Influence of (001) vicinal GaAs substrates on the optical properties of defects in low-temperature-grown GaAs/AlGaAs multiple quantum wells

摘要

Photoluminescence (PL) spectroscopy and carrier lifetime measurement has been used to characterize optical properties of defects in the low-temperature (LT) grown GaAs/AlGaAs multiple quantum well structures. Two sets of samples were grown at 400 degrees C by molecular beam epitaxy on nominal and miscut towards GaAs substrates, respectively. After growth, samples were subjected to 30 s rapid thermal annealing at 600-800 degrees C. It is found that after annealing, two defect-related PL features appear in the samples grown on miscut GaAs substrates, but not in those grown on nominal GaAs substrates. The carrier lifetimes are about 31 and 5 ps in as-grown on nominal and miscut GaAs substrates, respectively. Optical transient current spectroscopy show different types of deep levels and their dependence on the annealing temperature. We found larger excitonic electroabsorption and stronger photorefractive effect in samples grown on miscut substrates.