Thermal treatment of InGaAs/GaAS self-assembled quantaum dots with SiNx and SiO2 capping layers

초록

there has been considerable interest in the growth of self-assembled quantum dots (SAQDs) due to their fundermental physics of 3-dimensional quantum confinement together with the novel device functionality that they can provide [1]. The optical properties of SAQDs are important for their application to optical devices such as laser diodes (LDs). The optical properties of SAQDs are dependent not only on the growth condition but also on the post-growth process such as athermal treatment[2]. In this study, we have studied the thermal treatment effect on the optical properties of InGaAs/GaAs SAQDs in order to improve their quality. The thermal treatment of InGaAs/GaAs SAQD structure, which was grown by metal organic chemical vapor deposition (MOCVD), have been carried out at 700℃ with SiO2 and SiNx capping by varying annealing time from 1 to 4 minutes under the N2-gas ambient. It has been confirmed, from the photoluminescence(PL) measurement after the thermal treatment, that the emission peak of SAQDs was blue-shifted up to 190 meV, the full width at half maximum(FWHM) was narrowed from 76 meV to 47 meV and the PL intensities were increased. The SiNx-SiO2 doubled capping layer has been also found to induce larger increase in PL intensity and better carrier confinement after thermal treatment SAQDs compared to the SiO2 single capping layer.