In artificial structures, such as superlattices, arbitrary relationships between band-structure parameters can be achieved, enforcing the need for a reinvestigation of the interband transition of a crystal electron originally studied by Zener. We report the existence of nonexponential corrections to the Zener tunneling rate and demonstrate their importance in parameter regimes relevant for quantum-transport properties of superlattices, such as Bloch oscillations. Oscillations in the I-V characteristic of a superlattice are predicted with periods determined by the band-structure parameters.

• Received 31 July 1991

DOI:https://doi.org/10.1103/PhysRevB.44.11494