School Of Basic And Applied Sciences

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Author: search.filters.author.Kumar, ASubject: search.filters.subject.density functional theory

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    Pressure and electric field tuning of Schottky contacts in PdSe2/ZT-MoSe2 van der Waals heterostructure
    (Institute of Physics Publishing, 2020) Jakhar, M; Singh, J; Kumar, A; Tankeshwar, K.
    A two-dimensional van der Waals (vdW) heterostructure (PdSe2/ZT-MoSe2) has been investigated through vdW corrected density functional theory. ZT-MoSe2 acts as a Dirac material with an anisotropic Dirac cone and variable Fermi velocity (0.52-1.91 105 ms-1). The intrinsic Schottky barrier height can be effectively tuned by applying external pressure and an electric field to the heterostructure. The p-type Schottky barrier transforms into a p-type ohmic contact at pressure P ? 16 GPa. A positive electric field induces p-type ohmic contact while a negative electric field results in the transition from p-type Schottky contact to n-type Schottky contact, and finally to n-type ohmic contact at the higher values of the field. Moreover, the external positive (negative) electric field induces n-type (p-type) doping of ZT-MoSe2 in the heterostructure and remarkably controls the charge carrier concentration. Our results demonstrate that controlling the external pressure and electric field in a PdSe2/ZT-MoSe2 heterostructure can result in an unprecedented opportunity for the design of high-performance nanodevices. � 2020 IOP Publishing Ltd.
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    Novel phosphorus-based 2D allotropes with ultra-high mobility
    (Institute of Physics Publishing, 2020) Kaur, S; Kumar, A; Srivastava, S; Tankeshwar, K; Pandey, R.
    Electronic structure calculations based on density functional theory were performed to investigate structural, mechanical, and electronic properties of phosphorene-based large honeycomb dumbbell (LHD) hybrid structures and a new phosphorene allotrope, referred to as ??-P. The LHD hybrids (i.e., X6P4; X being C or Si or Ge or Sn) and ??-P have significantly higher bandgaps than the corresponding pristine LHD structures, except the case of C6P4, which is metallic. ??-P is found to be a highly flexible p-type material which shows strain-engineered photocatalytic activity in a highly alkaline medium. The carrier mobility of the considered systems is as high as 105 cm2 V-1 s-1 (specifically the electron mobility of LHD structures). The calculated STM images display the surface morphologies of the LHD hybrids and ??-P. The predicted phosphorus-based 2D structures with novel electronic properties may be candidate materials for nanoscale devices. - 2020 IOP Publishing Ltd.