Browsing by Author "Ahluwalia P.K."

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Electron transport and thermoelectric performance of defected monolayer MoS2
(Elsevier B.V., 2019) Sharma M.; Kumar A.; Ahluwalia P.K.
Electronic and thermoelectric properties of a two-dimensional MoS2 monolayer containing atomic defects are investigated using density functional theory. All the atomic defects have been found to exhibit endothermic nature. Electronic structure of MoS2 shows tuneability of band gap with the atomic defects. The MoS2 vacancy in pristine monolayer makes it magnetic and narrow band gap semiconductor. The spin-polarized character of the monolayer with defects is clearly captured by the tunneling current calculated in the STM-like setup. A relatively low thermal conductivity has been observed in monolayers with defects as compared to pristine form resulting in enhanced room temperature figure of merit as high as 6.24 and 1.30 respectively. The results presented open up a new window for the use of monolayer MoS2 in electronic devices, thermal management and thermoelectric devices.
Superior Mechanical and Electronic Properties of Novel 2D Allotropes of As and Sb Monolayers
(American Chemical Society, 2019) Jamdagni P.; Thakur A.; Kumar A.; Ahluwalia P.K.; Pandey R.
Novel monolayer allotropes of As and Sb monolayers are predicted to be energetically and dynamically stable by calculations based on density functional theory. Remarkably, these monolayers possess superior mechanical flexibility and can withstand tensile strain as large as 58% in the armchair direction and 24% in the zigzag direction, which are higher than the strain limits of 2D materials such as graphene, MoS2, and phosphorene. The predicted mechanical flexibility is mainly due to the highly puckered nature of these monolayer structures. Tensile strain along the armchair direction expands the puckering of the structure by increasing the dihedral angle without a significant increase in the bond lengths. Moreover, the mechanical properties are found to be highly anisotropic: Young's modulus in the armchair direction is 3 times less than that in the zigzag direction. Furthermore, we show that these monolayer allotropes undergo semiconductor-to-metal transition on application of uniaxial strains and a transverse electric field. The calculated results show the possibility of wide-range tuning of the band gap of these monolayers while keeping their direct gap behavior intact, which can be useful in optoelectronic applications including light-emitting diodes and solar cells.