Study of the low-temperature line broadening mechanisms for excitonic transitions in GaAs/AlGaAs modulator structures

Abstract

We examine the dominant line broadening mechanisms for excitonic lines in a quantum well in the presence of strong transverse electric fields. We have calculated the line broadening due to interface roughness effects and lifetime broadening effects. We find that the line broadening effects due to interface roughness increase rapidly as the transverse electric field is increased and for a 100‐Å Al_0.3Ga_0.7As/GaAs well, increase by a factor of ∼2.0 as the field is increased from 0 to 100 kV/cm. The broadening due to lifetime effects is very sensitive to the band lineup assumed and is much smaller than interface roughness effects even for one monolayer interface roughness.