Dependence of DC characteristics of CNT MOSFETs on bandstructure models

http://www.gianlucafiori.org/articles/CNTieeenano.pd

Simulation of INSB Devices using Drift-Diffusion Equations

Silicon technology has for several decades followed Moore\u27s law. Reduction of feature dimensions has resulted in constant increase in device density which has enabled increased functionality. Simultaneously, performance, such as circuit speed, has been improving. Recently, this trend is in jeopardy due to, for example, unsustainable increase in the processor power dissipation. In order to continue development trends, as outlined in ITRS roadmap, new approaches seem to be required once feature size reaches 10 - 20 nm range. This research focuses on using 111-V compounds, specifically indiumantimonide (lnSb), to supplement silicon CMOS technology. Due to its low bandgap and high mobility, lnSb shows promise as a material for extremely high frequency active devices operating at very low voltages. In this research electrical properties of lnSb material are characterized and modeled with special emphasis on recombination-generation mechanisms. Device simulators based on drift-diffusion approach - DESSIS and nanoMOS - are modified for lnSb MOSFET design and analysis. To assess the quality of lnSb MOSFET designs several figures of merit are utilized: lon/loff ratio, 1-V characteristics, threshold voltage, drain induced barrier lowering (DIBL) and unity current gain frequency for different configurations and gate lengths. It is shown that significant performance improvement can be achieved in lnSb MOSFETs through proper scaling. For example, extrapolated cutoff frequencies reach into THz range. Semi-empirical scaling rules that remedy short channel effects are proposed. Finally, quantum mechanical (QM) effects in lnSb MOSFET and their effect on device performance are examined using nanoMOS device simulation program. It is found that nonparabolicity has to be properly modeled and that QM effects have a large effect on threshold voltage and transconductance and should be included when analyzing and designing deca-nanometer size lnSb MOSFETs

A Hydrodynamic Model for Silicon Nanowires Based on the Maximum Entropy Principle

Silicon nanowires (SiNW) are quasi-one-dimensional structures in which the electrons are spatially confined in two directions, and they are free to move along the axis of the wire. The spatial confinement is governed by the Schrodinger–Poisson system, which must be coupled to the transport in the free motion direction. For devices with the characteristic length of a few tens of nanometers, the transport of the electrons along the axis of the wire can be considered semiclassical, and it can be dealt with by the multi-sub-band Boltzmann transport equations (MBTE). By taking the moments of the MBTE, a hydrodynamic model has been formulated, where explicit closure relations for the fluxes and production terms (i.e., the moments on the collisional operator) are obtained by means of the maximum entropy principle of extended thermodynamics, including the scattering of electrons with phonons, impurities and surface roughness scattering. Numerical results are shown for a SiNW transistor

Low-field electron mobility evaluation in silicon nanowire transistors using an extended hydrodynamic model

Silicon nanowires (SiNWs) are quasi-one-dimensional structures in which electrons are spatially confined in two directions and they are free to move in the orthogonal direction. The subband decomposition and the electrostatic force field are obtained by solving the Schrödinger–Poisson coupled system. The electron transport along the free direction can be tackled using a hydrodynamic model, formulated by taking the moments of the multisubband Boltzmann equation. We shall introduce an extended hydrodynamic model where closure relations for the fluxes and production terms have been obtained by means of the Maximum Entropy Principle of Extended Thermodynamics, and in which the main scattering mechanisms such as those with phonons and surface roughness have been considered. By using this model, the low-field mobility of a Gate-All-Around SiNW transistor has been evaluated

Optics and Quantum Electronics

Contains table of contents for Section 2 and reports on eleven research projects.Joint Services Electronics Program Contract DAAL03-89-C-0001National Science Foundation Grant EET 87-00474U.S. Air Force - Office of Scientific Research Contract F49620-88-C-0089Charles S. Draper Laboratory Contract DL-H-404179National Center for Integrated PhotonicsNational Science Foundation Grant ECS 87-18417NEC Research InstituteNational Science Foundation Grant ECS 85-52701Medical Free Electron Laser Program Contract N00014-86-K-0117National Institutes of Health Grant 5-RO1-GM35459Lawrence Livermore National Laboratory Contract B048704U.S. Department of Energy Grant DE-FG02-89-ER14012Columbia University Contract P016310

Global existence for the system of the macroscopic balance equations of charge transport in semiconductors

AbstractGlobal existence of a solution to the nonlinear balance equations of charge transport in semiconductors based on the maximum entropy principle [Contin. Mech. Thermodyn. 11 (1999) 307–325; Contin. Mech. Thermodyn. 12 (2000) 31–51] is proven for a typical 1D problem under certain restrictions on the doping profile and the initial data

Numerical study of the systematic error in Monte Carlo schemes for semiconductors

The paper studies the convergence behavior of Monte Carlo schemes for semiconductors. A detailed analysis of the systematic error with respect to numerical parameters is performed. Different sources of systematic error are pointed out and illustrated in a spatially one-dimensional test case. The error with respect to the number of simulation particles occurs during the calculation of the internal electric field. The time step error, which is related to the splitting of transport and electric field calculations, vanishes sufficiently fast. The error due to the approximation of the trajectories of particles depends on the ODE solver used in the algorithm. It is negligible compared to the other sources of time step error, when a second order Runge-Kutta solver is used. The error related to the approximate scattering mechanism is the most significant source of error with respect to the time step