Dead-space effects under near-breakdown conditions in AlGaAs/GaAs HBT's

By using a self-consistent Monte Carlo simulation, the authors demonstrate the importance of dead-space effects in the near-avalanche regime of AlGaAs/GaAs HBTs. They show that the space-dependent ionization coefficient reaches its maximum inside the collector region, displaced by several hundred angstroms from the peak electric field at the collector-base junction, and from the maximum of the carrier average energy. A delay equation is proposed that overcomes the failure of local models in describing such effects.>