Impurity free vacancy disordering of self-assembled InGaAs quantum dots by using PECVD-grown SiO2 and SiNx capping films

Abstract

Impurity free vacancy disordering (IFVD) of InGaAs self-assembled quantum dots (SAQDs) grown by metal organic chemical vapor deposition (MOCVD) method has been carried out at 700 degreesC for the time range from 1 min to 4 min by using SiO2 and SiNx-SiO2 dielectric capping layers. The photolummescence (PL) peak was blue shifted up to 157 meV and its full width at half maximum (FWHM) was narrowed from 76 meV to 47 meV as the annealing time increased. The integrated PL intensity was increased after the thermal annealing, which may be attributed to a defect quenching. There was an optimum annealing condition to get the largest integrated PL intensity for each dielectric capping. SiNx-SiO2 double capping layers have been found to induce larger integrated PL intensity and better carrier confinement after the thermal annealing of SAQDs compared to SiO2 single capping layer, even though SiNx-SiO2 double capping induced larger blue-shift than SiO2 single capping.