School Of Basic And Applied Sciences

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    First principles study of 2D ring-Te and its electrical contact with a topological Dirac semimetal
    (Royal Society of Chemistry, 2023-02-10T00:00:00) Singh, Jaspreet; Kumar, Ashok
    In recent years, researchers have manifested their interest in two-dimensional (2D) mono-elemental materials of group-VI elements because of their excellent optoelectronic, photovoltaic and thermoelectric properties. Despite the intensive recent research efforts, there is still a possibility of novel 2D allotropes of these elements due to their multivalency nature. Here, we have predicted a novel 2D allotrope of tellurium (ring-Te) using density functional theory. Its stability is confirmed by phonon and ab initio molecular dynamics simulations. Ring-Te has an indirect band gap of 0.69 eV (1.16 eV) at the PBE (HSE06) level of theories and undergoes an indirect-direct band gap transition under tensile strain. The higher carrier mobility of holes (?103 cm2 V?1 s?1), good UV-visible light absorption ability and low exciton binding (?0.35 eV) of ring-Te give rise to its potential applications in optoelectronic devices. Furthermore, the electrical contact of ring-Te with a topological Dirac semimetal (sq-Te) under the influence of an electric field shows that the Schottky barriers and contact types can undergo transition from p-type to n-type Schottky contact and then to ohmic contact at a higher electric field. Our study provides an insight into the physics of designing high-performance electrical coupled devices composed of 2D semiconductors and topological semimetals. � 2023 The Royal Society of Chemistry.
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    Mechanical, optical and thermoelectric properties of Janus BiTeCl monolayer
    (Elsevier Ltd, 2022-04-29T00:00:00) Chauhan, Poonam; Singh, Jaspreet; Kumar, Ashok
    We report mechanical, optical and thermoelectric properties of recently fabricated Janus BiTeCl monolayer using density functional and semi-classical Boltzmann transport theory. Janus BiTeCl monolayer exhibits a direct bandgap, high carrier mobility (?103 cm2V?1s?1) and high optical absorption in the UV�visible region. The mechanical behavior of the Janus BiTeCl monolayer is nearly isotropic having an ideal tensile strength ?15 GPa. The higher value of the Gruneisen parameter (?), a low value of phonon group velocity (vg), and very little phonon scattering time (?p) lead to low lattice thermal conductivity (1.46 W/mK) of Janus BiTeCl monolayer. The combined effect of thermal conductivity and electronic transport coefficients of Janus BiTeCl monolayer results in the figure of merit (ZT) in the range of 0.43�0.75 at 300�500 K. Our results suggest Janus BiTeCl monolayer be a potential candidate for optoelectronic and moderate temperature thermoelectric applications. � 2022