In this research, we experimentally investigated the photoluminescence (PL) spectra of an undoped GaAs/Al0.36Ga0.64As Tunnel-Coupled Quantum Well (TCQW) at 300 K and 77 K. At 300 K, PL spectra were broadened at various laser intensities due to the characteristic quantum-confinement electron levels in the active region of the TCQW during pumping excitation. At 77 K, at selected excitation intensities, the high-energy tails in the PL spectra of the studied structure corresponded with hot electron temperatures as functions of the energy of emitted photons. The average scattering energy rate of hot electrons in the system was also studied at a lattice temperature of 77 K. The average scattering energy rate of hot electrons obtained from this experimental study was in agreement with the calculated theoretical value.

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In this research, we theoretically investigated the exciton binding energies as a function of QW widths with the variation of the percent alloy contents. For any certain percent of alloy contents, the exciton binding energies increase proportionally with the increasing of QW widths. We also simulated the exciton binding energies as a function of the percent alloy contents of AlxGa1-xAs barrier with the variation of QW widths. For the narrower QW widths, with any certain percent of alloy contents, the exciton binding energies show higher discrete energy characteristic compared with the wider well widths. These results can explain the intersubband transition with MIR and Far-IR emission between donor doped levels in conduction band.