Theoretical analysis of intersubband optical absorption in GaAs/AlGaAs quantum wells: influence of well width and dephasing energy

Abstract

This study presents a simulation of the optical absorption spectra within the THz frequency region using Matlab, considering a doping concentration of N=1×1040 cm⁻³. Quantum well (QW) widths of 25 nm, 30 nm, 35 nm, and 40 nm were analyzed, with results depicted in Figures 11 through 14, respectively. The simulations incorporate varying dephasing energies Γ of 8 meV, 12 meV, and 16 meV to account for broadening mechanisms such as phonon interactions, impurity scattering, and other dephasing processes. A clear redshift in the absorption edge is observed with increasing QW width, as evidenced in results, indicating that wider wells accommodate lower energy confinement states. Additionally, the absorption peaks become sharper as the QW width increases, consistent. The dephasing energy significantly influences the spectral line shape; higher Γ values result in broader absorption features with diminished peak intensity, reflecting increased scattering and reduced electronic coherence. Conversely, lower Γ (8 meV) yields sharper peaks, aligning with previous experimental research by scholars. These results underscore the critical role of QW dimensions and dephasing mechanisms in tailoring the optical properties of quantum wells, which is essential for optimizing THz optoelectronic devices.