Acceptor-related infrared optical absorption in GaAs/AlGaAs quantum wells
The results of the theoretical and experimental investigations of optical response of the acceptor centers in narrow GaAs/AlGaAs quantum wells in the infrared spectral range are presented. In the theoretical part, we focused on the probabilities of the photoionization of acceptor centers taking into account the complicated valence band structure and intermixing the light and heavy hole states. We used the finite-difference method to quantize the Luttinger-Kohn Hamiltonian and the decomposition of the impurity potential over the eigenstates of this Hamiltonian with the quantum well profile to obtain the acceptor state energies and wavefunctions in momentum space. The momentum-dependent decomposition coefficients were used to calculate the optical matrix elements of the hole transitions from localized acceptor states to 2D continuum states in dipole approximation. Calculated spectral and polarization dependencies of the infrared optical absorption due to photoionization of acceptors are discussed. Equilibrium absorption spectra of the polarized infrared radiation were measured in a wide temperature range. Spectral positions of the observed absorption peaks are in satisfactory agreement with theoretical calculations.