A COMPARISON OF BASE CURRENT REVERSAL AND BIPOLAR SNAPBACK IN ADVANCED N-P-N BIPOLAR-TRANSISTORS

It is argued that base current reversal in an advanced n-p-n bipolar transistor arises from the same physical mechanism as classical bipolar snapback. Measurements of the bipolar snapback voltage, BV(CEO), and of the collector-emitter voltage required for base current reversal, V(CE}IBr), are identical over a range of variation in transistor design and over more than eight orders of magnitude in collector current. The minimum or "sustaining" values for BV(CEO), or V(CE}IBr), should be used for the purposes of bipolar device design rather than the larger "trigger" value measured at very low current levels. The former is an indication of electric field strength in the collector-base depletion region while the latter is a monitor of the level of the nonideal base current component. Measurement of base current reversal provides a more consistent and less destructive technique of characterizing bipolar sustaining voltage.