Evidence of formation of an XL miniband in short-period type-II GaAs/AlAs superlattices

The vertical magnetoresistance was explored in short-period doped GaAs/AlAs superlattices. The effect of the vertical-longitudinal magnetoresistance expected to occur in the case of the open Fermi surface was found. The analysis of the possible position of the Fermi level allowed us to distinguish the type of the lowest miniband-between Gamma and X origins. Our results indicate that the lowest miniband is formed by the X-L electron states of GaAs and AlAs. The result agrees with the theoretical predictions and shows that the residual stress does not significantly influence the miniband structure of the short-period superlattices studied.