The Calculation Of The Parameters Of SiGe Marerial

In this paper, the intrinsic carrier concentration, the minority carrier concentrationand the ratio of hole concentration to impurity concentration are calculated analyticallywith the varing of the temperature T, Ge fraction x and doping concentration. A model forthe built-in electric field is developed and the built-in electric field is calculated analyticallywith the varing of doping concentration and Ge fraction in the base. The model is suitablefor Gaussian doping distribution with different Ge profiles in the base (e.g., triangle, box-triangle). In the paper, much improvement has been gained. First, the new formulas ofvalence band effective states and the band gap narrowing caused by heavy doping aregained. Second, the hole concentration ionized by impurities is modified fromnondegeneracy to degeneracy. Third, the effect of conduction band effective states, theeffect of valence band effective states the effect of gap narrowing caused by doping and Gefraction and the effect of the impurities to the built-in electric field are consideredtogether. Especially, the effect of conduction band effective states to the built-in electricfield is considered for the first time. The results which we obtained are compared withothers.they are in agreement with each other.