INJECTION CURRENT IN A PLANAR-DOPED BASE SI BIPOLAR JUNCTION TRANSISTOR

This work investigates electron transport in n-i-deltap-i-n Si transis tor structures by using thermionic theory. Self-consistent solutions o f the Schrodinger and Poisson equation reveal that in these structures the potential barrier for electrons exhibits a narrow cusp which stem s from the finite vertical extension of the two-dimensional hole gas i n the planar doped base. As the width of the cusp amounts to be few nm only, significant electron tunneling occurs, resulting in thermionic field emission currents that exceed thermionic emission currents even at room temperature. As a further consequence a planar doped base orie nted in a (001) plane acts as a mass filter that blocks heavy effectiv e mass electrons occupying the two-fold degenerated valleys that are a ligned perpendicularly to the planar doped base.