Abstract
The electroluminescence (EL) spectra from $\mathrm{Fe}∕\mathrm{Al}\mathrm{Ga}\mathrm{As}(n)∕\mathrm{Ga}\mathrm{As}∕\mathrm{Al}\mathrm{Ga}\mathrm{As}(p)$ spin LEDs contain an ${e}_{1}{h}_{1}$ excitonic feature; in addition, they exhibit new features not present in the photoluminescence (PL) spectra, that are ``satellites'' or ``replicas'' of the exciton. These satellites are red shifted with respect to ${e}_{1}{h}_{1}$ by energies that are approximately equal to those of zone edge phonons in GaAs. The intensity of the replicas depends strongly on bias voltage. In the presence of a magnetic field the satellites become circularly polarized as ${\ensuremath{\sigma}}_{+}$ but their polarization is always lower than that of ${e}_{1}{h}_{1}$. The satellites are interpreted as due to recombination processes that involve zone edge electrons that tunnel into the GaAs quantum well. These processes occur simultaneously with the emission of zone-edge phonons. Our interpretation is supported by a numerical simulation of the properties of electrons tunneling through an $\mathrm{Fe}∕\mathrm{Ga}\mathrm{As}(n)$ Schottky barrier.
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