We employ a picosecond–time-resolved Raman-scattering technique to investigate the dynamics of two-dimensional electron-hole plasma confined to a multiple–quantum-well structure composed of layers of GaAs and (GaAl)As. The lifetime and the intersubband scattering time of the electrons photoexcited on the lowest electronic subbands are determined separately. Calculation of the rate of intersubband scattering by longitudinal-acoustical phonons successfully accounts for the observation of relatively long-lived electrons on the second subband of a 215-Å multiple–quantum-well structure.

• Received 10 September 1986

DOI:https://doi.org/10.1103/PhysRevLett.59.696