Wigner-function formalism applied to semiconductor quantum devices: Failure of the conventional boundary-condition scheme

摘要

The Wigner-function formalism is a well known approach to model chargetransport in semiconductor nanodevices. Primary goal of the present article isto point out and explain intrinsic limitations of the conventionalquantum-device modeling based on such Wigner-function paradigm, providing adefinite answer to open questions related to the application of theconventional spatial boundary-condition scheme to the Wigner transportequation. Our analysis shows that (i) in the absence of energy dissipation(coherent limit) the solution of the Wigner equation equipped with givenboundary conditions is not unique, and (ii) when decoherence/dissipationphenomena are taken into account via a relaxation-time approximation thesolution, although unique, is not necessarily a physical Wigner function.