JFET Hardening and High Dose Rate Study.
GENERAL ELECTRIC CO PHILADELPHIA PA RE-ENTRY SYSTEMS DEPT
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This document reports the results of a study to assess transient response hardening techniques for JFETs and to investigate their high dose rate behavior. The hardening analysis shows that by minimizing the device area, and using gold doping or a built-in E-field in the substrate, the JFET response can be made less than the response of typical transistor packages. The lowest response is achieved by JFETs on sapphire. The high dose rate analysis yielded models which establish upper and lower bounds on the photocurrent in the high injection region. Measurements of JFET photocurrent comply with the expected response. The channel response of JFETs is shown to be small at high dose rates, and SCEPTRE predictions of secondary photocurrent at high dose rates agree well with experimental data. Pulse injection measurements on low voltage devices showed burnout levels comparable to diodes, while high voltage units were much more sensitive, apparently due to surface instability. The power dissipation required to enter second breakdown was roughly comparable, with or without radiation. Author
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