INVESTIGATION OF L-RELATED INDIRECT TRANSITIONS IN GAAS GAALAS MULTIQUANTUM WELLS UNDER HYDROSTATIC-PRESSURE/

Intersubband transitions in GaAs/GaAlAs multiquantum wells (QW) under hydrostatic pressure have been investigated with photomodulated transm ission spectroscopy and free-standing QW samples. In addition to the d irect transitions associated with the Gamma critical points, several L -related transitions between the L conduction band and the Gamma valen ce band of the GaAlAs barriers and between the L conduction subbands a nd the Gamma valence subbands inside the GaAs quantum wells are observ ed. The distinct L-related spectral features are a clear indication th at photomodulated transmission is particularly useful for enhancement of the weak phonon-assisted indirect transitions. (C) 1997 American In stitute of Physics.