Intraband Optical Absorption in Type-II GaAsSb/InGaAs DQW Heterostructure for Detection of Low Energetic Radiations

The studies made in this article are directed toward the calculations accomplished for the evaluation and improvement of the performance of type-II GaAsSb/InGaAs DQW (double quantum well) heterostructure for detection of weak and low energetic radiations. The k.p technique considering the intraband transitions was used to investigate the performance of the heterostructure in context of dipole and momentum matrix elements followed by partial and total optical absorption spectra. The calculation results suggest that the radiations having energy ~150 meV can easily be detected by photodetectors comprising such QW heterostructures. It has also been proved that the performance in terms of optical absorption is improved with the red shift when the applied DC field on the heterostructure is increased. In the optical spectra, the two separate absorption peaks were evident: the first, centered around ~85 meV, corresponds to transitions between quantized hole subbands (h1→h2) in the valence band, indicating strong intraband coupling among hole states. While, the second peak, appearing near ~145 meV, is attributed to transitions among electron subbands (e1→e2 and e1→e3) in the conduction band. The clear separation between these two distinct peaks signifies well-defined energy level spacing in both bands, a characteristic feature of optimized QW heterostructure enhancing intersubband transition efficiency. Thus, it can be concluded that the designed InGaAs/GaAsSb QW heterostructure can detect weak and low energy radiations in the range of (~75 meV to 150 meV) via capturing the intraband transitions with the enhanced optical absorption characteristics. These findings demonstrate the potential of InGaAs/GaAsSb QW heterostructures for mid-infrared photodetection applications.