Pre-turn-on source bipolar injection in graded NMOSTs

The influence of the pre-turn-on source bipolar injection on graded NMOST breakdown characteristics is investigated. Double-implanted As-P (n/sup +/n/sup -/) source-drain NMOS structures (DD NMOSTs) with different effective channel lengths, ranging from 1.15 to 9.15 mu m, are measured. Using a simple, but accurate, semi-empirical model for the transistor operating in the breakdown region, it is shown that the DD NMOST snapback voltage is substantially decreased due to the enhanced pre-turn-on source electron emission current.<
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