Second Breakdown in the Presence of Intense Ionizing Radiation and Related Studies.
AUBURN UNIV ALA DEPT OF PHYSICS
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The role of intense pulses of ionizing radiation on the second breakdown transition is investigated using silicon-on-sapphire p - n - p diodes. Superimposed on a high amplitude current pulse is a pulse of intense ionizing radiation from a Q-switched neodymium-glass laser. Photocurrents proportional to the radiation intensity are observed all the way to the threshold of damage by laser irradiation alone. The photocurrents do not affect the second breakdown transition until the intensity of the laser beam is close to that for destruction by the laser alone. In a study of the damage produced by the laser beam alone, no heating effects are detectable right up to the damage threshold. Damage occurs by vaporization of the silicon the absorption coefficient of silicon changes within a few nanoseconds by more than a factor of 10 at the damage threshold. The mechanism of absorption is unknown. Second breakdown behavior is described in SOS diodes using double pulse excitation. Second breakdown in thin film MOSFET devices is described for several device geometries. Other studies include filamentation in plane silicon films, dynamic temperature measurements on SOS diodes, annealing of second breakdown damage, and microstructure of bulk transistors. Modified author abstract
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