Impact ionization of free and bound excitons in AlGaAs/GaAs quantum wells

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Abstract
The authors present a study of the effect of a parallel electric field on the excitonic photoluminescence (PL) from AlGaAs/n-GaAs quantum wells (QWs). They observe sharp thresholds in the quenching of luminescence from free and bound excitons at fields near a few tens of V cm-1. PL lifetime measurements of the excitons show that the recombination lifetime is unaffected during the quenching. The mechanism responsible for the observed effects is shown to be due to impact ionization of the excitons by the free carriers heated in the electric field.