Department Of Physics

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Browsing Department Of Physics by Author "Ahluwalia, P.K"

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    Electronic structure and carrier mobilities of twisted graphene helix
    (Elsevier, 2020) Thakur, R; Ahluwalia, P.K; Kumar, A; Mohan, B; Sharma, R.
    Density functional theory based calculations have been carried out to investigate the effect of twisting on electronic band structures and carrier mobilities of three prototypes of armchair graphene nanoribbons (AGNRs) within the fixed boundary conditions. It is found that twisting causes a modification in the bandgap values and the overall shape of band structures. The values of longitudinal acoustic deformation potential (DP) are found to be higher than the torsional acoustic DP values. The torsional strain is also found to have a profound effect on effective mass and mobilities of given AGNRs. The hole mobility of hydrogen passivated N = 8 AGNRs is found to be comparable with the carrier mobility of intrinsic graphene. The electron mobility of N = 8 AGNRs can be further increased with fluorine passivation. The width, passivation, and extent of twisting together determine n-type or p-type behavior of AGNRs. Fluorine passivated AGNRs are predicted to be potential candidates for mechanical and high-frequency switching. Our results suggest that twisting of AGNRs can be an effective mean for tuning their band structure and carrier mobility for applications in high-speed switching devices. 2020 Elsevier B.V.
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    Strain controlled electronic and transport properties of Si-C atomic wire
    (American Institute of Physics, 2019) Thakur, R; Kumar, Ashok; Ahluwalia, P.K; Sharma, R.
    An ab-initio Density functional calculations and Non-equilibrium approach have been used to study the effect of positive strain on the equilibrium geometry, electronic structure and transmission function of Si-C bi atomic wire. In the absence of strain, Si-C bi-atomic wire is found to be semi conducting. The equilibrium electronic structure of these nanowires is shown to change drastically on applying strain. The Si-C bi-atomic wire has wide zigzag (WZ) structure GM and has a direct band gap of 0.7eV and remains direct on applying small strain up to ϵ ∼3.1%. At the strain value of ϵ ∼3.1% the band gap widen up to 1.77eV, and becomes indirect on further increasing the strain values. We observed that at the lower bias the conductance does depend on the strain applied on the wire. From density of states we have found that the strain value of ϵ ∼3.1% offers maximum band gap value up to the ∼1.55eV bias applied. At equilibrium state the transmission through Si bands is observed slightly more, and indicates the holes tunneling through device. Application of strain provides channels for electrons tunneling. © 2019 Author(s).
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    Strain tunable Schottky barriers and tunneling characteristics of borophene/MX2 van der Waals heterostructures
    (Elsevier, 2020) Katoch, N; Kumar, A; Sharma, R; Ahluwalia, P.K; Kumar, J.
    Based on first-principle calculations, we report the strain induced changes in electronic properties and their influence on current-voltage (I?V) characteristics of the borophene (?12)/MX2 (M = Mo, W and X = S, Se) vdW heterostructures. The results reveal that the intrinsic electronic nature of borophene and MX2 is retained because of weak van der Waals interactions. However, p-type Schottky contacts are formed at the interface of the heterostructures. Application of the in-plane tensile and compression strains is effective in tuning the Schottky contacts and controlling the SBHs. Also, at the vertical pressure values of 5.46 and 5.25 GPa for ?12/MoS2 and ?12/WS2 respectively, Schottky contact changes from p-type to n-type. The I?V characteristics exhibit an ohmic behavior at low bias ±0.1 v and noticeable NDR on changing positive (negative) biases. Such strain tunable Schottky barriers may be influential in ?12/MX2 based high-performance nano- and optoelectronic devices. - 2020 Elsevier B.V.
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    Tuning of Schottky barriers in borophene/MoS2 van der Waals heterostructure by external electric field
    (American Institute of Physics, 2019) Katoch, N; Thakur, R; Kumar, Ashok; Ahluwalia, P.K; Kumar, J.
    A first principle study of structural properties, band bending and tuning of schottky barrier height (SBH) of borophene/MoS2 Van der Waals heterostructure has been carried out within the framework of density functional theory (DFT). Studied binding energy shows that the interaction between borophene and MoS2 is weak. Consequently, both borophene and MoS2 are preserving their electronic nature in heterostructure. We have calculated the band bending 0.15 eV for borophene and -0.52 eV for MoS2 in borophene/MoS2 heterostructure which shows that the metal-semiconductor contact is in between p-type borophene and n-type MoS2. On the application of external electric field, tuning of schottky barriers has been achieved and metal-semiconductor contact gets transformed into ohmic contact which is important for the fast performance of electronic devices. © 2019 Author(s).