A new analytical expression of thermal diffusion coefficient <mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi>D</mml:mi><mml:mi>T</mml:mi></mml:msup></mml:mrow></mml:math> is derived. To the firstorder
approximation, it is given by (1+η)-1(D/<mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:mrow></mml:math>) rather than (1–η)(D/<mml:math id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:mrow></mml:math>) where
η=–(<mml:math id="E4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:mrow></mml:math>/η*)(∂η*/∂<mml:math id="E5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:mrow></mml:math>
) and η* represents the temperature-dependent bulk mobility.
This new transport coefficient is implemented in our 2-D hydrodynamic device
simulator and it seems to produce more reasonable results.

Ting-Wei Tang

Xinlin Wang

Haitao Gan

Meikei Ieong

An Analytic Expression of Thermal Diffusion
Coefficient for the Hydrodynamic Simulation
of Semiconductor Devices

An improved 3-D Monte Carlo simulation model is developed to treat the discreterandom dopant distribution in sub-0.1 &#956;m MOSFET. The new atomistic model is basedon a scattering rate calculation and an algorithm that take into account many-body effectsand the local variations of screening length according to impurity distribution and biasconditions.To validate this new approach low field electron drift mobility and diffusioncoefficient have been computed using simulation of 3D bars for 1015&#8211;1018 cm&#8211;3 rangeof average doping concentration. A good agreement is found between calculation andexperimental mobility data at 300 K.

S.  Barraud

P.  Dollfus

S.  Galdin

R.  Rengel

M. J. Martin

J. E. Vel&#225;zquez

An lonised-impurity Scattering Modelfor 3D Monte Carlo Device Simulation with DiscreteImpurity Distribution

The effect of scaling into deep decanano dimensions on the performance of pseudomorphic
high electron mobility transistors (pHEMTs) is extensively studied using
Monte Carlo simulations. The scaling of devices with gate lengths of 120, 70, 50 and
30nm is performed in both lateral and vertical directions. The devices exhibit a
significant improvement in transconductance during scaling, even though external
resistances become a limiting factor.

K. Kalna

A. Asenov

K. Elgaid

I. Thayne

Scaling of pHEMTs to Decanano Dimensions

As MOSFETs are scaled to deep submicron dimensions non-equilibrium, near ballistic,
transport in p-MOSFETs becomes important. Recent experimental data indicates that
as MOSFETs are scaled the performance gap between n and p-channel shrinks. Nonequilibrium
transport effects and performance potentials of ‘Well Tempered’ Si p-
MOSFETs with gate lengths of 50 and 25 nm are studied. Monte Carlo and calibrated
Drift Diffusion simulations of these devices provide a quantitative estimate of the
importance and the influence of non-equilibrium transport on submicron device
performance. A possible explanation for the closing performance gap between n- and
p-channel MOSFETs is offered.

J. R. Watling

Y. P. Zhao

J. R. Barker

Non-Equilibrium Hole Transport in Deep Sub-Micron
Well-Tempered Si p-MOSFETs

Turn-on characteristics of GaAs MESFETs and HEMTs are simulated when the gate voltage is changed abruptly. The gate-lag or slow current transient becomes more pronounced when the off-state gate voltage is more negative, because the surface-state effects or substrate-trap effects become more significant. Changes of I–V curves of GaAs MESFETs, when the drain voltage is swept with different speeds, are also simulated. When the swept time is short, the curve shows overshoot-like behavior and the kink disappears, indicating that the I–V characteristics should be quite different between DC and RF conditions.

K. Horio

Y. Mitani

A. Wakabayashi

N. Kurosawa

Simulation of Drastic Lag Phenomena in GaAs-Based FETs for Large Voltage Swing

A hydrodynamical model for electron transport in silicon semiconductors, free of any
fitting parameters, has been formulated in [1,2] on the basis of the maximum entropy
principle, by considering the energy band described by the Kane dispersion relation and
by including electron-non polar optical phonon and electron-acoustic phonon
scattering.In [3] the validity of this model has been checked in the bulk case. Here the
consistence is investigated by comparing with Monte Carlo data the results of the
simulation of a submicron n+–n–n+ silicon diode for different length of the channel,
bias voltage and doping profile.The results show that the model is sufficiently accurate for CAD purposes.

O. Muscato

V. Romano

Simulation of Submicron Silicon Diodes
with a Non-Parabolic Hydrodynamical Model Based
on the Maximum Entropy Principle

Degradation of thin film interconnects and ultra-thin dielectrics is studied within a
stochastic approach based on a percolation technique. The thin film is modelled as a
two-dimensional random resistor network at a given temperature and its degradation is
characterized by a breaking probability of the single resistor. A recovery of the damage
is also allowed so that a steady-state condition can be achieved. The main features
of experiments are reproduced. This approach provides a unified description of
degradation and failure processes in terms of physical parameters.

C. Pennetta

L. Reggiani

Gy. Trefán

R. Cataldo

G. De Nunzio

A Percolative Approach to Reliability of Thin Film
Interconnects and Ultra-thin Dielectrics

This paper discusses the use of established Technology Computer-Aided Design
(TCAD) tools and methodologies for the study of charge transport in molecular biology
systems, like ionic channels, that display a behavior analogous to electronic devices.
Continuum drift-diffusion and Monte Carlo methods can be applied to analyze steady-state
and transient behavior of ionic channels over time scales that cannot be resolved
practically by detailed molecular dynamics or quantum approaches. The difficult ion-water
interaction can be lumped phenomenologically into mobility or scattering rate
parameters, while the solution of Poisson equation over the complete domain provides a
simple way to include external boundary conditions and image force effects at dielectric
discontinuities. We present here some recent results of 3-D simulations for a gramicidin
ion channel, obtained using the rapid prototyping computational platform PROPHET.

K. Hess

U. Ravaioli

M. Gupta

N. Aluru

van der Straaten

R. S. Eisenberg

Simulation of Biological Ionic Channels by Technology
Computer-Aided Design

As MOSFET devices within the deep sub-micron regime are modelled, it is no longer
feasible to represent the charged dopants by a continuous charge distribution. In this
regime an ensemble of devices, each with different spatial distributions and the number
of dopants, must be modelled. However, it is computationally prohibitive to solve for
the full Coulomb interaction required for particle simulators, especially for an ensemble
of devices. To address this point, the paper focuses on the issue of modelling the
dynamics in the presence of discrete carrier–carrier scattering and carrier-fixed impurity
scattering which is suitable for efficient simulations of large ensembles of devices.

J.   R. Barker

Soft Sphere Model for Electron Correlation
and Scattering in the Atomistic Modelling
of Semiconductor Devices

Charge transport has been simulated in a novel two quantum well InGaN/GaN lightemitting diode. Asymmetric tunnelling for holes and electrons has been used to enhancethe quantum efficiency of the diode. A self-consistent solution of Poisson andSchr&#246;dinger equations has been used to obtain the band profile, energy levels andwave functions. Transport in the bulk nitride has been simulated by a drift diffusionmodel. Lattice strain and the resulting piezoelectric field effects have been shown toinfluence the device characteristics.

D.  Oriato

Alison B. Walker

W. N. Wang

Simulation of Widebandgap Multi-QuantumWell Light Emitting Diodes

About this journal

Journal profile

Meet the editorial board

Editor spotlight

Submit your proposal

Do you think there is an emerging area of research that really needs to be highlighted? Or an existing research area that has been overlooked or would benefit from deeper investigation? Raise the profile of a research area by leading a Special Issue.

Special Issues

title

https://images.hindawi.com/journals/vlsi/vlsi.banner.jpg

twitter:card

twitter:site

twitter:title

twitter:url

twitter:image

VLSI Design | Hindawi

VLSI Design

This Issue is now open for submissions.
Papers are published upon acceptance, regardless of the Special Issue publication date.

Call for papers

John Barker

Jeremy Watling