Effect of electric field, both external and built-in, on GaAs-AlAs structures

Experimental results on GaAs-AlAs multiple quantum wells where the confined electron level is initially delocalized due to the mixing between the (Gamma) and X levels are presented. The applied electric field reduces this coupling and reconfines the electron in the GaAs layer. This causes an increase in oscillator strength and a blue shift of the heavy hole to (Gamma) - electron transition. Reduction of the charge transfer from narrow wells to a wide well has also been observed.