• S K Tripathi

      Articles written in Pramana – Journal of Physics

    • Electrical properties of a-GexSe100-x

      Abdolali Zolanvari Navdeep Goyal S K Tripathi

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      In general, the conductivity in chalcogenide glasses at higher temperatures is dominated by band conduction (DC conduction). But, at lower temperatures, hopping conduction dominates over band conduction. A study at lower temperature can, eventually, provide useful information about the conduction mechanism and the defect states in the material. Therefore, the study of electrical properties of GexSe100-x in the lower temperature region (room temperature) is interesting. Temperature and frequency dependence of GexSe100-x (x = 15, 20 and 25) have been studied over different range of temperatures and frequencies. An agreement between experimental and theoretical results suggested that the behaviour of germanium selenium system (GexSe100-x) have been successfully explained by correlated barrier hopping (CBH) model.

    • Meyer–Neldel DC conduction in chalcogenide glasses

      S PraKash Kulbir Kaur Navdeep Goyal S K Tripathi

      More Details Abstract Fulltext PDF

      Meyer–Neldel (MN) formula for DC conductivity ($\sigma_{\text{DC}}$) of chalcogenide glasses is obtained using extended pair model and random free energy barriers. The integral equations for DC hopping conductivity and external conductance are solved by iterative procedure. It is found that MN energy ($\Delta E_{\text{MN}}$) originates from temperature-induced configurational and electronic disorders. Single polaron-correlated barrier hopping model is used to calculate $\sigma_{\text{DC}}$ and the experimental data of Se, As2S3, As2Se3 and As2Te3 are explained. The variation of attempt frequency $\upsilon_0$ and $\Delta E_{\text{MN}}$ with parameter $(r/a)$, where 𝑟 is the intersite separation and 𝑎 is the radius of localized states, is also studied. It is found that $\upsilon_0$ and $\Delta E_{\text{MN}}$ decrease with increase of $(r/a)$, and $\Delta E_{\text{MN}}$ may not be present for low density of defects.

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