CHARGE-INJECTION THEORY OF BIPOLAR JUNCTION TRANSISTORS

A physical theory of the bipolar junction transistor which provides cl osed-form solutions for current/voltage relations for generalized bias conditions is introduced. Included are the new concepts of emitter an d collector collection efficiency. Both emitter and collector regions are treated symmetrically to allow for accurate treatment of operation in both the saturation region and the forward-active region, as well as the reverse-active region. There are six components each of emitter and collector current, resulting from inclusion of emitter injection efficiency, surface recombination at the pn junction peripheries, and bulk base recombination as well as finite minority-carrier collection efficiency. Direct comparison between theory and experiment over the e ntire transistor operating range from deep saturation where I(C) = 0 c ontinuously into the forward-active region where V(CE) is much greater than the thermal voltage V(T) shows excellent agreement.