm. The photoluminescence properties of the samples were investigated by excitation and emission spectra. Under UV excitation (265nm), LaSrAl3O7: Eu3+ shows dominant peak at 619nm in addition to other characteristic peaks of Eu3+. Under 233nm excitation, the characteristic emissions corresponding to 5D3–7FJ (J=4–6) and 5D4–7FJ (J=3–6) transitions in LaSrAl3O7: Tb3+ nanophosphors are observed. These results indicate that Eu3+ and Tb3+ activated LaSrAl3O7 nanophosphors can be applied for tunable solid state laser materials and plasma display panels.

Enhancement of electrical transport through the anisotropic nanostructure performance of heavily Yb-doped PbSe0.2Te0.8 thin films

Solid-state microwave-assisted plasma technique was used to synthesize high-purity Pb1−xYbxSe0.2Te0.8 from initial components to obtain polycrystalline ingots with large grains. Pb1−xYbxSe0.2Te0.8 thin films were then deposited onto glass substrates using thermal evaporation in vacuum. The films have the polycrystalline rock salt-type (NaCl) structure. The crystal lattice parameters for the powders and thin films obtained from X-ray diffraction (XRD) patterns showed that the values of the lattice parameters increased with increasing Yb content. The field emission scanning electron microscopy images reveal that the Pb1−xYbxSe0.2Te0.8 thin films have uniform crystal grain sizes and dense nanostructures. The electrical transport properties of the thin films were measured in the temperature range of 298 K–523 K. The Seebeck coefficient of the films increased with x when x was in the range of 0.015–0.045, whereas it decreased for x between the range of 0.06 and 0.105. The carrier concentration was 4.3 × 1017 cm−3 for x = 0.015, and the maximum value was 6.34 × 1017 cm−3 at x = 0.075.

Infinite Conservation Laws for Nonlinear Integrable Couplings of Toda Hierarchy

We construct nonlinear integrable couplings of discrete soliton hierarchy, then the infinite conservation laws for the nonlinear integrable couplings of the lattice hierarchy are established. For explicit application of the method proposed, the infinite conservation laws of nonlinear integrable couplings of the Toda lattice hierarchy are presented. The obtained integrable couplings of the Toda lattice equations and conservation laws can be used to describe the possible formation mechanisms for hydrodynamics, solid state physics and plasma physics, respectively.

Exafs data analysis of some cobalt complexes

X-ray spectroscopy has assumed great significance with its increasing application in the different fields of physics like solid state physics, chemical physics, atomic physics, Plasma Physics and Astro physics etc.in present paper we obtained bond lengths of cobalt metal complexes using Levy's, LSS and Lytle methods and are compared by FEFFIT (Fitting of EXAFS by Fast Fourier Inverse Transform) method. Bond length basically known as radial distance between ligand and metal complexes. FEFFIT is computer program for calculating bond length obtained theoretical data of EXAFS.

Sealants Aim to Reduce Noise Levels in Automobiles

Silicon carbide (SiC) ceramics have superior properties in terms of wear, corrosion, oxidation, thermal shock resistance and high temperature mechanical behavior, as well. However, they can be sintered with difficulties and have poor fracture toughness, which hinder their widespread industrial applications. In this work, SiC-based ceramics mixed with 1 wt% and 3 wt% multilayer graphene (MLG), respectively, were fabricated by solid-state spark plasma sintering (SPS) at different temperatures. We report the processing of MLG/SiC composites, study their microstructure and mechanical properties and demonstrate the influence of MLG loading on the microstructure of sintered bodies. It was found that MLG improved the mechanical properties of SiC-based composites due to formation of special microstructure. Some toughening mechanism due to MLG pull-out and crack bridging of particles was also observed. Addition of 3 wt% MLG to SiC matrix increased the Vickers hardness and Young's modulus of composite, even at a sintering temperature of 1700 °C. Furthermore, the fracture toughness increased by 20% for the 1 wt% MLG-containing composite as compared to the monolithic SiC selected for reference material. We demonstrated that the evolved 4H-SiC grains, as well as the strong interactions among the grains in the porous free matrices played an important role in the mechanical properties of sintered composite ceramics.

Quantum electron-acoustic solitary waves interaction in dense electron-ion plasmas

The effects of Bohm potential on the head-on collision between two quantum electron-acoustic solitary waves (QEASWs) in two electron species quantum plasma have been investigated using the extended Poincare–Lighthill–Kuo (PLK) method. The analytical phase shifts after the head-on collision of the two QEASWs are derived. Numerically, in two cases (i.e., the dense solid state plasma and the dense astrophysical environments), the results show that the cold electron-to-hot electron number density ratio, the quantum corrections of diffraction and Fermi temperature of hot electrons have strong effects on the nature of the phase shifts and the trajectories of two QEASWs after collision.

Mechanisms of electron acceleration in the excitation of nuclear reactions in solid-state laser plasmas

Investigation of nuclear reactions in a solid-state plasma generated by modern high-intensity sources of ultrashort-wavelength laser radiation is undoubtedly of interest for establishing nuclear-reaction yields versus the intensity of laser radiation and for efficiently exciting new nuclear and photonuclear reactions—in particular, in the resonance energy region. The present article is devoted to describing, for laser plasmas, various mechanisms of electron acceleration, which triggers the acceleration of atomic ions and the excitation of subsequent nuclear reactions.

Foundations of Plasmonics

Plasma physics is a very mature field, studied extensively for well over a century. The cross-disciplinary field of plasmonics (electromagnetics of metallic nanostructures), on the other hand, with its potential for an extraordinary light control through novel class of materials and the resulting applications, has become very fashionable only recently. Inevitably, as a result of this rapid development, the deep connections with the mother discipline, the plasma physics, have sometimes been overlooked. The goal of this work is to review some of these basic connections, which are relevant, and ultimately helpful for researchers in the new field. We focus on the solid-state structured plasmas and address the issue of classical versus quantum treatments. We discuss the little known subtleties of the surface plasmons at metallic surfaces (e.g. multipole plasmons) and their consequences on plasmonics of the textured metallic films. Plasmonics of nanoparticles has been preceded by studies of plasma effects in me...

Study on Phase Composition of Long Persistence Phosphors SrAl<sub>2</sub>O<sub>4</sub>:Eu<sup>2+</sup>,Dy<sup>3+</sup>Synthesized by Combustion Synthesis Method

SrAl2O4:Eu2+,Dy3+ long persistence phosphors are synthesized by combustion method. The effects of several processing conditions such as the mole ratio of urea and metal nitrates, initiating temperature, the amounts of fluxing agent(boric acid), and raw material ratio（Sr:Al）on phase composition and subsequent on the spectroscopic properties are studied. The results show that the phase composition changed from strontium-rich phase to aluminium-rich phase with the increasing of initiating temperature, the increasing of the content of urea and boric acid, and with the decreasing of Sr:Al. The results indicate that the sample has most excellent luminescence performance is not the one which has pure single phase SrAl2O4, but the one has little impurity phase SrAl4O7. Similar phenomenon is also present when synthesized by high temperature solid-state method and microwave plasma synthesis method, so the differences among three methods are also discussed in this paper.