Exciton binding energies and oscillator strengths in a symmetric ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs double quantum well

Within the framework of the effective-mass approximation, we have used an improved three-parameter trial function to calculate the exciton binding energy for both the ground state and the excited states in a symmetric double quantum well. When comparing our results with those derived with the commonly used one-parameter trial function, we found that the binding energies are improved significantly, especially for the excited states. Our calculated exciton transition energies agree well with the measured photoluminescence-excitation (PLE) spectra. We have also calculated the oscillator strengths. By comparing our results with the oscillator strength derived from the PLE spectra, we find good agreement for heavy holes, but less satisfactory agreement for light holes.