Presentation Information
[17p-W8E_307-2]Influence of Mid-Cap Annealing on the Photoluminescence of InAs Quantum Dots on GaAs(001)
〇(P)Rhenish Simon1, Kazuki Koyama1, Ronel Christian Roca1, Itaru Kamiya1 (1.Toyota Tech. Inst.)
Keywords:
Quantum Dots,MBE,In-Flush
InAs quantum dots (QDs) offer tunable emission for laser and sensor applications. GaAs capping is typically done to protect the QD, however it induces strain and In-Ga intermixing leading to a PL blueshift. While initial capping (IC) and mid-cap annealing (In-flush) are used to control QD structure, a systematic understanding of the growth dynamics is needed to discriminate natural intermixing from thermally driven shrinking. In this work, we investigate these dynamics via PL emission and AFM. Samples were grown via MBE: 2.0 ML InAs QDs on GaAs grown at 500°C with an InGaAs initial cap (IC) and GaAs finishing cap (10 nm total cap thickness). The "Flush" samples included a 5-minute annealing step at 540°C before the deposition of finishing cap. AFM of the uncapped sample reveals an average QD height below 8 nm. PL spectra show that the purely GaAs-capped samples has the largest blueshift due to intermixing. While the InGaAs IC reduces this shrinkage, its efficacy diminishes beyond 4 nm. Furthermore, mid-cap annealing allows for precise structure tuning and spectral narrowing, though its effect diminishes as the IC thickness approaches the average QD height. We conclude that mid-cap annealing trims the QD size while the InGaAs IC suppresses intermixing-induced shrinking; used simultaneously, these techniques provide a precise control over PL emission.