Improved concepts for predicting the electrical behavior of bipolar structures in silicon

Attention is given to physically correct concepts for bipolar device modeling and to their application to Si bipolar transistors. These concepts use the perturbed densities of states and nonparabolic bands which arise from a quantum mechanical description of bandgap narrowing, in order to separately compute effective intrinsic carrier concentration and carrier mobility. They also use minority carrier lifetimes which agree much better with measured lifetimes in processed silicon, and employ Fermi-Dirac statistics. When these concepts are incorporated into a device analysis code, and then used to compute the DC common-emitter gain of two p-n-p transistors, the predicted gains agree with those measured. These concepts also offer potential improvements in predicting the gain's temperature dependence.