Unusual effect of tellurium doping on the electrical-properties of bulk amorphous selenium

Abstract is not available.

Carrier mobility in polycrystalline semiconductors

This letter presents a modified version of the grain boundary barrier model for polycrystalline semiconductors which takes into account the carrier transport in the bulk of the grain and the dynamic process of capture and release of free carriers by the grain boundary traps.

Pressure transitions and electron transport behaviour of crystalline Se-Te alloys

Pressure transitions of Se-Te alloys have been studied over the entire range of compositions. Conductivities have also been measured as a function of temperature and alloy composition. Transition pressures, activation barriers and isothermal conductivities exhibit distinct changes of slope in their variation as a function of composition at about 8 at % of Te. Transition pressures change slope at not, vert, similar 35% Te also. An attempt has been made to explain these observations on the basis of the size effect of Te which, in turn, affects the electron energy dispersions in the band structure.

Long Wavelength Peristaltic Transport of Non-Newton Fluids

Solutions are obtained for the stream function and the pressure field for the flow of non-Newtonian fluids in a tube by long peristaltic waves of arbitrary shape. The axial velocity profiles and stress distributions on the wall are discussed for particular waves of some practical interest. The effect of non- Newtonian character of the fluid is examined.

Electrical Discharge Resistant Characteristics of Epoxy Nanocomposites

This paper reports the electrical discharge resistant characteristics of epoxy nanocomposite systems with SiO2 and Al2O3 nano-fillers. A comparative study is performed between unfilled epoxy systems, nanoparticle filled epoxy systems and a bimodal system containing both micrometer and nanometer sized fillers of the same material. The samples are exposed to surface discharges and the levels of surface degradation are analyzed through SEM and surface roughness measurements. Significant variations were observed in the electrical discharge resistant characteristics between the different composite systems and it is seen that the introduction of nano-fillers to epoxy is advantageous in improving the electrical discharge resistance of epoxy.

Effect of pressure on the electrical resistivity of indium sulphide

Indium sulphide (INS) is a III-VI compound semiconductor and crystallizes in the orthorhombic structure with a space group D~(Pmnn). The lattice parameters at room temperature and atmospheric pressure are: a = 3.944 A, b = 4.447 A and c= 10.648#, [1, 2]. The crystal structure comprises an ethane-like SalnlnS3 atomic arrangement;the SalnInS3 groups are mutually linked by sharing S corners and form a three-dimensional network.

Co-induction of sucrose transport and invertase activities in a thermophilic fungus,Thermomyces lanuginosus

The incorporation of sucrose into the thermophilic fungus,Thermomyces lanuginosus, occurred only in mycelia previously exposed to sucrose or raffinose. Sucrose uptake and invertase were inducible. Both activities appeared in sucrose-induced mycelia at about the same time. Both activities declined almost simultaneously following the exhaustion of sucrose in the medium. The sucrose-induced uptake system was specific for \beta -fructofuranosides as revealed by competition with various sugars. The induction of sucrose uptake system was blocked by cycloheximide, showing that it was dependent on new protein synthesis. Transport of sucrose did not seem to be dependent on ATP. Rather, uptake of this sugar seemed to be driven by a proton gradient across the plasma membrane. The uptake system showed Michaelis-Menten kinetics.

Electrical, structural and magnetic properties of polyaniline/pTSA-TiO2 nanocomposites

Polyaniline (PANI)/para-toluene sulfonic acid (pTSA) and PANI/pTSA-TiO2 composites were prepared using chemical method and characterized by infrared spectroscopy (IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM). The electrical conductivity and magnetic properties were also measured. In corroboration with XRD, the micrographs of SEM indicated the homogeneous dispersion of TiO nanoparticles in bulk PANI/pTSA matrix. Conductivity of the PANI/pTSA-TiO2 was higher than the PAN[/pTSA, and the maximum conductivity obtained was 9.48 (S/cm) at 5 wt% of TiO2. Using SQUID magnetometer, it was found that PANI/pTSA was either paramagnetic or weakly ferromagnetic from 300 K down to 5 K with H-C approximate to 30 Oe and M-r approximate to 0.015 emu/g. On the other hand,PANI/pTSA-TiO2 was diamagnetic from 300 K down to about 50 K and below which it was weakly ferromagnetic. Furthermore, a nearly temperature-independent magnetization was observed in both the cases down to 50 K and below which the magnetization increased rapidly (a Curie like susceptibility was observed). The Pauli susceptibility (chi(pauli)) was calculated to be about 4.8 X 10(-5) and 1.6 x 10(-5)emug(-1) Oe(-1) K for PANI/pTSA and PANI/pTSA-TiO2, respectively.

Effect of inter-edge Coulomb interactions on transport through a point contact in nu=5/2 quantum Hall state

We study transport across a point contact separating two line junctions in a nu = 5/2 quantum Hall system. We analyze the effect of inter-edge Coulomb interactions between the chiral bosonic edge modes of the half-filled Landau level (assuming a Pfaffian wave function for the half-filled state) and of the two fully filled Landau levels. In the presence of inter-edge Coulomb interactions between all the six edges participating in the line junction, we show that the stable fixed point corresponds to a point contact that is neither fully opaque nor fully transparent. Remarkably, this fixed point represents a situation where the half-filled level is fully transmitting, while the two filled levels are completely backscattered; hence the fixed point Hall conductance is given by G(H) = 1/2e(2)/h. We predict the non-universal temperature power laws by which the system approaches the stable fixed point from the two unstable fixed points corresponding to the fully connected case (G(H) = 5/2e(2)/h) and the fully disconnected case (G(H) = 0).

Pressure and temperature dependence of the electrical resistivity of bulk Al23 Te77 glass

Electrical resistivity of bulk amorphous Al23T77 samples has been studied as a function of pressure (up to 80 kbar) and temperature (down to 77 K). At atmospheric pressure the temperature dependence of resistivity obeys the relation = π0 exp(δE/RT) with two activation energies. In the temperature range 300 K T > 234 K the activation energy is 0.58 eV and for 234 >T 185 K the value is δE = 0.30 ev. The activation energy has been measured as a function of pressure. The electrical resistivity decreases exponentially with the increase of pressure and at 70 kbar pressure the electrical behaviour of the sample shows a metallic nature with a positive temperature coefficient. The high pressure phase of the sample is found to be a crystalline hexagonal phase.

Weak rectifying behaviour of p-SnS/n-ITO heterojunctions

This work explores the electrical properties of p-SnS/n-ITO heterojunction at different temperatures. The p-type SnS film was deposited on n-type ITO substrate using the thermal evaporation technique and its junction properties were studied using two probe method. The as-grown p-n junction exhibited weak rectifying behaviour with a low Saturation current of the order of similar to 10(-6) A. While increasing temperature, the saturation current of the junction is increased and however, its series resistance decreased. At all temperatures the junction exhibited three types of transport mechanisms depending on applied bias-voltage. At lower voltages the junction showed nearly ideal diode characteristics. The junction behaviour with respect to bias-voltage and temperature is discussed with the help of existing theories and energy band diagram.

Swarm intelligence-based solver for parameter estimation of laboratory through-diffusion transport of contaminants

Theoretical approaches are of fundamental importance to predict the potential impact of waste disposal facilities on ground water contamination. Appropriate design parameters are generally estimated be fitting theoretical models to data gathered from field monitoring or laboratory experiments. Transient through-diffusion tests are generally conducted in the laboratory to estimate the mass transport parameters of the proposed barrier material. Thes parameters are usually estimated either by approximate eye-fitting calibration or by combining the solution of the direct problem with any available gradient-based techniques. In this work, an automated, gradient-free solver is developed to estimate the mass transport parameters of a transient through-diffusion model. The proposed inverse model uses a particle swarm optimization (PSO) algorithm that is based on the social behavior of animals searching for food sources. The finite difference numerical solution of the forward model is integrated with the PSO algorithm to solve the inverse problem of parameter estimation. The working principle of the new solver is demonstrated and mass transport parameters are estimated from laboratory through-diffusion experimental data. An inverse model based on the standard gradient-based technique is formulated to compare with the proposed solver. A detailed comparative study is carried out between conventional methods and the proposed solver. The present automated technique is found to be very efficient and robust. The mass transport parameters are obtained with great precision.