Effects of rapid thermal annealing on the optical properties of In0.53Ga0.47As/In0.52Al0.48As multiple quantum wells with InGaAs and dielectric capping layers

Abstract

We investigated the effects of InGaAs and dielectric (SiO2 and Si3N4) capping layers on the intermixing behavior of InGaAs/InAlAs multiple quantum wells (MQWs) after rapid thermal annealing (RTA). With a fixed RTA time of 45 s, no appreciable shift of photoluminescence (PL) peak energy was observed in the samples annealed up to 800 and 850 °C for the SiO2- and Si3N4-capped MQWs, respectively. But they exhibited a significant improvement of PL intensity without a broadening of the PL spectra after the RTA. After an RTA at 900 °C for 45 s, a blueshift of 17 meV and a redshift of 25 meV were observed for the SiO2- and Si3N4-capped MQWs, respectively. Microstructures of the InGaAs/InAlAs MQWs observed by cross-sectional transmission electron microscopy before and after RTA reveal that the above improvement of PL intensity is associated with the curing of nonradiative recombination centers in the course of the relaxation of vertical composition modulation along the growth direction in the InGaAs well and the InAlAs barrier layers. The influence of dielectric and InGaAs cap layers on the improvement of PL intensity is explained by the ease of the cation and anion vacancy diffusion from the dielectric layers and through the InGaAs cap layer.