Abstract
In the present work we report the first measurement of intersubband lifetimes in Si/Si
Ge
quantum well samples. We have determined T
by a time resolved pump and probe experiment using the far infrared picosecond free electron laser source FELIX at Rijnhuizen, the Netherlands. In a sample with a well width of 50 Å and a sheet density of 2.1 × 10
cm
we find a lifetime of 30 ps while 20 ps is observed for a density of 1.1 × 10
cm
and a well width of 75 Å. We discuss acoustic phonon, as well as optical phonon intersubband scattering as possible limiting processes for the observed lifetimes in Si/SiGe and GaAs/AlGaAs quantum wells.