Measurements of band gap narrowing in heavily doped epitaxial emitters and the modeling of heavily doped silicon

A new method is described for the measurement of band gap narrowing in heavily doped epitaxial emitters of bipolar transmitters. The principal advantages of this method are that very heavily doped silicon (∼ 10²⁰cm^-3) can be used and that lifetime corrections can be independently measured on the same devices. The inclusion of band gap narrowing in device modeling is considered. It is shown that experimental values of band gap narrowing as generally reported can be easily included in the classical (Boltzmann) transport equations using an effective field term without additional Fermi-Dirac connections. Such a model is valid in low injection which is usually the case for the heavily doped regions of devices.