We consider a one–dimensional coupled stationary Schrödinger drift–diffusion model for quantum
semiconductor device simulations. The device domain is decomposed into a part with large quantum
effects (quantum zone) and a part where quantum effects are negligible (classical zone). We give
boundary conditions at the classic–quantum interface which are current preserving. Collisions within
the quantum zone are introduced via a Pauli master equation. To illustrate the validity we apply the
model to three resonant tunneling diodes