Numerical simulation and comparison of Si BJTs and Si/sub 1-x/Ge/sub x/ HBTs

Using the Monte Carlo method for the solution of the Boltzmann transport equation, the authors analyze the low-field carrier mobilities of strained layer and bulk Si and Si/sub 1-x/Ge/sub x/ alloys. Strained alloy layers exhibit higher low-field mobility compared with bulk Si at doping levels >10/sup 18/ cm/sup -3/ and for a Ge mole fraction x>