Laser-Solid Interactions
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topics of active interest. Timeresolved laser techniques were reported in the picosecond and even subpicosecond regimes. In general, measurements of optical reflectivity and transmission as well as timeresolved x-ray diffraction and electrical conductivity and TEM studies of resulting material structures gave a picture of rapid (1lOpsec) conversion of high intensity electronic excitation to heat with rapid phase changes to, and subsequently from, the molten state. However, time-resolved Raman measurements in the nanosecond regime continue to present a puzzling and conflicting picture as both the measurements and their interpretation are refined. Maximum Raman temperatures well below the
Prof D. Turnbull, Harvard
R.A. Lemons (left), J. Narayan and W.L. Brown, Co-Chairmen
PAGE 12, MRS BULLETIN, NOVEMBER/DECEMBER 1982
melting point of silicon continue to be deduced under conditions in which other results indicate that melting occurs. Rapid thermal annealing of silicon and compound semiconductors is being pursued with an everexpanding array of non-laser heat sources. At the symposium, these included scanning electron beams, quartz halogen lamps, mercury arc lamps, vortex cooled argon arc lamps, and graphite strip heaters. Annealing was typically carried out in times of 0.1 to 10 seconds. Reports were presented of very high quality
and transient thermal processing of materials
material produced in this rapid, but not superfast, processing. Undoubtedly the technologically most exciting area discussed at the symposium was that of lateral epitaxy of silicon on insulating, noncrystalline substrates: SOI, or silicon-oninsulator. These crystal growing processes are being carried out under a number of different conditions by different workers. They involve a wide variety of heat sources from lasers to hot graphite strips. In general, they result in thin films of crystalline silicon with thicknesses from 0.2 to 100 micrometers and with grain sizes as large as millimeters. Control of the lateral growth interface by control of thermal gradients has reached a high degree of sophistication as has the understanding of the stabilization of the growth process. Very high quality devices are being fabricated in this material which promises to have a unique role in the production of dielectrically isolated devices and in very large and inexpensive device arrays. The symposium consisted of eight oral and one poster session. The oral sessions, which included 23 invited and 54 contributed papers, attracted audiences as large as 300, with particular interest in the sessions on energy transfer, phase transitions and crystallization of silicon on amorphous substrates. The display of
Principal Support Office of Naval Research (L. Cooper) Defense Advanced Research Projects Agency (S. Roosild) Department of Energy, Office of Basic Energy Sciences (M. Wittels) Army Research Office, Electronics Division (R. Reeber)
G.A. Rozgonyi (foreground), Bell Labs, at a Symposium A poster session
30 posters was available for study throughout the symp
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