This area of research is designed to focus on the practical limiting speed of switching devices intended for ultrahigh-speed digital applications. Emphasis is on the need to demonstrate the generation of logic at very high rates with integrated electronic, optoelectronic, and optical devices which in principle are capable of achieving or exceeding 100 Gbit/sec switching rates. Methods for generation, propagation, and processing of signals characterized by time constants ranging from 10 picoseconds to 10 femtoseconds are studied as new materials and new techniques are developed.

Methods for selectively affecting the surface of materials with the aid of laser radiation is investigated for the pur- pose of novel fabrication and modification of electronic de- vices and components. Nonequilibrium thermodynamic and quantum electronic conditions are produced at the surface of materials, giving rise to conditions capable of altering reaction rates for thermal, photochemical, and physical processes. Thin films that have been prepared under conditions of enhanced diffusion, enhanced com- pound formation, and nonequilibrium alloying are under investigation.

Ultrashort signals such as in ultrahigh-speed digital logic are characterized by a very rich frequency content. In the design of future systems, accurate representation of the propagation of such signals and the interaction of such signals with devices must be carried out in great detail. Channel and device characterization is formulated for numerical analysis approaches. Corresponding algorithms are tested for computer-aided design implementation.

Development of analytical tools aimed at characterizing the performance of digital devices when operated at ultrahigh rates is the focus of this project. The use of high-precision characterization of transmission channels and active devices is emphasized throughout. The applicability of modeling procedures to accurate signal management analysis in ultrahigh-speed digital networks of high complexity is stressed in this effort.

A program for developing computer-aided tools for high-precision electronic and electromagnetic characterization of devices and interconnections intended for operation at high- and ultrahigh digital rates is in place in our laboratory. The goals are modeling interconnected digital devices and characterizing the interconnecting channels for their performance and manufacturability. Numerical methods are used extensively for characterizing semiconductors, conventional conductors, and modern superconductors. Extensive use is made of computer simulation capable of taking into account principal as well as high-order effects of signal degradation. Tools based on picosecond instrumentation and high-frequency network analysis are implemented for validation of all work.