First Principles Study of Metal Contacts to Monolayer Black Phosphorous

Atomically thin layered black phosphorous (BP) has recently appeared as an alternative to the transitional metal di chalcogenides for future channel material in a MOS transistor due to its lower carrier effective mass. Investigation of the electronic property of source/drain contact involving metal and two-dimensional material is essential as it impacts the transistor performance. In this paper we perform a systematic and rigorous study to evaluate the Ohmic nature of the side-contact formed by the monolayer BP (mBP) and metals (gold, titanium and palladium), which are commonly used in experiments. Employing the Density Functional Theory (DFT), we analyse the potential barrier, charge transfer and atomic orbital overlap at the metal-mBP interface in an optimized structure to understand how efficiently carriers could be injected from metal contact to the mBP channel. Our analysis shows that gold forms a Schottky contact with a higher tunnel barrier at the interface in comparison to the titanium and palladium. mBP contact with palladium is found to be purely Ohmic, where as titanium contact demonstrates an intermediate behaviour.Comment: 10 Pages 13 Figures Accepted in Journal Of Applied Physic

Prospects of Zero Schottky Barrier Height in a Graphene Inserted MoS2-Metal Interface

A low Schottky barrier height (SBH) at source/drain contact is essential for achieving high drive current in atomic layer MoS2 channel based field-effect transistors. Approaches such as choosing metals with appropriate work functions and chemical doping are employed previously to improve the carrier injection from the contact electrodes to the channel and to mitigates the SBH between the MoS2 and metal. Recent experiments demonstrate significant SBH reduction when graphene layer is inserted between metal slab (Ti and Ni) and MoS2. However, the physical or chemical origin of this phenomenon is not yet clearly understood. In this work, density functional theory (DFT) simulations are performed, employing pseudopotentials with very high basis sets to get insights of the charge transfer between metal and monolayer MoS2 through the inserted graphene layer. Our atomistic simulations on 16 different interfaces involving five different metals (Ti, Ag, Ru, Au and Pt) reveal that: (i) such a decrease in SBH is not consistent among various metals, rather an increase in SBH is observed in case of Au and Pt (ii) unlike MoS2-metal interface, the projected dispersion of MoS2 remains preserved in any MoS2-graphene-metal system with shift in the bands on the energy axis. (iii) a proper choice of metal (e.g., Ru) may exhibit ohmic nature in a graphene inserted MoS2-metal contact. These understandings would provide a direction in developing high performance transistors involving hetero atomic layers as contact electrodes.Comment: 8 pages, 6 figures Accepted in Journal of Applied Physic

Analysis of Vacancy defects in Hybrid Graphene-Boron Nitride Armchair Nanoribbon based n-MOSFET at Ballistic Limit

Here, we report the performance of vacancy affected supercell of a hybrid Graphene-Boron Nitride embedded armchair nanoribbon (a-GNR-BN) based n-MOSFET at its ballistic transport limit using Non Equilibrium Green's Function (NEGF) methodology. A supercell is made of the 3p configuration of armchair nanoribbon that is doped on the either side with 6 BN atoms and is also H-passivated. The type of vacancies studied are mono (B removal), di (B and N atom removal) and hole (removal of 6 atoms) formed all at the interface of carbon and BN atoms. Density Functional Theory (DFT) is employed to evaluate the material properties of this supercell like bandgap, effective mass and density of states (DOS). Further band gap and effective mass are utilized in self-consistent PoissonSchrodinger calculator formalized using NEGF approach. For all the vacancy defects, material properties show a decrease which is more significant for hole defects. This observation is consistent in the device characteristics as well where ON-current (ION ) and Sub Threshold Slope (SS) shows the maximum increment for hole vacancy and increase is more significant becomes when the number of defects increase.Comment: in 18th International Workshop on Computational Electronics (2015

Surface Plasmon Polaritons: Guided-wave Devices and Applications

The prospect of controlling the interaction of light with matter at nanoscale has been widely studied in recent years, and entails characterizing optical and optoelectronic devices at resolution higher than the diffraction limit. One technique that allows localization of light to sub-wavelength dimensions is through the use of surface plasmon polaritons (SPPs) wherein the interaction of light with free electrons on a metal surface can lead to a bound surface electromagnetic field that is confined to deep sub-wavelength dimensions. Studies based on SPPs merged with the field of nanotechnology have resulted in novel imaging technologies, nonlinear and quantum-optical devices and the ability to design materials with unusual electromagnetic properties with potential applications ranging from enhancing the efficiency of photovoltaic devices to detection of bio-molecules at ultra-small concentrations. Here we report the design of nanophotonic devices based on SPP waveguide structures that would act as a true counterpart to today’s electronic devices, providing orders of increase in data speeds while maintaining nanoscale dimensions. The devices are based on metal-dielectric-metal (MDM) waveguide structures composed of Ag/SiO2/Ag heterostructure that utilizes interference effect within multiple intersecting plasmonic waveguides. We have explored guided-wave devices such as L and T-bends, 4-way-splitters and 2x2-networked structures, wherein by altering the device geometry one can tune its operating frequency, and by changing the angle of incidence one can switch these devices between ON/OFF states. We plan to fabricate and experimentally characterize these devices for applications in color routing, directional filters and optical switches. We discuss preliminary design rules and constraints based on results obtained from finite-difference-time-domain simulations

India’s Transition to Global Donor: Limitations and Prospects

India has increasingly sought to expand its activities as a donor, both to reposition itself as an emerging power and to use aid as an instrument for engaging with other developing countries. This ARI looks at the current state of India’s donor programme as regards both its size and scope, identifies India’s role within the multilateral aid scenario and evaluates the challenges and prospects for further growth. This paper analyses the evolution of India’s giving in recent years. However, rather than simply describing what India gives and to whom, it primarily looks at three related questions: (1) what are the main characteristics that distinguish India’s aid?; (2) as India grows into a global donor, how is it likely to view multilateral engagement?; and (3) against the backdrop of almost certain growth in giving in the future, what are the challenges and options ahead

Relationship Between Self Efficacy and Academic Performance: an Empirical Study

This paper examines the relationship between the self-efficacy and academic performance in Graduation level students. The data were collected from 130 students (42 females and 88 males) selected from different semesters of undergraduate studies. To analyze data correlation and t-test analysis was used. The results of the study showed that there is a significant relationship between self-efficacy and academic performance of the students. In addition, we found that there is no significant relationship between self-efficacy and academic performance among students varied by age of course. From the findings, it was recommended that teachers, Counsellors, and educators should give continuous advice and develop techniques that help lower anxiety and reduce stress, to increase a student's self-efficacy

Universal Mass-Energy Equivalence Relation in Materials

A new discovery of the universal mass-energy equivalence relation applicable to materials having a bandgap, was initiated in the year 2014 and concretized in 2022-23. It is described in this short research paper. The relation is dE/E = dm/m, where E is the energy and m is the mass

Performance and Economic Analysis of Multi-Rotor Wind Turbine

Power production of a wind turbine is dependent upon its rotor size and at present wind turbines with large rotor diameter (>175 m) are available in the market. However major problems associated with such large size conventional turbines are their cost & noise pollution. Due to these reason researchers have diverted their attention towards lower sized equivalent multi-rotor wind turbines. These turbines are found to be cheaper and good performers. Keeping it in view, in this paper an effort has been made to compare the energy yield and economics of two types of wind turbines i.e. single rotor & multi rotor wind turbine. Power, energy and cost models as proposed are used to determine the annual energy yield and economics of multi-rotor turbines. Simulation results as presented in this paper justify the suitability of multi-rotor wind turbine in place of single rotor configuration. Such turbines deliver more energy yield with low installation cost in contrast to single rotor turbines

Sum of the triple divisor function and Fourier coefficients of SL(3,Z)SL(3,\mathbb{Z}) Hecke-Maass forms over quadratics

Let $\mathcal{A}(n)$ be the $(1,n)-th$ Fourier coefficients of $SL(3,\mathbb{Z})$ Hecke-Maass cusp form i.e. $\Lambda(1,n)$ or the triple divisor function $d_3(n)$, which is the number of solutions of the equation $r_1r_2r_3 = n$ with $r_1, r_2, r_3 \in \mathbb{Z}^+.$ We establish estimates for \begin{equation*} \sum_{1 \leq n_1,n_2\leq X} \mathcal{A}(Q(n_1,n_2)) \end{equation*} where $Q(x,y) \in \mathbb{Z}[x,y]$ is a symmetric positive definite quadratic form.Comment: This article is of 19 pages. Comments/Suggestions are welcom