Comparative study of the effect of an electric field on the photocurrent and photoluminescence of GaAs-GaAlAs quantum wells

The effects of an electric field on the excitons in GaAs-GaAlAs quantum-well heterostructures have been studied by means of low-temperature photoluminescence and photocurrent spectroscopy. Increasing the electric field causes a red shift of the excitonic luminescence to energies well below the bulk GaAs band edge, and a corresponding decrease of the total luminescence efficiency. We find very good agreement between the energy thresholds obtained by luminescence and photocurrent measurements. A significant shift of the luminescence relative to the photocurrent is observed at high fields as a result of enhanced bound-exciton luminescence when electrons and holes move closer to the interfaces.