Browsing by Author "V.K. Tomar"

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A brief review of amorphous semiconductors
(Elsevier Ltd, 2023) Shobhit Saraswat; V.K. Tomar; V.K. Deolia; N. Mehta
One ongoing major problem in solid-state physics is to understand the effect of disorder on the properties of materials. Disordered materials often display novel properties as compared to their crystalline counterpart. Many of these properties are useful for various technological applications, such as window glass, solar cells, etc. Disordered or amorphous materials are desirable for application because they are cheaper to manufacture and, therefore, their study is highly significant and it establishes the necessities of academic and industrial applications. It is also very challenging since many of these existing experimental techniques and theoretical formalisms which have been developed for crystals are either inapplicable or require modification. The present paper reports an overview the amorphous semiconductors. The paper starts with the historical growth of amorphous semiconductors and covers all basic perspectives of Chalcogenide glasses (ChGs) that are a renowned example of amorphous semiconductors. © 2023
Estimation of density of charged defect states in some glasses of SeTeSnPb system using low-temperature d.c. conductivity measurements
(Springer, 2021) Shobhit Saraswat; V.K. Tomar; V.K. Deolia; A. Sharma; A. Dahshan; N. Mehta
The charged defect states in chalcogenide glasses (ChGs) are responsible for the hopping conduction. The estimation of the density of defect states (i.e., DDS) is a crucial task when we choose a specific ChG as electronic material for its utilization in industry-level applications. ChGs are also famous as electronic materials since they possess exceptional electrical properties (e.g., thermally governed ac/dc conduction, resistive switching, dielectric dispersion). The present study reports the results of the low-temperature dc conductivity measurements in some multicomponent glasses of SeTeSnPb. For this, the dc conductivity has been measured in the low-temperature range. The detailed analysis of obtained data indicates that the dc conductivity obeys Mott’s T−1/4 law in this region. The DDS has been determined and its composition dependence is also discussed. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Study of defect state chemistry of chalcogens elements (Se/Te) in binary Se100-xTex glassy system using lowtemperature d.c. conductivity measurements
(National Institute of Optoelectronics, 2020) Shobhit Saraswat; V.K. Tomar; N. Chandel; N. Mehta
The density of defect states (DDS) has always been a subject of curiosity in electronic materials as the knowledge of this parameter is a key parameter for determining the applications of these materials. Chalcogenide glasses are well known as electronic materials because of their excellent electrical properties (e.g., resistive switching, thermally activated a.c. and d.c. conduction, dielectric relaxation, etc). In the present paper, the d.c. conductivity has been measured for chalcogens elements Se and Te based binary glasses in the low-temperature region to apply the Mott’s theory of electronic conduction. The conduction mechanism in this region follows the Mott’s temperature dependence. The further investigations provide the estimation of the density of defect states (DDS) in Se100-xTex alloys. The value of DDS is decreased with the increase in Te concentration. We have observed a correlation between the DDS and the electronegativity of the chalcogens elements Se and Te. The compositional dependence of the hopping parameters indicates that the condition becomes easier for the variable range hoping with the rise in the Te concentration. © 2020, National Institute of Optoelectronics. All rights reserved.
Study of Metal-Induced Effects of Cd, Sb and Zn on d.c./a.c. Conduction and Photoconduction in Binary Se70Te30 Glass
(Springer, 2020) Shobhit Saraswat; V.K. Tomar; N. Mehta; A. Dahshan
This paper reports the temperature dependence of d.c. and a.c. conductivity in the glassy alloys of Se70Te30 and Se70Te28M2 (M = Cd, Sb, Zn). The role of the Cd, Sb, Zn elements as foreign atoms has been examined on the d.c./a.c. conduction and photoconduction in binary Se70Te30 glass. These multi-component chalcogenide glasses have been prepared by conventional, cost-effective and well-known melt-quench technique. Thermally activated a.c. conduction shows the presence of the compensation effect that is confirmed by the Meyer–Neldel relation between the associated activation energy and the pre-factor of a.c. conductivity. The metal-induced effects of Cd, Sb, Zn on the photosensitivity of parent glass are also discussed. © 2019, The Minerals, Metals & Materials Society.