The effects of collector profile on the reverse biased second breakdown is analytically analyzed. Three types of collector profile that are mostly using in the industry are analyzed in detail. First one is the collector having a single epitaxial layer, second is the collector that has a double epitaxial layer with a buffer layer, and third is the collector having a diffused profile. Electric field distributions in the collector region are calculated analytically for several operating current densities for a given collector-emitter reverse biased voltage that shows good agreement with the numerical simulation results. Critical electric field that corresponds to the onset of avalanche multiplication process is calculated by using simple approximated equation suggested by W.Fulop[15]. Then the critical current densities corresponding to the onset of the reverse biased second breakdown are calculated analytically and compared for three types of collector profile. Critical voltages for a given current density are also calculated analytically and are compared. Comparison with the numerical simulation results demonstrates the validity of our formulation. Finally, based on these formulations, several design curves are generated, which are very useful for the optimal power device design.
