Emission spectra of terahertz quantum cascade laser

We calculated energy levels, wave functions, and energies of radiative transitions in terahertz quantum cascade lasers based on GaAs/Al0.15Ga0.85As heterostructures. Current-voltage characteristics and current dependences of laser radiation intensity were measured, and the maximum operating temperatures reaching 85 K were determined. Radiation spectra of quantum cascade lasers were measured for different temperatures, and the effect of intensity “pumping” from lowfrequency modes to high-frequency modes was found to happen in the case of an increase in the current and time delay of the signal capture, which is explained by heating of the sample during a pulse of the current. Application of the lasers for registration of impurity photoconductivity signals in semiconductor heterostructures was demonstrated

Emission spectra of terahertz quantum cascade laser

We calculated energy levels, wave functions, and energies of radiative transitions in terahertz quantum cascade lasers based on GaAs/Al0.15Ga0.85As heterostructures. Current-voltage characteristics and current dependences of laser radiation intensity were measured, and the maximum operating temperatures reaching 85 K were determined. Radiation spectra of quantum cascade lasers were measured for different temperatures, and the effect of intensity “pumping” from lowfrequency modes to high-frequency modes was found to happen in the case of an increase in the current and time delay of the signal capture, which is explained by heating of the sample during a pulse of the current. Application of the lasers for registration of impurity photoconductivity signals in semiconductor heterostructures was demonstrated

Cyclotron resonance and interband optical transitions in HgTe/CdTe(013) quantum well heterostructures

International audienceCyclotron resonance spectra of 2D electrons in HgTe/CdxHg1−xTe (0 1 3) quantum well (QW) heterostructures with inverted band structure have been thoroughly studied in quasiclassical magnetic fields versus the electron concentration varied using the persistent photoconductivity effect. The cyclotron mass is shown to increase with QW width in contrast to QWs with normal band structure. The measured values of cyclotron mass are shown to be systematically less than those calculated using the 8 × 8 Kane model with conventional set of HgTe and CdTe material parameters. In quantizing pulsed magnetic fields (Landau level filling factor less than unity) up to 45 T, both intraband (CR) and interband magnetoabsorption have been studied at radiation wavelengths 14.8 and 11.4 µm for the first time. The results obtained are compared with the allowed transition energies between Landau levels in the valence and conduction bands calculated within the same model, the calculated energies being again systematically less (by 3-14%) than the observed optical transition energies