Thermal annealing effect on 1.3-μm GaInNAs/GaAs quantum well structures capped with dielectric films

Abstract

Two kinds of dielectric films, Si3N4 and SiO2, deposited onto the surface of 1.3-μm GaInNAs/GaAs quantum well (QW) structures were studied upon post-growth thermal annealing. The blue-shift in photoluminescence (PL) as a function of annealing time showed distinct dependence on the selection of the dielectric films. It was found that a Si3N4 cap layer inhibits the blue-shift under specific annealing conditions and the blue-shift inhibition effect increases with the thickness of the Si3N4 cap; while a SiO2 cap layer enhances the PL blue-shift. X-ray diffraction (XRD) and secondary-ion-mass-spectrometry (SIMS) indicated that the enhanced blue-shift in PL from the SiO2-capped sample was caused by two factors: interdiffusion of Ga and In atoms across the QW interfaces and the decrease of N–Ga ion density (and hence N) in the QW material. Compared with the SiO2 caps, Si3N4 cap layers can inhibit both of these factors. Time-resolved PL decay measurements at room temperature were performed to study the optical properties of the uncovered and Si3N4-capped samples.