Bhupesh Bishnoi

Ripple carry adder using five input majority gates

Quantum dot Cellular Automata (QCA) is a transistor less computational model which is expected to provide high density nanotechnology implementations of various CMOS circuits. QCA has been constrained by the number of basic gates available. This paper aims at using five input majority gate to implement two adder circuits achieving implementation in lesser number of cells and higher density.

Temperature effect on hetero structure junctionless tunnel FET

For the first time, we investigate the temperature effect on AlGaAs/Si based hetero-structure junctionless double gate tunnel field effect transistor. Since junctionless tunnel FET is an alternative substitute device for ultra scaled deep-submicron CMOS technology, having very good device characteristics such as an improved subthreshold slope (< 60 mV/decade at 300 K) and very small static leakage currents. The improved subthreshold slope and static leakage current confirms that it will be helpful for the development of future low power switching circuits. The 2-D computer based simulation results show that OFF-state leakage current is almost temperature independent for the proposed device structure.

Effects of defects on the electronic properties of WTe2 armchair nanoribbons

We have investigated the electronic properties of WTe2 armchair nanoribbons with defects. WTe2 nanoribbons can be categorized depending on the edge structure in two types: armchair and zigzag. WTe2 in its bulk form has an indirect band gap but nanoribbons and nanosheets of WTe2 have direct band gaps. Interestingly, the zigzag nanoribbon is metallic while the armchair nanoribbons are semiconducting. Thus they can find applications in device fabrication. Therefore, it is very important to study the effect of defects on the electronic properties of the armchair nanoribbons as these defects can impair the device properties and characteristics. We have considered defects such as: vacancy, rough edge, wrap, ripple and twist in this work. We report the band gap variation with these defects. We have also studied the change in band gap and total energy with varying degrees of wrap, ripple and twist.

Effect of tensile strain on the negative differential resistance in the WTe2 armchair nanoribbon

In this work, we have studied the charge transport characteristics of WTe2 armchair nanoribbon and analyzed the variation in results by applying tensile strain to the nanoribbon. Tungsten ditelluride (WTe2) is a member of the transition metal dichalcogenides family. WTe2 is orthorhombic in structure with lattice parameters a = 0.6282 nm, b = 0.3496 nm, c = 1.407 nm. We have simulated the model using first-principle density functional tight binding theory and the non-equilibrium Greens function method to study the effect of strain on the transport characteristics. The obtained results are compared with that of the perfectly relaxed nanoribbon. We have applied uniaxial ( xx) and biaxial ( xx = yy) tensile strain to the nanoribbon. We present the ID-VDS characteristics, transmission spectrum and conductance for different cases. Negative differential resistance (NDR) is observed in all the cases along with a change in peak-to-valley current ratio (PVCR) and negative differential resistance region (NDRR).

Magnon scattering in single and bilayer graphene intercalates

Semi-classical Monte Carlo simulation is used to determine the effect of magnetic substance as intercalated layer in single layer and bilayer graphene intercalates on spin relaxation length. Spin relaxation lengths are studied with spin density matrix calculation under the effect of one magnon scattering mechanisms. Spin relaxation lengths are simulated and made comparisons by including magnon scattering with phonon scattering. The results are simulated with varying temperatures below Curie temperature.