Electron distribution among the $\Gamma $, L, and X GaAs conduction band valleys in an Fe/GaAs(n) Schottky barrier.*

The electroluminescence (EL) spectra from Fe/GaAs(n)/InGaAs/GaAs(p) spin-LEDs have a complicated composition. In addition to the $e_1 \ell_1 $light and $e_1 h_1 $ heavy hole excitonic features the band-edge EL contains the following phonon replicas: $e_1 h_1 -TA$, $e_1 \ell_1 -LO$, $e_1 h_1 -LO$, $e_1 h_1 -LO-TA$, and $e_1 h_1 -LO-LA$. The replicas are interpreted as due to recombination processes that involve electrons occupying the L and X valleys of the GaAs(n) conduction band. The high momentum electrons are promoted to the higher energy L and X valleys by the strong electric field at the Fe/semiconductor interface [1]. \newline [1] S. Saikin et al, J. Phys: Condens.Matter \textbf{18}, 1535, (2006)