Time-resolved Raman measurements of intersubband relaxation in GaAs quantum wells

Abstract

We have measured the electron intersubband relaxation time due to the emission of longitudinal-optical (LO) phonons in GaAs-AlGaAs quantum wells using time-resolved anti-Stokes Raman scattering. When the energy separation of the subbands is greater than the LO phonon energy we find the lifetime of electrons in the n=2 level to be \ensuremath{\le}1 ps which is in excellent agreement with theoretical calculations of two-dimensional electron-phonon interactions.