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Ghosh B.,University of Texas at Austin | Ghosh B.,India Institute of Technology Kanpur | Gupta A.,India Institute of Technology Kanpur
Journal of Semiconductors | Year: 2015

We have studied the WS2 armchair nanoribbon with various defects like vacancy, edge roughness, twist, turn and ripple and compared how the bandgap changes due to such defects with the bandgap of a nanoribbon with no defects. Materials like WS2 and other transition metal dichalcogenides (MX2) have a graphene like layered structure with hexagonal rings and have properties that have attracted a lot of interest. Hence it is essential to study the changes in the band structure of the nanoribbon of WS2 due to the inclusion of defects like vacancy, rough edge, wrap, ripple and twist for making any device based on WS2. © 2015 Chinese Institute of Electronics.

Saxena A.K.,India Institute of Technology Kanpur | Srivastava K.V.,India Institute of Technology Kanpur
IEEE Transactions on Antennas and Propagation | Year: 2014

A three-dimensional unconditionally stable five-step locally one-dimensional finite-difference time-domain (LOD-FDTD) method is presented. Unlike the two-step LOD-FDTD and three-step LOD-FDTD methods, the proposed method has second order temporal accuracy. Hence, it gives less numerical dispersion than the two-step LOD-FDTD and three-step LOD-FDTD methods. It also gives less numerical dispersion than the alternating direction implicit finite-difference time-domain (ADI-FDTD) method. Moreover, for every propagation angle $\theta$, it provides very small anisotropy error than the above-mentioned FDTD methods. Effects of the time step and the mesh size on the performance of the proposed method are discussed in detail. In this paper, validation of the stability and the accuracy of the proposed method is done with the help of simulation results. To further show the advantage of the proposed method, performance of the proposed method with artificial coefficients (control parameters) is also discussed in this paper. © 1963-2012 IEEE.

Ghosh B.,University of Texas at Austin | Surana N.,India Institute of Technology Kanpur | Akram M.W.,India Institute of Technology Kanpur | Tripathi B.M.M.,India Institute of Technology Kanpur
Journal of Low Power Electronics | Year: 2014

In this paper we demonstrate sub-30 nm double gate junctionless transistor (DGJLT) with channel of III-V materials. Device performances are studied by 2-D Taurus Medici device simulation. From the results we observe that III-V channel DGJLT provides better device characteristics compared to silicon and germanium channel DGJLT. The sub-30 nm device of III-V material shows high Ion /Ioff ratio, over 109 , better subthreshold slope and DIBL effect. Silicon and germanium channel DGJLT suffer from high band-to-band tunneling current in off-state, which increases off-state leakage current. In GaAs and In0.25 Ga0.75 As channel DGJLT due to high energy band gap there is no band-overlap between valence band and conduction band in horizontal direction and hence this provides lower Ioff . We also demonstrate that low doping concentration of In0.25 Ga0.75 As channel provides higher electron mobility and hence provides high Ion /Ioff ratio. Copyright © 2014 American Scientific Publishers.

Ghosh B.,University of Texas at Austin | Ghosh B.,India Institute of Technology Kanpur | Ajay A.,India Institute of Technology Kanpur | Salimath A.K.,India Institute of Technology Kanpur
Journal of Computational and Theoretical Nanoscience | Year: 2014

This paper presents the design of 2-bit Binary Divider using Quantum Dots (QDs) in Single Spin Logic (SSL) paradigm where single electron hosted in QDs act as binary logic device in which spin orientation of electrons encodes the bit information in presence of weak magnetic field. Information is transmitted from one spin to next via nearest-neighbor exchange interaction. Major advantages of SSL is lesser power dissipation, improved speed and dense structures. Copyright © 2014 American Scientific Publishers All rights reserved.

Singh R.K.,India Institute of Technology Kanpur | Chauhan N.S.,India Institute of Technology Kanpur | Mishra S.,India Institute of Technology Kanpur
2012 International Conference on Devices, Circuits and Systems, ICDCS 2012 | Year: 2012

This paper presents an average current-mode controller with a feedback clamp circuit based optimal bidirectional battery charger for automotive applications. The proposed controller forces the converter to work as a controlled current source when the battery state-of-charge (SOC) is below a predefined reference level and automatically reverts to controlled voltage source when the battery SOC exceeds the predefined reference level. The controller avoids the use of independent voltage and current loops and extra switching circuits to achieve current clamping in the proposed implementation is not based on saturation of the error amplifier, it is alway feedback controlled and the transition between constant current to constant voltage mode is smooth. The proposed implementation adapts well to Reflex™ charging technique. Experimental and simulation results are presented to verify the proposed algorithm. © 2012 IEEE.

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