Quantum kinetic equations for describing transport in submicron semiconducting devices in the finite collision duration regime are developed which are nonlocal in time and momentum. Utilizing a projected self-scattering formulation, a retarded path-integral equation is obtained. Quantum kinetic equations are usually exceedingly difficult to solve. The formulation found here presents a powerful technique to achieve these solutions even in the case where nonlocal effects are important.

• Received 19 December 1978

DOI:https://doi.org/10.1103/PhysRevLett.42.1779