Superlattice excitons and optical absorption

A formalism based on the superlattice crystal coordinate representation, which is valid for arbitrary well and barrier widths, is developed and applied to the Wannier exciton problem. A simple model for the electron-hole Coulomb interaction within the independent subband approximation permits nonvariational calculation of exciton binding energies, oscillator strengths, and optical absorption of both bound and continuum exciton states. The effects of growth axis directed electric and magnetic fields are emphasized. Numerical results for GaAs/ Ga1−xAlxAs and In1−xGaxAs/GaAs exciton binding energies and oscillator strengths as functions of well width, barrier width, and electric and magnetic field strengths show excellent agreement with experiment.