-
[show abstract]
[hide abstract]
ABSTRACT: Superconducting magnetic energy storage (SMES) systems can be used to improve power supply quality and reliability. In addition, large amounts of power can be drawn from a small stored energy supply. Nevertheless, the strong electromagnetic force caused by high magnetic fields and coil current is a serious problem for SMES. To cope with this problem, we propose a new coil design, the tilted toroidal coil (TTC). The TTC, obtained from the toroidal field coil (TFC) system by varying two pitching angles, allows the balancing of the electromagnetic force in the major radius direction, maintaining the same manufacturing simplicity of the TFC system. After determining balanced configurations through computer simulation, we built an experimental device to confirm the feasibility of the balancing effect.
IEEE Transactions on Magnetics 12/2003; · 1.36 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A new microscopic silicon model for hole transport at high electric fields featuring two valence bands in a finite Brillouin zone is presented. The band parameters and the electron-phonon coupling constants were determined by best fitting the density of states and the experimental and theoretical results for transport properties in the low and intermediate field-strength range. Hole impact ionization has been introduced following a new scheme that goes beyond the limitations contained in the Keldysh formula. The present model, coupled to an analogous model already developed for electrons, allows study of bipolar transport silicon devices. Applications to bulk Si and Si p-MOSFETs are presented.
Semiconductor Science and Technology 12/1998; 7(3B):B597. · 1.72 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The noise arising from double row selection in the encoder ROM of
a parallel ADC appreciably depends upon the chosen coding. A procedure
for comparing the performance of different codes in the case of double
selections is introduced and applied to the well known Gray and
quasi-Gray codes. A novel flipped brick code is proposed, which performs
better than both the quasi-Gray and Gray codes in terms of noise power
and exhibits a simpler conversion to binary code than the Gray
code
Electronics, Circuits and Systems, 1998 IEEE International Conference on; 02/1998
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper we present an in-depth analysis of Quantum Yield
(QY) data by means of Full Band Monte Carlo (FBMC) simulation including
data from stressed oxides. The effect of device structure and initial
energy distribution on QY efficiency is explored and the consequences of
oxide stress on QY data are analyzed. In particular, we show that: (a)
there is universal shape for QY curves in fresh oxides independent of
oxide thickness and substrate doping; (b) QY data can be used to gain
important insight into possible Stress Induced Leakage Current (SILC)
mechanisms and discriminate between different SILC models
Electron Devices Meeting, 1997. IEDM '97. Technical Digest., International; 01/1998
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper we investigate some of the numerical approximations
involved in the development of Full Band Monte Carlo (FBMC) programs for
semiconductor (silicon) devices. In particular, we focus on how the
accuracy in describing the Full Band silicon structure affects
quantities such as the density of states (DoS), scattering rates,
velocity field curves, etc
Simulation of Semiconductor Processes and Devices, 1997. SISPAD '97., 1997 International Conference on; 10/1997
-
[show abstract]
[hide abstract]
ABSTRACT: The theoretical study of a novel Si/SiGe structure combining the advantages of buried channel MOS devices and conventional SiGe FET's is presented. A self-consistent one-dimensional Schrodinger-Poisson simulator has been developed to evaluate the gate dependence of electron effective mobility in the zero-field limit. Room temperature peak mobility values greater than 2800 cm/sup 2//Vs are predicted. The proposed structure shows also good turn-on characteristic and linear transconductance behavior, which represents a significant feature in view of possible technology applications.
IEEE Electron Device Letters 03/1996; · 2.85 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper provides an investigation on the effects of deep level
traps on the large-signal I-V characteristics of GaAs MESFETs by means
of measurements and physics-based device simulations; results give clear
indications that pulsed I-V measurements are sufficient in order to
characterize large-signal AC device operation and provide a good
physical basis for circuit-level large signal MESFET models
Electron Devices Meeting, 1995., International; 01/1996
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper a quantitative study of the electron energy
distribution in silicon devices at low applied voltages is carried out
by means of Monte Carlo simulations including the main mechanisms
involved in the process of carrier heating. We present a clear-cut
interpretation of the build up of the electron distribution at energies
higher than that provided by the applied electric field (qV, V being the
total voltage drop). Electron-electron interaction is analyzed and shown
to be an effective process for the enhancement of the high-energy
electron population
Electron Devices Meeting, 1995., International; 01/1996
-
[show abstract]
[hide abstract]
ABSTRACT: The behavior of low field effective electron mobility (EEM) in
Si/SiGe FETs has been investigated. The results have been obtained
solving self-consistently the one dimensional Poisson and Schrodinger
equations. Strain induced band splitting has been included in the
framework of the model-solid theory (MST). The EEM has been computed in
the relaxation-time approximation, including scattering due to optical
phonons, elastic acoustic phonons, and surface roughness. The scattering
rates have been computed consistently with the 2-D character of the
electron gas (2DEG). First-order perturbation theory has been used to
account for non parabolic energy dispersion in the scattering rate
calculations. The simulator has been applied to study the EEM dependence
on gate voltage and device structure. A homogeneous Monte Carlo
simulator (HMCS) consistent with the 2-D nature of the electron gas has
also been developed and resulting drift velocity and mean energy
behavior as a function of the parallel electric field are also presented
Electron Devices Meeting, 1994. IEDM '94. Technical Digest., International; 01/1995
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we present a unified model for electron and hole
transport and injection into the gate oxide of MOS devices based on our
Monte Carlo simulator BeBoP. The injection problem has been tackled by
means of a simplified analytical solution of the Schrodinger equation
across the Si-SiO<sub>2</sub> gate barrier, that leads to a direct
calculation of the transfer probability from Si into the gate
(P<sub>Si-G</sub>). With appropriate choice of parameters the model
reproduces a wide set of experiments sensitive to low and high energy
transport phenomena, including for the first time homogeneous hole
injection data
Electron Devices Meeting, 1994. IEDM '94. Technical Digest., International; 01/1995
-
[show abstract]
[hide abstract]
ABSTRACT: This paper presents an extension of the theoretical approach for both the short‐ and long‐range components of the Coulomb interaction among carriers in semiconductors to the case of an arbitrary isotropic multiband model, devised for Monte Carlo simulation of silicon devices. The analytical and numerical aspects of the model are discussed in detail. Results for the effect of the Coulomb interaction on the carrier distribution function and on the energy‐loss properties of the carrier gas are presented for the case of electrons in homogeneous and inhomogeneous silicon structures.
Journal of Applied Physics 12/1994; · 2.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A numerical method for the determination of isotropic band models
has been developed and applied to silicon. The resulting model
accurately approximates both density of states and group velocity of the
corresponding anisotropic band structure, thus providing an excellent
agreement with both the collision and nonhomogeneous terms of the
Boltzmann transport equation. The model, represented by a simple set of
energy-wave vector tables, has been implemented in a Monte Carlo device
simulator, but can also be extended to alternative methods for solving
the Boltzmann equation. Simulation of homogeneous silicon shows a very
good agreement with available experimental data. Comparison with results
obtained using the complete anisotropic band structure, both in
homogeneous and nonhomogeneous silicon devices, confirms the validity of
the model
IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 10/1993; · 1.27 Impact Factor
-
VLSI Process and Device Modeling, 1993. (1993 VPAD) 1993 International Workshop on; 06/1993
-
[show abstract]
[hide abstract]
ABSTRACT: A test structure is designed in order to investigate an original
procedure for accurately reproducing on a target automatic test
equipment (ATE) for digital ICs the same timing setup used by a source
ATE. The aim is to settle manufacturer/customer contestations.
Implementation in a 2.4-μm CMOS technology is reported, together with
preliminary experimental results
Microelectronic Test Structures, 1993. ICMTS 1993. Proceedings of the 1993 International Conference on; 04/1993
-
[show abstract]
[hide abstract]
ABSTRACT: An optimization of transport parameters for Monte Carlo simulation
of electrons in silicon has been performed in order to obtain
quantitative agreement between simulations and experiments when dealing
with problems involving very-high-energy electrons, such as impact
ionization and the injection of hot-electrons into the gate oxide of
MOSFETs. An original physically based model for electron injection into
SiO<sub>2</sub> is proposed which consistently accounts for both
thermionic injection and tunneling of hot electrons. The results of
numerical simulations are compared with experimental data on nMOSFET
substrate current and bulk hot-electron gate current
Electron Devices Meeting, 1991. IEDM '91. Technical Digest., International; 01/1992
-
[show abstract]
[hide abstract]
ABSTRACT: As isotropic model for the silicon band structure which accurately approximates both density of states and group velocity of the real anisotropic band structure and yields excellent agreement with both the collision and nonhomogeneous terms of the Boltzmann transport equation has been developed. The model, represented through a simple set of energy-wave vector tables, has been implemented in a Monte Carlo device simulator, but can also be extended to alternative methods for solving the Boltzmann equation. Simulations of homogeneous silicon bars show a very good agreement with available experimental data
Electron Devices Meeting, 1991. IEDM '91. Technical Digest., International; 01/1992
-
[show abstract]
[hide abstract]
ABSTRACT: Monte Carlo simulations of high-energy electrons and holes in Si
n-MOSFETs are presented. Key features of this work include the use of a
suitable silicon model for carrier transport at high electric fields, an
original impact ionization model, and sophisticated numerical techniques
to speed up the calculation. The case of submicrometer Si n-MOSFETs is
considered as a relevant application
IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 11/1991; · 1.27 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A study is presented on the effects of voltage scaling on
hot-electron phenomena and intrinsic device performance in submicrometer
MOSFETs. A Monte Carlo device simulator featuring a suitable band model
for high-energy electrons is used. An interesting finding is that at
very short channel lengths the high energy tail of the electron
distribution function, the most important quantity in determining
hot-carrier reliability, is controlled by the applied bias and not by
local electric fields. As confirmed by recently reported experimental
work, the results of this study indicate that the conventional, linear
voltage scaling can be weakened using a more relaxed voltage reduction
law that leads to improved performance without threatening device
reliability
IEEE Transactions on Electron Devices 09/1991; · 2.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Carrier transport across the semiconductor space-charge region of
a silicon triangular barrier diode was investigated by a Monte Carlo
simulation. Oscillations of the electron mean kinetic energy are
observed as a function of position along the uphill slope of the barrier
under bias. At a given point on the uphill slope, the energy
distribution function shows an oscillatory behavior, with a periodicity
corresponding to the optical phonon energy. These oscillations are shown
to be due to the nonequilibrium dynamics of the electron interaction
with optical phonons in the situation when other inelastic electron
scattering processes are negligible. The energy oscillations are
superimposed on a smooth cooling of the distribution in the transport
toward the top of the barrier, as current flows through the system. A
comparison with the thermionic theory quantifies the importance of
nonequilibrium effects in short-range electronic transport
IEEE Transactions on Electron Devices 04/1991; · 2.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A simple and efficient model for first-order simulation of the
writing of n-channel erasable programmable ROM (EPROM) cells is
presented. It allows the current injected into the gate insulator of the
cell transistor to be calculated, accounting (at first order) both for
the nonMaxwellian form of the electron energy distribution and for the
nonlocal nature of carrier heating. The model is implemented as a
postprocessor of a two-dimensional device simulator, and it is validated
by means of a comparison with experimental data obtained with devices
with effective channel lengths ranging from 1.4 to 0.5 μm
IEEE Transactions on Electron Devices 04/1991; · 2.32 Impact Factor
