Observation of Wannier-Stark localization in shallow superlattices

摘要

Surprisingly, the onset of superlattice (SL)-type electroabsorption (EA) (localization/delocalization and Stark ladder phenomena) as multi-quantum well (MQW) barriers are lowered does not correlate with miniband width. As the barriers of a 100/100 angstroms GaAs/Al$-x$/Ga$-$MIN@1$/As MQW are lowered to x $EQ 0.01, similar (quantum confined Stark effect) EA as for x $EQ 0.3 samples is seen. For x $EQ 0.02, as the MQW period (d) is shortened to 140 angstroms, SL-type EA is observed but does not correlate with miniband width. This shows that standard models do not apply for shallow systems. For x $EQ 0.07 and d $EQ 175 angstroms SL effects consistent with standard models are observed.