Quantum Transport: The Link between Standard Approaches in Superlattices

Theories describing electrical transport in semiconductor superlattices can essentially be divided in three disjoint categories: (i) transport in a miniband; (ii) hopping between Wannier-Stark ladders; and (iii) sequential tunneling. We present a quantum transport model, based on nonequilibrium Green functions, which, in the appropriate limits, reproduces the three conventional theories and describes the transport in the previously inaccessible region of the parameter space.