Comparison of the Punch-Through and Non-Punch-Through IGT Structures

Abstract

The insulated gate transistor (IGT) has been modeled as a wide-base bipolar junction transistor (BJT) driven by a MOSFET. Therefore, the vertical wide-base BJT structure influences the following IGT characteristics: 1) the forward current-voltage characteristics, 2) the fall time/forward-voltage drop trade-offs, 3) the high-temperature blocking, and 4) the turn-off current tail. An IGT with punch-through (PT) BJT yields lower forward voltage than that of an IGT with non-punch-through (NPT) BJT due to the thinner base of the PT BJT structure. The punch-through IGT has lower off-state (leakage) current and also shorter turn-off current tail due to lower current gain of a PT BJT than that of an NPT BJT. Both PT and NPT IGT's have large safe operation areas.