Abstract

Femtosecond spectroscopy of electron and hole populations performed in semiconductors gives important information on the mechanisms that lead to the primary steps of energy relaxation in these materials. ¹ For instance, the ultrafast dynamics of a hole burning, created in the continuum of states well above the band gap, has been investigated in bulk GaAs (Ref. 2) and GaAs/ GaAlAs quantum wells (Ref. 3) with the pump-probe technique. These experiments allowed the direct measurement of the thermalization of the hot-carrier populations induced by the ultrashort pump pulse. In this type of experiment, the measured relaxation time is a combination of both the electron and hole thermalization processes, which, in fact, can be very different because of the different values of k, the dispersion of the valence and conduction bands. This drawback is inherent to the technique itself where both populations are simultaneously probed.

© 1994 Optical Society of America