MBE growth of single crystalline AlInAs/GaInAs MQWs at the low growth temperature limit

Single crystalline AlInAs/GaInAs multiple quantum wells (MQWs) were grown by MBE at growth temperatures (Tg) ranging from 550 degrees C down to 100 degrees C. High structural quality was ascertained for all samples from X-ray diffraction (XRD) measurements. Room temperature (RT) photoluminescence (PL) signals were monitored down to Tg = 150 degrees C. With decreasing Tg a blueshift of the emission by 30 meV was observed, as also confirmed by RT absorption measurements. This blueshift is referred to two-dimensional (2D) band filling due to an increase of the residual free electron concentration of more than two orders of magnitude at low Tg which in turn is responsible for the significant weakening of excitonic features in the absorption spectra.