Carrier drift, diffusion, and thermionic emission for classical semico
nductor devices (p-n junctions, heterostructures, etc.) is most easily
described using expressions derived from a Boltzmann transport equati
on point of view. This point of view is not particularly applicable to
quantum-well transport. It is shown here that by postulating a region
of phase space that is forbidden to the mobile carriers and then alte
ring the scattering probability so that no particles are scattered to
the forbidden region, a Boltzmann-equation-based formalism emerges tha
t can describe the mobile-carrier component of quantum-well transport.