Photoluminescence and AFM studies on blue shifted InAs/AlyGa1-yAs quantum dots

Photoluminescence and structural properties of self-assembled InAs quantum dots, grown on AlyGa1-yAs, are studied for y = 0, 0.3, and 0.5. A maximum b lue shift of 150 meV for the ground state: emission energy is determined wi th increasing y for the samples as grown, Increased surface density and siz e inhomogeneity is observed for growth on AlGaAs compared to growth on GaAs . Rapid thermal annealing at temperatures ranging from 550 to 850 degreesC is used to further increase the ground state emission energy with respect t o the as grown samples. We find a shift up to a maximum emission energy of 1.9 eV for InAs quantum dots (QDs) embedded in Al0.3Ga0.7As compared to 1.4 eV for GaAs matrix material. To combine the higher spectral shift by annea ling for InAs QDs embedded in AlGaAs with the lower dot density for the gro wth on GaAs, favored for single dot spectroscopy, we investigated InAs QDs grown on AlGaAs separated by 2 ML GaAs. For these samples we observe a maxi mum shift by annealing up 1.4 eV and intense room temperature PL.