Wannier–Stark effect in strongly coupled three quantum well structures and superlattices

The Wannier–Stark effect has been investigated in strongly coupled three quantum well structures and 23.5 period superlattices consisting of 25 Å wide GaAs wells separated by Al0.25Ga0.75As barriers of the same width. A blue shift associated with the Wannier–Stark localization of heavy holes states is observed for the first time, followed by a second blue shift at higher electric fields due to the electron localization. This is contrary to the widely reported single blue shift of the order of (Δe+Δhh)/2, where Δe and Δhh are the electron and heavy hole miniband widths respectively, produced by Wannier–Stark localization in superlattices.