Optical-interband-absorption experiments are performed on GaAs doping superlattices, which have sawtooth-shaped band-edge potentials. Absorption spectra reveal for the first time a clear signature of quantum-confined transitions and exhibit excitonic enhancement of the absorption. The maxima in the experimental absorption spectra are assigned to theoretical energies of quantum-confined transitions with very good agreement. The observation of quantum-confined transitions demonstrates the superiority of the new sawtooth structure over conventional doping superlattices.

• Received 10 June 1988

DOI:https://doi.org/10.1103/PhysRevB.38.8305