Influence of nitride and oxide cap layers upon the annealing of 1.3 µm GaInNAs/GaAs quantum wells

Effects of thermal annealing on optical and structural properties of GaInNAs/GaAs quantum well (QW) heterostructures, which were coated with dielectric films, were studied using photoluminescence, x-ray diffraction (XRD), and secondary-ion mass spectrometry (SIMS). A sample having no dielectric coating exhibited a rapid saturable blueshift in the beginning of annealing. A Si₃N₄ cap layer prevented the line shift, while a SiO₂ cap enhanced the shift. The XRD and SIMS spectra provided evidence that the large blueshift for the SiO₂-capped sample originated from Ga/In interdiffusion across the QW walls, and from a local reorganization of N-bonding configuration within the QW. The inhibition of blueshift for the Si₃N₄-capped sample was likely due to an improved stability of Ga–N bonds during annealing.