Hole Spin-Relaxation in Quantum Wells from Saturation of Inter-Subband Absorption

Spin-sensitive saturation of absorption of infrared radiation has been investigated in p-type GaAs QWs. It is shown that the absorption saturation of circularly polarized radiation is mostly controlled by the spin relaxation time of the holes. The saturation behavior has been investigated for di:erent QW widths and in dependence on the temperature with the result that the saturation intensity substantially decreases with smaller QW width. Spin relaxation times were experimentally obtained by making use of calculated (linear) absorption coe;cients for inter-subband transitions. The question of selection rules for intersubband transitions between hole subbands is addressed

Temperature shift of intraband absorption peak in tunnel-coupled QW structure

An experimental study of the intersubband light absorption by the 100-period GaAs/Al0.25Ga0.75As double quantum well heterostructure doped with silicon is reported and interpreted. Small temperature redshift of the 1–3 intersubband absorption peak is detected. Numerical calculations of the absorption coefficient including self-consistent Hartree calculations of the bottom of the conduction band show good agreement with the observed phenomena. The temperature dependence of energy gap of the material and the depolarization shift should be accounted for to explain the shift. © 2017 Elsevier B.V

Terahertz luminescence in strained GaAsN:Be layers under strong electric fields

The authors report on the experimental studies of terahertz emission from strained GaAsN/GaAs microstructures doped with beryllium at the conditions of electric breakdown of the shallow impurity. The terahertz emission spectrum demonstrates several distinctive signatures that are related to spontaneous optical transitions between resonant and localized states of the acceptor. The energy spectrum calculated for the Be acceptor in the GaAsN/GaAs heterostructure fits reasonably well with the experimentally observed peaks