Study of Single-Electron Spectrum of GaAs/AlGaAs Heterostructure for Mid-IR Photodetectors via Low-Temperature Luminescence

By measuring low-temperature photoluminescence, we demonstrated the role of interface blurring and the introduction of background impurities in the formation of the single-electron spectrum of GaAs/AlxGa1–xAs quantum well heterostructures used to fabricate mid-IR photodetectors. Background impurities, having a noticeable effect on the emission spectrum of quantum wells, do not affect their absorption spectra (luminescence excitation). Nevertheless, the blurring of the interface distorts the structure of single-electron states significantly, while weakly manifesting itself in luminescence. We proposed a method for estimating the degree of blurring of quantum well interfaces for photodetectors by the spectra of excitation of their exciton luminescence.