Large-signal modeling of InP/InGaAs single heterojunction bipolar transistors including thermal and impact ionization effects

Abstract

In this thesis, modeling of InP/InGaAs single heterojunction bipolar transistors (SHBTs) has been presented. Also, the thermal characteristics of InP/InGaAs SHBTs have been discussed. The small-signal model parameters of InP/InGaAs SHBTs were extracted and optimized at various bias operating conditions such as the cut-off, open-collector and active mode. To verify the small-signal model, the multi-bias S-parameter measurements under active mode bias conditions were performed, and the good agreement between the measured and modeled data was obtained at various bias conditions. The thermal characteristics of InP/InGaAs SHBTs have been analyzed and discussed on the theoretical and experimental results. In order to investigate the contribution of impact ionization and built-in potential reduction effects to thermal behavior of the devices, the thermal related parameters, such as temperature dependence of impact ionization multiplication factor, thermal-electric feedback coefficient and thermal resistance, were extracted. Using these extracted parameters, the built-in potential reduction and impact ionization effects in the common-emitter I-V characteristics of InP/InGaAs SHBTs have been analyzed. Based on the results obtained in thermal characteristics of InP SHBTs, a new large-signal model of InP/InGaAs SHBTs has been developed which includes self-heating and impact ionization effects. The self-heating and impact ionization effects observed from the InP-based SHBTs have been modeled through a macro modeling approach. The dependence of impact ionization on VCB and junction temperature has been modeled using a feedback current source and a temperature dependent voltage source. The model implemented in HP-ADS has been verified by comparing the measured and simulated data. Good agreement between the measured and simulated data has been achieved in the overall device performance of dc, multi-bias small-signal S-parameter and large-signal microwave p...