A note on heterojunction discontinuities

Recently, an analytic proof has been advanced to the effect that the intrinsic Fermi level of a heterojuntion is by necessity continuous across the interface joining two different semiconductors. Here we wish to show that the proof given is incorrect and that the solution of Poisson´s equation for an intrinsic heterojunction on which the proof was based, does not yield any information on possible continuities or discontinuities of the intrinsic Fermi level.