The behaviour of optical and structural properties of GaInNAs/GaAs quantum wells upon annealing

Our experiments show that photoluminescence spectra from dilute nitride Ga_1-xIn_xN_yAs_1-y/GaAs (y < 2%) quantum wells (QW) are independent of growth temperature of the QWs in the range from 430 to 470°C. Spectral blue shift upon annealing is large for the low-temperature QW (430°C), and emission intensity is more enhanced than that of the high-temperature QW (470°C). Raman scattering reveals that the 430°C QW contains more In-N bonds than does the 470°C QW. It seems, therefore, that the blue shift, which is proportional to a number of In-N bonds, originates from the presence of point-like defects of the alloy. Lower emission intensity from the annealed 470°C sample may be attributed to more pronounced alloy fluctuations and interface roughening, seen in cross-sectional transmission electron micrographs.