Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Learn the basic properties and designs of modern VLSI devices, as well as the factors affecting performance, with this thoroughly updated second edition. The first edition has been widely adopted as a standard textbook in microelectronics in many major US universities and worldwide. The internationally-renowned authors highlight the intricate interdependencies and subtle tradeoffs between various practically important device parameters, and also provide an in-depth discussion of device scaling and scaling limits of CMOS and bipolar devices. Equations and parameters provided are checked continuously against the reality of silicon data, making the book equally useful in practical transistor design and in the classroom. Every chapter has been updated to include the latest developments, such as MOSFET scale length theory, high-field transport model, and SiGe-base bipolar devices.

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Fundamentals of Modern VLSI Devices

A prevalent and pervasive view of designing is that it can be modeled using variables and decisions made about what values should be taken by these variables. The activity of designing is carried out with the expectation that the designed artifact will operate in the natural world and the social world. These worlds impose constraints on the variables and their values; so, design could be described as a goal-oriented, constrained, decision- making activity. However, design distinguish- es itself from other similarly described activities not only by its domain but also by additional necessary features. Designing involves exploration, exploring what variables might be appropriate. The process of explo- ration involves both goal variables and deci- sion variables. In addition, designing involves learning: Part of the exploration activity is learning about emerging features as a design proceeds. Finally, design activity occurs within two contexts: the context within which the designer operates and the context produced by the developing design itself. The designer’s perception of what the context is affects the implication of the context on the design. The context shifts as the designer’s perceptions change. Design activity can be now characterized as a goal-oriented, con- strained, decision-making, exploration, and learning activity that operates within a con- text that depends on the designer’s percep- tion of the context.

Design Prototypes: A Knowledge Representation Schema for Design

Creativity: Flow and the Psychology of Discovery and Invention

Cognitive engineering

Phononic engineering of silicon using dots on the fly e-beam lithography and plasma etching

Carrier injection at silicide/silicon interfaces in nanowire based-nanocontacts

An optimal high contrast e-beam lithography process for the patterning of dense fin networks

A detailed study of the formation of iridium silicide obtained by ultrahigh vacuum annealing and atmospheric rapid thermal processing is proposed using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and electrical characterizations. Using XPS analysis, the stoichiometry of each silicide phase (IrSi, IrSi1.6) is identified. A model based on the variation of the measured intensity of the Ir 4f spectra is used to obtain the kinetic coefficients of reaction of Ir silicidation (EA=2.48eV, D0=9cm2∕s). TEM cross sections indicate that the roughness of the silicide∕silicon interface increases with temperature. Lastly, electrical characteristics are used to identify the optimum annealing temperature to obtain an iridium silicide contact with the lowest Schottky barrier height to holes.

Kinetics, stoichiometry, morphology, and current drive capabilities of Ir-based silicides

This paper proposes to study the impact of a moderate variation of the channel doping level on the electrical performance of p-type Schottky-barrier (SB) MOSFETs. First, it has been found that a moderate increase of the acceptors doping level leads to a reduction of the Schottky-barrier height (SBH) but does not affect the silicide reaction. In the case of PtSi, the SBH on p-type silicon at 5 × 1015 cm−3 is 0.15 eV whereas an increase of the doping level by two decades decreases the barrier by 60 meV. The integration of PtSi MOSFETs on moderately doped channel (5 × 1017 cm−3) was successfully achieved, demonstrating an overall 60% improvement in current drive at Lg = 100 nm. This enhanced performance is attributed to the barrier height reduction related to the beneficial band bending induced by p-type dopants. The considered doping levels are still in a sufficiently low range not to affect the carrier mobility in the channel. A complete study, including comparison of Ion, Ioff, immunity against short channel effects (Swing and DIBL), is presented.

Emmanuel Dubois

Papers

Phononic engineering of silicon using dots on the fly e-beam lithography and plasma etching

Carrier injection at silicide/silicon interfaces in nanowire based-nanocontacts

An optimal high contrast e-beam lithography process for the patterning of dense fin networks

Kinetics, stoichiometry, morphology, and current drive capabilities of Ir-based silicides

Impact of channel doping on Schottky barrier height and investigation on p-SB MOSFETs performance