In this paper we describe a set of measurements representing a complete characterization of impact-ionization effects in bipolar transistors. We demonstrate that impact-ionization significantly influences the dependence of base resistance on current and voltages applied to the device. A dc method for the simultaneous extraction of all parasitic resistances in bipolar transistors is presented. The method can separate the influence of current-crowding on the base resistance from that of base width and conductivity modulation; the collector parasitic resistance is measured in the active region. Starting from the parameters extracted by means of these techniques, a complete and accurate circuit-model of impact-ionization effects can be defined.
Influence of impact-ionization-induced base current reversal on bipolar transistor parameters / L., Vendrame; E., Zabotto; A., Dal Fabbro; A., Zanini; Verzellesi, Giovanni; E., Zanoni; A., Chantre; Pavan, Paolo. - In: IEEE TRANSACTIONS ON ELECTRON DEVICES. - ISSN 0018-9383. - STAMPA. - 42:(1995), pp. 1636-1646.