“…The equations of the QHD model are obtained by adding quantum correction terms to the equations of the classical hydrodynamic model for semiconductors. On the derivation of QHD models see [3,4,5,6] and references therein. Denoting by n, J, V , p, C the electron density, electron current density, electric potential, pressure and doping profile of the semiconductor, the equations of the isothermal (p(n) = n) or isentropic (p(n) = n α , α > 1) QHD model read n t + div J = 0,…”