In the above problem, we found that the drift current due to either charge carrier can be approximated by jdrift = en/4, where n is the density of the conduction electrons on the p-side, or of the holes on the n-side. We are now going to apply this to a typical p-n junction in a semiconductor at 300 K with a band gap of 1.1 eV and a band displacement across the junction of 0.6 eV. The Fermi level lies 0.25 eV below the conduction band on the n-side.
(a) What is the density of conduction electrons on the p-side of the junction?
(b) What is the density of valence holes on the n-side of the junction?
(c) What is the average thermal speed of a conduction electron or hole (use m∗ = m for both)?
(d) From this information, estimate the drift current density, jdrift, across the junction.