Lateral transport and far-infrared radiation of electrons in In x Ga1 − x As/GaAs heterostructures with the double tunnel-coupled quantum wells in a high electric field

Abstract

It is shown that the far-infrared radiation of electrons in the selectively doped heterostructures with double tunnel-coupled quantum wells in high lateral electric fields strongly depends on the level of doping of the wells. At a high impurity concentration in a narrow well, higher than (1−2) × 1011 cm−2, the radiation is caused only by indirect intrasubband electron transitions. At a lower concentration, along with the indirect transitions, the direct intersubband transitions also contribute to the radiation. These transitions become possible in high electric fields due to the real-space electron transfer between the quantum wells.