Metal-semiconductor field-effect transistors fabricated using DVT grown n-MoSe2 crystals with Cu-Schottky gates

Metal-semiconductor field-effect transistors (MESFETs) based on DVT grown MoSe2 crystals and Cu Schottky gate have been fabricated and studied. When Schottky gate voltage (Vgs) changes from 0 to 10 V, the source-drain current (Ids) increases exponentially with Vgs and the conductance shows a drastic increase with positive Vgs. The fabricated n-MoSe2 MESFET have a saturated current level of about 100 mA and maximum transconductance of about 53 mA/V. Their results suggest a way of fabricating MESFETs from layered metal dichalcogenide semiconducting materials. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2207

Chemical, Structural and Optical Properties of ē-Beam Evaporated Tungsten Diselenide Polycrystalline Thin Film

Polycrystalline thin films of tungsten dieseline were prepared by using rarely reported technique of electron beam evaporation for transition metal dichalcogenides. High purity (99.999 %) reacted compound was used as starting material for the preparation of WSe2 thin films. Various parameters and conditions are outlined which were used for deposition of thin films. The prepared films were characterized using EDAX spectrum, X-ray diffraction, Electron diffraction, Scanning electron microscopy and optical absorption spectroscopy methods. The as grown films were found to be partially transparent, uniform and well adherent. Uniformity was confirmed by SEM. WSe2 film was found in stoichiometric proportion. XRD pattern as well as TEM images revealed the fact that the deposited films are polycrystalline in nature having hexagonal structure. From the study of optical absorption spectra it is found that the prepared films show direct allowed transition with optical band gap of 1.89 eV. The results are in good agreement with the earlier published data of WSe2 thin films deposited by different techniques. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2959

MoSe2 / polyaniline solar cells

Solar cells have been investigated since long for harnessing the solar energy. During this decade, a new direction has come up where in the polymers have been used in the fabrication of solar cells. Polyaniline is one of the polymers which has shown potential for its applications in heterostructure solar cells. This material is being used along with the semiconductors like InSe, TiO2, Si etc. to form the photosensitive interface. In this direction, we report our inv estigations on the use of Molybdenum diselenide (MoSe2) as photosensitive semiconducting material in MoSe2 / polyaniline solar cells. In this paper, the preparation of MoSe2 / polyaniline solar cells has been reported. Also, the photovoltage ® photocurrent characteristics of this structure have been discussed in detail in this paper. The variation of different parameters of MoSe2 / polyaniline solar cells (like open circuit voltage, short circuit current, photoconversion efficiency and fill factor) with the intensity of incident illuminations has been reported in this paper. In present case, the photocurrent density was found to be around 250 μA/cm2 with the photovoltage around 8.5 mV (which is low) the photoconversion efficiency was found to be around 0.7 % along with the fill factor around 0.33. The efforts have been made to explain the low values of the photoconversion efficiency. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2209

Temperature dependent I-V characteristics of Ag/p-Sn0.2Se0.8 thin film Schottky barrier diode

Ag/p-Sn0.2Se0.8 Schottky barrier diodes have been fabricated and characterized by the current-voltage (I-V) technique as a function of temperature in the range of 303 K to 403 K. The forward bias characteristics have been analyzed on the basis of thermionic emission (TE) theory and the characteristic parameters of Schottky barrier diode such as barrier height, ideality factor and series resistance have been determined. The conventional Richardson plot was drawn and the value of Richardson constant was determined using the intersection of Ln(I0/T2) vs 1000/T. It is found to be around 15 Acm – 2K – 2 which is closer to the reported value for SnSe. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2212

Influence of Supercurrents on Low-Temperature Thermopower in Mesoscopic N/S Structures

The thermopower of mesoscopic normal metal/superconductor structures has been measured at low temperatures. Effect of supercurrent present in normal part of the structure was studied in two cases: when it was created by applied external magnetic field and when it was applied directly using extra superconducting electrodes. Temperature and magnetic field dependencies of thermopower are compared to the numerical simulations based on the quasiclassical theory of the superconducting proximity effect.Comment: 21 pages, 12 figures. To be published in the proceedings of the ULTI conference organized in Lammi, Finland (2006

Friedmann-like equations for High Energy Area of Universe

In this paper, evolution of the high energy area of universe, through the scenario of 5 dimensional (5D) universe, has been studied. For this purpose, we solve Einstein equations for 5D metric and 5D perfect fuid to derive Friedmann-like equations. Then we obtain the evolution of scale factor and energy density with respect to both space-like and time-like extra dimensions. We obtain the novel equations for the space-like extra dimension and show that the matter with zero pressure cannot exist in the bulk. Also, for dark energy fuid and vacuum fluid, we have both accelerated expansion and contraction in the bulk.Comment: 9 pages, Accepted to publication in IJTP 26 June 2012. arXiv admin note: substantial text overlap with arXiv:1202.497

Thermoelectric effects in superconducting proximity structures

Attaching a superconductor in good contact with a normal metal makes rise to a proximity effect where the superconducting correlations leak into the normal metal. An additional contact close to the first one makes it possible to carry a supercurrent through the metal. Forcing this supercurrent flow along with an additional quasiparticle current from one or many normal-metal reservoirs makes rise to many interesting effects. The supercurrent can be used to tune the local energy distribution function of the electrons. This mechanism also leads to finite thermoelectric effects even in the presence of electron-hole symmetry. Here we review these effects and discuss to which extent the existing observations of thermoelectric effects in metallic samples can be explained through the use of the dirty-limit quasiclassical theory.Comment: 14 pages, 10 figures. 374th WE-Heraus seminar: Spin physics of superconducting heterostructures, Bad Honnef, 200

Measurement of the Ds lifetime

We report precise measurement of the Ds meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c Sigma-, pi- and p beams. The measurement has been done using 918 reconstructed Ds. The lifetime of the Ds is measured to be 472.5 +- 17.2 +- 6.6 fs, using K*(892)0K+- and phi pi+- decay modes. The lifetime ratio of Ds to D0 is 1.145+-0.049.Comment: 5 pages, 2 figures submitted to Phys. Lett.

Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical method to determine significance of observation. Submitted to PL