The advective upstream splitting method (AUSM) developed for fluid dynamics
problems has been applied to solving hydrodynamic semiconductor equations coupled
with the Poisson’s equation. In the AUSM, the flux vectors of a fluid system are split
into a convective component and a diffusive pressure component. Discretization of these
two physically distinct fluxes is thus performed separately in AUSM. Application of the
developed hydrodynamic AUSM to a GaAs MESFET with a gate length of 0.1 μm has
demonstrated its simplicity, efficiency and effectiveness in dealing with the highly
nonlinear hydrodynamic device system.

Min Shen

Wai-Kay Yip

Ming-C. Cheng

J. J. Liou

An Upstream Flux Splitting Method
for Hydrodynamic Modeling
of Deep Submicron Devices

We have performed a three-dimensional statistical simulation of the threshold voltagedistribution of deep submicron nMOSFETs, as a function of gate length, dopingdensity, oxide thickness, based on a multigrid non-linear Poisson solver. We compareour results with statistical simulations presented in the literature, and show thatessentially only the vertical distribution of dopants has an effect on the standarddeviation of the threshold voltage.

E.  Amirante

G.  Iannaccone

B.  Pellegrini

Three-dimensional Statistical Modeling of the Effectsof the Random Distribution of Dopantsin Deep Sub-micron nMOSFETs

In this work we present comparisons between DSMC simulations of the full BTE and
deterministic simulations of a relaxation-time approximation for a nowadays size Si
diode. We assume a field dependent relaxation time fitted to give the same drift speed
(mean velocity) as DSMC simulations for bulk Si. We compute the density, mean
velocity, force field, potential drop, energy and I-V curves of both models and plot the
pdf of the deterministic relaxation-time model. We also compare the results to augmented
drift-diffusion models proposed in the literature to approximate the relaxation
time system in the quasi-ballistic regime. The quasi-ballistic and ballistic regimes are
distinguished by using local dimensionless parameters.

Marcello A. Anile

Jose A. Carrillo

Irene M. Gamba

Chi-Wang Shu

Approximation of the BTE by a Relaxation-time
Operator: Simulations for a 50 nm-channel Si Diode

Monte Carlo simulations of electron motion in GaAs/A1As superlattices with narrowmini-band width are performed to investigate the effect of a strong magnetic field onminiband conduction. In the quantum limit at low temperatures when the cyclotronenergy exceeds the miniband width, the miniband conduction is found to exhibit astrong suppression. This results from the quasi-one-dimensional states formed in thequantum limit and the restricted range of the scattering processes available to theconduction electrons. A small shoulder on the lower electric field side of the main peakis also found in marked contrast with Esaki-Tsu and Ignatov models.

N.  Mori

C.  Hamaguchi

L.  Eaves

P. C. Main

Numerical Studies of Miniband Conductionin Quasi-One-Dimensional Superlattices

The effects of electron–electron interaction on the electron distribution in n-channel
metal-oxide-semiconductor field-effect transistors (MOSFETs) are studied using the
Local Iterative Monte Carlo (LIMO) technique. This work demonstrates that electron–electron
scattering can be efficiently treated within this technique. The simulation results
of a 90 nm Si-MOSFET are presented. We observe an increase of the high energy tail of
the electron distribution at the transition from channel to drain.

T. Mietzner

J. Jakumeit

U. Ravaioli

Influence of Electron-Electron Interaction
on Electron Distributions in Short Si-MOSFETs
Analysed Using the Local Iterative
Monte Carlo Technique

A system based on frontier mesoscopic semiconductor technology, able to perform
the basic quantum operations needed for quantum computation, is proposed. The
elementary quantum bit (qubit) is defined as the state of an electron running along a
couple of quantum wires coupled through a potential barrier with variable height and/
or width. A proper design of the system, together with the action of Coulomb
interaction of two electrons representing two different qubits, allows the implementation
of basic one-qubit and two-qubit quantum logic gates. Numerical simulations confirm
the correctness of the hypothesis.

A. Bertoni

P. Bordone

R. Brunetti

C. Jacoboni

S. Reggiani

Numerical Simulation of Quantum Logic Gates
Based on Quantum Wires

The recent improvements in the performance of commodity computer have created very
favorable conditions for building high performance parallel machines from computer
clusters. These are very attractive for 3-D device simulation, necessary to model
properly carrier-carrier interaction and granular doping effects in deeply scaled silicon
devices. We have developed a parallel 3-D Monte Carlo simulation environment
customized for clusters using the Message Passing Library (MPI). The code has been
tested on the supercluster of NCSA at the University of Illinois. We present here test
results for an n-i-n diode structure, along with an analysis of performance for two
different domain decomposition schemes.

Asim Kepkep

Umberto Ravaioli

Brian Winstead

Cluster-based Parallel 3-D Monte Carlo
Device Simulation

A finite element method based on the least-squares scheme is developed for hydrodynamic
simulation of two-dimensional short-channel semiconductor devices. Although
this general-purpose finite element method has been shown in fluid dynamics to be more
universal to flow problems than other finite element approaches and has been applied in
recent years to a wide range of problems in fluid dynamics, it is still unfamiliar to the
semiconductor device community. Application of the developed hydrodynamic least
squares finite element method (LSFEM) to simulation of a 2D MESFET with a deep-submicron
gate has demonstrated its robustness and effectiveness for the hydrodynamic
device simulation.

A Generalized Finite Element
Method for Hydrodynamic
Modeling of Short-channel Devices

We have developed a full-band pseudopotential-based approach to describe semiconductor
nanostructures. The method relies on the bulk Bloch functions expansion of
the system wavefunction, which guarantee an efficient integration of the full-band
approach in self-consistent schemes where Schroedinger and Poisson equations are
solved iteratively. In order to gain efficiency of the method a suitable separation between
structure dependent and material dependent contributions to the system hamiltonian is
presented. Results are shown for a typical Si/SiO2 MOS structure.

Francesco Chirico

Aldo Di Carlo

Paolo Lugli

Self-consistent Full-band Modeling
of Quantum Semiconductor Nanostructures

Much of the potential of SiGe for p-MOSFET application is reduced by the lower thanexpected hole mobilities which are likely to be lowered by interface roughness scattering.The present paper analyses a hitherto unrecognised enhancement of interface scatteringand trapping process which arises from the complex hole dynamics in the warped heavyhole band.

J. R. Barker

J. R. Watling

Simulation of Enhanced Interface TrappingDue to Carrier Dynamics in Warped ValenceBands in SiGe Devices

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Computional Electronics; Papers Presented at The Seventh International Workshop on Computional Electronics

Published Special Issues

VLSI Design

Computional Electronics; Papers Presented at The Seventh International Workshop on Computional Electronics

Computional Electronics; Papers Presented at The Seventh International Workshop on Computional Electronics

Articles

An Upstream Flux Splitting Method for Hydrodynamic Modeling of Deep Submicron Devices

Three-dimensional Statistical Modeling of the Effects of the Random Distribution of Dopants in Deep Sub-micron nMOSFETs

Approximation of the BTE by a Relaxation-time Operator: Simulations for a 50 nm-channel Si Diode

Numerical Studies of Miniband Conduction in Quasi-One-Dimensional Superlattices

Influence of Electron-Electron Interaction on Electron Distributions in Short Si-MOSFETs Analysed Using the Local Iterative Monte Carlo Technique

Numerical Simulation of Quantum Logic Gates Based on Quantum Wires

Cluster-based Parallel 3-D Monte Carlo Device Simulation

A Generalized Finite Element Method for Hydrodynamic Modeling of Short-channel Devices

Self-consistent Full-band Modeling of Quantum Semiconductor Nanostructures

Simulation of Enhanced Interface Trapping Due to Carrier Dynamics in Warped Valence Bands in SiGe Devices