Influence of Fröhlich Interaction on Intersubband Transitions of InGaAs/InAlAs-Based Quantum Cascade Detector Structures Investigated by Infrared Modulated Photoluminescence

We demonstrate the use of an infrared modulated photoluminescence (PL) method based on a step-scan Fourier-transform infrared spectrometer to analyze intersubband transition (ISBT) of InGaAs/InAlAs quantum cascade detector (QCD) structures. By configuring oblique and parallel excitation geometries, high signal-to-noise ratio PL spectra in near-to-far-infrared region are measured. With support from numerical calculations based on the k ⋅ p perturbation theory, the spectra is attributed to intraband and interband transitions of InGaAs/InAlAs QCD structures. Temperature evolution results show that the k-dependent transitions caused by longitudinal optical phonon-assisted scattering (Fröhlich interaction) plays an important role in the ISBT. These results suggest that this infrared modulated-PL method has great potential in characterizing QCD devices and conducting performance diagnostics.