Fast Light-Emitting Silicon-Germanium Nanostructures

Results obtained from photoluminescence (PL) measurements performed on Si/Si
$_{1\hbox{-}x}$
Ge
$_{x}$
nanostructures with a single Si
$_{1\hbox{-}x}$
Ge
$_{x}$
nanometer-thick layer (NL) incorporated into Si/Si
$_{0.6}$
Ge
$_{0.4}$
cluster multilayers (CMs) are reviewed. By employing depth-dependent pulsed laser excitation, the SiGe NL PL decay is found to be nearly a 1000 times faster compared to that in CM PL. A physical model taking into consideration the Si/SiGe hetero-interface composition is proposed to explain the fast and slow time-dependent recombination rates.