SiGe:C HBT transit time analysis based on hydrodynamic modeling using doping, composition and strained dependent SiGe:C carriers mobility and relaxation time

We present an original method for the detailed evaluation of different device region contributions to the whole SiGe:C heterojunction bipolar transistor transit time in the frame of modeling studies. This method is based on AC analysis with structures of several base widths. The two-dimensional hydrodynamic solver relies on analytical models of electron and hole mobilities, and of energy relaxation times, calculated from results of the Boltzmann Transport Equation in highly acceptor doped and strained SiGe:C, using a full band Monte Carlo solver. The simulation results are compared to DC and AC measurements and exhibit good agreement. The proposed transit time analysis scheme and the analytical model for mobilities and energy relaxation times may be used for device optimization, toward highest dynamic performances.

► An original method to perform transit time analysis in SiGe HBT is described.
► It relies on analytical models of carrier mobilities and of energy relaxation time.
► These models are fitted from full-band Monte Carlo simulations of SiGe:C system.
► These models are implemented in a hydrodynamic solver.
► Modeling results show good agreement with measurements.