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Pal R.K.,Uttar Pradesh Technical University | Agnihotri A.K.,Bnd College | Kumar A.,Uttar Pradesh Technical University
Chalcogenide Letters | Year: 2010

Transient Photoconductivity measurements have been made in vacuum evaporated thin films of Se30Te70-xZnx at different intensities, temperatures and illumination times. The films exhibit long-lived residual photoconductivity, called persistent photoconductivity, with an extremely slow decay rate. The persistent photoconductivity (PPC) increases with an increase in intensity and illumination time. However, this quantity decreases with increase in temperature. These results indicate that the decay of photoconductivity is not only governed by the carrier trapped in the intrinsic defects but also gets affected by the light induced defect creation through structural changes. Source


Yadav S.,Uttar Pradesh Technical University | Pal R.K.,Bnd College | Sharma S.K.,Uttar Pradesh Technical University | Dwivedi P.K.,DST Unit on Nano science | Kumar A.,Uttar Pradesh Technical University
Vacuum | Year: 2011

The present paper reports on thermally stimulated current measurements in a-Se99.5Bi0.5 thin films at different heating rates (β1 = 2.17 K/min, β2 = 2.85 K/min, β3 = 5.00 K/min). A well-defined TSC peak at a particular temperature has been observed which shifts toward higher temperatures (T 1 = 362 K, T2 = 372 K, T3 = 392 K) on increasing the heating rate (β). Using three different approaches the trap depth has been calculated giving good agreement with each other. The average value of trap depth is 0.29 eV. Trap density has also been calculated to be 6.62 × 1019 cm-3. © 2010 Elsevier Ltd. All rights reserved. Source


Singh S.P.,Government Post Graduate College | Janma R.,Bnd College | Jatan R.,Bnd College | Singh V.,Banaras Hindu University | Singh B.D.,Government Post Graduate College
Journal of Infrared, Millimeter, and Terahertz Waves | Year: 2010

Abstracts: In this paper, we present an analytical study of the modal characteristic, cutoff conditions and dispersion curves of a circular doubly clad optical waveguides with plasma in inner cladding region. The proposed waveguide has three parts namely core with higher index dielectric material, inner cladding with plasma and outer cladding with lower index dielectric material. Using boundary matching method under weak guidance condition, the modal characteristic equation of proposed waveguide has been obtained. Analysis shows that the introduction of plasma in waveguide provides additional parameters for controlling the propagation property. © 2010 Springer Science+Business Media, LLC. Source


Janma R.,Bnd College | Jatan R.,Bnd College | Singh S.P.,Government Post Graduate College | Dwivedi P.,Vssd College | And 2 more authors.
Optik | Year: 2011

The modal dispersion characteristics of EM waves in a new unconventional plasma loaded doubly clad waveguide having a shape of the lemniscates of Bernoulli-type core cross-section have been studied analytically. The proposed waveguide has three parts namely the core with slighter high index, the inner cladding with plasma and the outer cladding with air. Now using the necessary orthogonal coordinates for the proposed structure and imposing the boundary conditions under the weak guidance condition, the modal characteristics equation has been obtained considering variations in plasma width and plasma frequency, the dispersion curves and cutoff frequencies have been obtained and presented in this paper. It is noted that as the width of plasma layer increases, the cutoff frequency also increases considerably in all considered cases. This shows that using plasma width as a new parameter we can control any particular mode on our wish. © 2010 Published by Elsevier GmbH. Source

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