SUPERLATTICE EXCITONS AND OPTICAL-ABSORPTION

A formalism based on the superlattice crystal coordinate representatio n, which is valid for arbitrary well and barrier widths, is developed and applied to the Wannier exciton problem. A simple model for the ele ctron-hole Coulomb interaction within the independent subband approxim ation permits nonvariational calculation of exciton binding energies, oscillator strengths, and optical absorption of both bound and continu um exciton states. The effects of growth axis directed electric and ma gnetic fields are emphasized. Numerical results for GaAs/Ga1-xAlxAs an d In1-xGaAs/GaAs exciton binding energies and oscillator strengths as functions of well width, barrier width, and electric and magnetic fiel d strengths show excellent agreement with experiment.