Ultrasensitive electroabsorption due to Wannier–Stark localization in extremely shallow superlattices at 77 K

Abstract

We have observed Wannier–Stark localization in extremely shallow superlattices (SL) at 77 K, which results in a quasi‐blue shift of the absorption edge at very small electric fields. The formation of a Stark ladder is also clearly shown. The blue shift results in a change in absorption coefficient from 1.7 μm⁻¹ (at 0.2 V/μm) to 0.98 μm⁻¹ (at 0.6 V/μm) for a GaAs/Al_0.07Ga_0.93As SL; for a GaAs/Al_0.02Ga_0.98As SL we obtain a change from 2.1 μm⁻¹ (at 1.1 V/μm) to 0.9 μm⁻¹ (at 1.5 V/μm).