Relaxation dynamics of electrons between Landau levels in GaAs.

Abstract

The relaxation dynamics of free electrons between Landau levels is traced on a picosecond time scale via the time evolution of the band-to-acceptor luminescence in $p$-type GaAs after resonant excitation of the $n=1$ Landau level. For electron densities $N>{10}^{14}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, relaxation occurs via electron-electron scattering with a $\frac{1}{e}$ decay time of 7.5\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ps ${\mathrm{cm}}^{\ensuremath{-}3}$/N. For lower electron densities, relaxation becomes independent of density due to elastic impurity scattering.