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Kumar A.,Panjab University | Lal M.,GGD SD College | Sharma K.,Panjab University | Tripathi S.K.,Panjab University | Goyal N.,Panjab University
Indian Journal of Pure and Applied Physics | Year: 2013

The temperature dependence of dc conductivity of Se85-xTe 15Gex (x=0, 2, 6, 10, 15) chalcogenide glasses in the temperature range 273-333 K, has been reported. The dc conductivity varies exponentially with temperature for all compositions. The log σdc versus 1000/T plots are almost straight lines in whole studied temperature range indicating a singly activated phenomenon with single activation energy. Meyer-Neldel rule between pre-exponential factor and activation energy has been observed. Meyer-Neldel characteristic energy (EMN) and 00 come out to be 40.67 meV and 3.78*10-6 S cm -1, respectively.Both values lie in the range predicted by Shimakawa and Abdul-Waheb for chalcogenide glasses. Source


Kumar A.,Panjab University | Lal M.,GGD SD College | Sharma K.,Panjab University | Navdeep G.,Panjab University
Chalcogenide Letters | Year: 2013

Frequency and temperature dependent ac conductivity studies of Se85-x Te15Gex (x= 0, 2, 6, 10, 15) glasses have been reported. Results indicate that Se83 Te15 Ge2 obeys well established relation aaca< frequency exponent s is found to decrease with increase in temperature and results have been explained as the basis of correlated barrier hopping (CBH) model and numerical calculations agree well with experimental results. But a different type of behavior has been observed for Se85-x Te15Gex(x = 6, 10, 15). Distinct peaks have been observed in the plots of temperature dependence of ac conductivity for Se85-x Te15Gex (x = 10, 15). The results have been interpreted using CHB and "simple pair" model. Ge introduced localized states deep in the band gap and form simple pairs. Theoretical results obtained by using these models have been found to be in agreement with experimental results. Source


Goyal N.,Panjab University | Lal M.,GGD SD College | Kumar A.,Post Graduate Government College For Girls | Tripathi S.K.,Panjab University
AIP Conference Proceedings | Year: 2011

AgInSe2 is a material of special interest, since it is a ternary analog of CdS which has been used for a number of optoelectronic devices. Material has been studied over a wide range of frequencies (5 kHz to 1 MHz), through measurements of conductance and capacitance, at different temperatures and light intensities. The results indicate that there is an increase in capacitance (C) as well as conductance (G), when sample is exposed to light radiations at a given temperature. The switching and recovery time has been analysed in terms of time constant (τ=C/G) and found to be of the order of micro seconds. It has been further observed that switching response is faster at higher frequencies and its dependence on temperature decreases at these frequencies. It is understandable, because higher the rate of recombination of optically/thermally generated carriers, lesser should be the value of τ. © 2011 American Institute of Physics. Source


Kumar A.,Panjab University | Kumar A.,PG Government College for Girls | Lal M.,GGD SD College | Sharma K.,Panjab University | And 2 more authors.
Chalcogenide Letters | Year: 2014

Temperature and frequency dependence of dielectric constant(ε') and dielectric loss(ε") have been studied for chalcogenide glasses Se85-xTe15Gex (x= 0, 2, 6, 10, 15) by measuring capacitance and conductance in the frequency range 5 kHz to 20 kHz and temperature range 253K to 313K. Dielectric dispersion has been found to occur in this frequency and temperature range. The variation of dielectric constant and dielectric loss with temperature shows almost similar behavior for x=0, 2, 6, but dielectric constant and dielectric loss show peaks for x=10, 15. The analysis of results indicates that dielectric losses are dipolar in nature and are explained on the basis of Guintini's theory of dielectric dispersion based on two electron hopping over a potential barrier. Results show that both dielectric constant and dielectric loss decrease with increase in Germanium concentration. This is due to the decrease in defect states with increase in Germanium concentration. Source


Kumar A.,Panjab University | Kumar A.,Post Graduate Government College For Girls | Singh G.,GGD SD College | Lal M.,GGD SD College | And 2 more authors.
AIP Conference Proceedings | Year: 2011

In this paper we report the frequency and temperature dependence of ac conductivity and dielectric studies of Se85-xTe15In x glasses. The measurements have been made on Se 85-xTe15Inx (x=2, 6, 10, 15) in the frequency range 2 kHz to 50 kHz and temperature range 203 K and 313 K. Results indicate that dielectric dispersion occurs in this frequency and temperature range. The results have been explained on the basis of correlated Barrier Hopping (CBH) model. The dc conductivity increases with increase in temperature for all composition. The Log σdc versus 1000/T plots are almost straight lines in whole studied temperature range indicative of singly activated phenomena having single activation energy. © 2011 American Institute of Physics. Source

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