An investigation of collector-base transport in SiGe HBTs designed for half-Terahertz speeds

A new method is introduced to investigate electron transport in the collector-base space charge region of SiGe HBTs designed for half-Terahertz speeds. Using commercially-available Monte Carlo and hydrodynamic TCAD tools, one can eliminate the fundamental limitations of hydrodynamic models related to velocity overshoot and impact ionization. The method is verified in a 200-GHz SiGe technology and then applied to hypothetical 350-GHz and half-THz (500 GHz) SiGe HBTs. This new approach requires far less computational complexity than classical Monte Carlo tools.