High-field magneto-spectroscopy of quasi-2D electrons and holes in InAs/Al xGa 1− xSb single quantum wells

Abstract

Far-infrared magneto-transmission studies on two high mobility InAs/Al x Ga 1− x Sb ( x=0.1 and 0.2) type-II single quantum wells in magnetic fields up to 30 T show that a magnetic-field-induced semimetal–semiconductor (SM–SC) transition occurs in the x=0.2 sample between 8 and 12 T, and in the x=0.1 sample in the vicinity of 28 T. The so-called X-lines vanish at high magnetic fields and temperatures, consistent with their assignment to internal transitions of stable, spatially separated excitons. A large splitting (∼30 cm −1) between cyclotron-resonance-like transitions for 13 T⩽ B⩽23 T for the x=0.1 sample is attributed to enhanced spin splitting due to conduction–valence-band Landau-level mixing across the interface.