Room Temperature Stark-Ladder Transitions in GaAs/AlAs Superlattices with Different Miniband Widths

Abstract
We have studied room temperature Stark-ladder transitions in GaAs/AlAs superlattices with different miniband widths. Measured dependence of field-induced energy shifts of the Stark-ladder transitions on superlattice period agrees with theory. We have also shown dependence of quantum coherence on superlattice parameters, and observed the highest quantum coherence of 11 periods in the wide-miniband superlattice. These results give clear evidence that Wannier-Stark localization occurs over a wide range of miniband widths, and that is responsible for a negative differential conductivity mechanism.