INTER-MINIBAND OPTICAL-ABSORPTION IN A MODULATION-DOPED ALXGA1-XAS/GAAS SUPERLATTICE

Theoretical calculations of the optical absorption between the conduction subbands in a modulation-doped Al(x)Ga(1-x)As-GaAs superlattice are presented. The electronic subband structures, including both the couplings between different quantum wells and the band bending due to screening effects, are calculated self-consistently by solving simultaneously the Schrodinger and the Poisson equation. Linear intersubband absorption in the superlattice is then calculated and the absorption spectra show interesting line shapes which reflect the joint density of states between different subbands. The dependence of the absorption (energy-band width, resonant absorption energy, and magnitude of peak absorption coefficient) on device parameters such as doping concentration, well width, barrier width, and aluminum mole fraction in the barrier, which are useful for the design of infrared detectors, is also investigated. These theoretical results are also compared with experimental data.