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Abstract: Vertical and horizontal scaling is aggressively used to increase frequency performances of SiGe Heterojunction Bipolar Transistors. As a result, the evaluation of the extrinsic electrostatic capacitances becomes increasingly important. In this article, we investigate the electrostatic parasitic capacitance in 230–335GHz SiGe transistor technologies. We compare measured electrostatic capacitances with calculations based on a finite elements modelling. We conclude that the influence of the parasitic capacitances only screens the intrinsic performances of the devices by 10–14% but an accurate estimation of theses parasitics must be included in the design of next generation SiGe HBT. [Copyright &y& Elsevier]

A direct matrix solution of the Boltzmann transport equation is developed to investigate impact ionization and other hot carrier phenomena in compound semiconductor devices. The model is applied to GaAs. A full-band calculation of the semiconductor structure is performed using k·p theory. An original determination of the distribution function in k-space as a function of electric field and temperature is achieved. The dependence of the ionization rate on energy, of the drift velocity and of the ionization coefficient on electric field are in good agreement with Monte Carlo data at 300 K and validate the modeling approach. The variation of the impact ionization coefficient on temperature and electric field in GaAs is discussed. [Copyright &y& Elsevier]

This paper reports an extensive investigation of high frequency figures of merit versus temperature carried out on SiGe:C bipolar transistors with several base doping and activation annealing conditions. The best fT''s are 188 and 278 GHz at 300 and 75 K, respectively. Contributions to total emitter collector delay are discussed and an original method based on collector capacitance measurement is proposed to calculate the collector transit time. [Copyright &y& Elsevier]