Design and Analysis of High Frequency InN Tunnel Transistors

This work reports the design and analysis of an n-type tunneling field effect transistor based on InN. The tunneling current is evaluated from the fundamental principles of quantum mechanical tunneling and semiclassical carrier transport. We investigate the RF performance of the device. High transconductance of 2 mS/um and current gain cut-off frequency of around 460 GHz makes the device suitable for THz applications. A significant reduction in gate to drain capacitance is observed under relatively higher drain bias. In this regard, the avalanche breakdown phenomenon in highly doped InN junctions is analyzed quantitatively for the first time and is compared to that of Si and InAs

Impact Ionization in β−Ga2O3\beta-Ga_2O_3

A theoretical investigation of extremely high field transport in an emerging wide-bandgap material $\beta-Ga_2O_3$ is reported from first principles. The signature high-field effect explored here is impact ionization. Interaction between a valence-band electron and an excited electron is computed from the matrix elements of a screened Coulomb operator. Maximally localized Wannier functions (MLWF) are utilized in computing the impact ionization rates. A full-band Monte Carlo (FBMC) simulation is carried out incorporating the impact ionization rates, and electron-phonon scattering rates. This work brings out valuable insights on the impact ionization coefficient (IIC) of electrons in $\beta-Ga_2O_3$. The isolation of the $\Gamma$ point conduction band minimum by a significantly high energy from other satellite band pockets play a vital role in determining ionization co-efficients. IICs are calculated for electric fields ranging up to 8 MV/cm for different crystal directions. A Chynoweth fitting of the computed IICs is done to calibrate ionization models in device simulators.Comment: 13 pages, 4 figures, 1 table, in press J. Appl. Phy

Electron Mobility in Monoclinic \beta-Ga2O3 - Effect of Plasmon-phonon Coupling, Anisotropy, and Confinement

This work reports an investigation of electron transport in monoclinic \beta-Ga2O3 based on a combination of density functional perturbation theory based lattice dynamical computations, coupling calculation of lattice modes with collective plasmon oscillations and Boltzmann theory based transport calculations. The strong entanglement of the plasmon with the different longitudinal optical (LO) modes make the role LO-plasmon coupling crucial for transport. The electron density dependence of the electron mobility in \beta-Ga2O3 is studied in bulk material form and also in the form of two-dimensional electron gas. Under high electron density a bulk mobility of 182 cm2/ V.s is predicted while in 2DEG form the corresponding mobility is about 418 cm2/V.s when remote impurities are present at the interface and improves further as the remote impurity center moves away from the interface. The trend of the electron mobility shows promise for realizing high electron mobility in dopant isolated electron channels. The experimentally observed small anisotropy in mobility is traced through a transient Monte Carlo simulation. It is found that the anisotropy of the IR active phonon modes is responsible for giving rise to the anisotropy in low-field electron mobility.Comment: to be appeared in Journal of Materials Researc

Qualitative Analysis and Optimal Control Strategy of an SIR Model with Saturated Incidence and Treatment

This paper deals with an SIR model with saturated incidence rate affected by inhibitory effect and saturated treatment function. Two control functions have been used, one for vaccinating the susceptible population and other for the treatment control of infected population. We have analysed the existence and stability of equilibrium points and investigated the transcritical and backward bifurcation. The stability analysis of non-hyperbolic equilibrium point has been performed by using Centre manifold theory. The Pontryagin's maximum principle has been used to characterize the optimal control whose numerical results show the positive impact of two controls mentioned above for controlling the disease. Efficiency analysis is also done to determine the best control strategy among vaccination and treatment.Comment: 17 pages, 6 figur

Characterization of Left Ventricular Hypertrophy via Fractional Derivatives

In this paper, we have used the concepts of the fractional derivative of rough curves to characterize ECG of LVH patients and compared the results with normal ECGs. In mathematical language, an ECG is a rough curve having Q, R, S points as non-differentiable points where classical derivatives do not exist but fractional derivatives exist. We have calculated both left and right modified Riemann-Liouville fractional derivatives and their differences termed as phase transition at those non-differentiable points of V1, V2, V5, and V6 leads.Investigation shows that phase transition is higher for LVH patients than normal ones. This may be a method of determination of risk factor of LVH patients before doing Echocardiogram.Comment: 4 pages, 3 tables, submitted on 2017. arXiv admin note: text overlap with arXiv:1711.0233

Time independent fractional Schrodinger equation for generalized Mie-type potential in higher dimension framed with Jumarie type fractional derivative

In this paper we obtain approximate bound state solutions of $N$-dimensional fractional time independent Schr\"{o}dinger equation for generalised Mie-type potential, namely $V(r^{\alpha})=\frac{A}{r^{2\alpha}}+\frac{B}{r^{\alpha}}+C$. Here $\alpha(0<\alpha<1)$ acts like a fractional parameter for the space variable $r$. When $\alpha=1$ the potential converts into the original form of Mie-type of potential that is generally studied in molecular and chemical physics. The entire study is composed with Jumarie type fractional derivative approach. The solution is expressed via Mittag-Leffler function and fractionally defined confluent hypergeometric function. To ensure the validity of the present work, obtained results are verified with the previous works for different potential parameter configurations, specially for $\alpha=1$. At the end, few numerical calculations for energy eigenvalue and bound states eigenfunctions are furnished for a typical diatomic molecule.Comment: 26 page

Higher dimensional fractional time independent Schr\"{o}dinger equation via Jumarie fractional derivative with generalized pseudoharmonic potential

In this paper we obtain approximate bound state solutions of $N$-dimensional time independent fractional Schr\"{o}dinger equation for generalised pseudoharmonic potential which has the form $V(r^{\alpha})=a_1r^{2\alpha}+\frac{a_2}{r^{2\alpha}}+a_3$. Here $\alpha(0<\alpha<1)$ acts like a fractional parameter for the space variable $r$. The entire study is composed with the Jumarie type derivative and the elegance of Laplace transform. As a result we successfully able to express the approximate bound state solution in terms of Mittag-Leffler function and fractionally defined confluent hypergeometric function. Our study may be treated as a generalization of all previous works carried out on this topic when $\alpha=1$ and $N$ arbitrary. We provide numerical result of energy eigenvalues and eigenfunctions for a typical diatomic molecule for different $\alpha$ close to unity. Finally, we try to correlate our work with Cornell potential model which corresponds to $\alpha=\frac{1}{2}$ with $a_3=0$ and predict the approximate mass spectra of quarkonia.Comment: 23 pages, 8 figures. arXiv admin note: text overlap with arXiv:1708.0310

Study of memory effect in an EOQ model for completely backlogged demand during shortage

The most commonly developed inventory models are the classical economic order quantity model, is governed by the integer order differential equations. We want to come out from the traditional thought i.e. classical order inventory model where the memory phenomena are absent. Here, we want to incorporate the memory effect that is based on the fact economic agents remember the history of changes of exogenous and endogenous variables. In this paper, we have proposed and solved a fractional order EOQ model with constant demand rate where the demand is fully backlogged during shortage time. Finally, a numerical example has been illustrated for this model to show the memory dependency of the system. The numerical example clears that for the considered system the profit is maximum in long memory affected system compared to the low memory affected or memory less system

Thermoelectric Transport Coefficients in Mono-layer MoS2 and WSe2 Role of Substrate, Interface Phonons, Plasmon, and Dynamic Screening

The thermoelectric transport coefficients of electrons in two recently emerged transition metal dichalcogenides(TMD), MoS2 and WSe2, are calculated by solving Boltzmann Transport equation and coupled electrical and thermal current equations using Rode iterative technique. Scattering from localized donor impurities, acoustic deformation potential, longitudinal optical (LO) phonons, and substrate induced remote phonon modes are taken into account. Hybridization of TMD plasmon with remote phonon modes is investigated. Dynamic screening under linear polarization response is explored in TMDs sitting on a dielectric environment and the screened electron-phonon coupling matrix elements are calculated. The effect of screening and substrate induced remote phonon mediated scattering on the transport coefficients of the mentioned materials is explained. The transport coefficients are obtained for a varying range of temperature and doping density for three different types of substrates SiO2, Al2O3, and HfO2. The thermoelectric properties of interest including Seebeck coefficient, Peltier coefficient, and electronic thermal conductivity are calculated

Secure Routing and Data Transmission in Mobile Ad Hoc Networks

In this paper, we present an identity (ID) based protocol that secures AODV and TCP so that it can be used in dynamic and attack prone environments of mobile ad hoc networks. The proposed protocol protects AODV using Sequential Aggregate Signatures (SAS) based on RSA. It also generates a session key for each pair of source-destination nodes of a MANET for securing the end-to-end transmitted data. Here each node has an ID which is evaluated from its public key and the messages that are sent are authenticated with a signature/ MAC. The proposed scheme does not allow a node to change its ID throughout the network lifetime. Thus it makes the network secure against attacks that target AODV and TCP in MANET. We present performance analysis to validate our claim