Analysis of avalanche regime in InP HBT´s using physical simulation implementation in a DC model

This paper deals with the investigation of collector current I_c increase in InP/InGaAs/InP HBT designed for rapid digital signal processing in optical fibre telecommunication systems. Indeed, at high base-collector voltage, carrier generation by impact ionization as well as carrier tunnelling mechanisms in the multi-layer collector initiate I_c increase previous to the avalanche regime. Then, the characterisation of DC operation at low level injection allows to extract parameters which are included in a Gummel-Poon model modified to consider the impact ionisation influence. The physical simulation leads to identify parasitic elements as a current source accounting for carrier multiplication.