Field-induced delocalization and Zener breakdown in semiconductor superlattices

We investigate the electronic structure in strongly coupled superlattices o ver a wide held range. It is shown that the Wannier-Stark localization is f ollowed by a held-induced delocalization which is due to a strong Zener cou pling to continuum states. The associated Zener breakdown is quantitatively shown in a detailed analysis of the absorption. A comprehensive theoretica l model excellently describes the experimental results. Zener tunneling tim es are directly addressed with the help of time-resolved experiments. (C) 1 999 Published by Elsevier Science B.V. All rights reserved.