[TuP3A] Epitaxy and process

[TuP3A-03] Independent Control of InAs Quantum Dot Geometry and Composition via InGaAs Bilayer Capping and Mid-Cap Annealing

〇Rhenish Simon¹, Haruto Okuizumi¹, Kazuki Koyama¹, Ronel Christian Roca¹, Itaru Kamiya¹ (1. Toyota Technological Institute (Japan))

InAs quantum dot (QD) energy levels are primarily determined by size, composition, and the surrounding matrix. While GaAs capping protects QDs, it induces "natural shrinkage" via strain-driven In-Ga intermixing. In this work, we investigate and control this process by combining an InGaAs initial cap (IC) with a mid-cap annealing step, also known as "In-flush." By comparing photoluminescence (PL) measurements with numerical energy band simulations, we decouple the structural and chemical evolution of the QDs. Our results reveal that while capping-induced shrinkage in samples without mid-cap anneal (“No-Flush”) is driven by surface mass movement at a constant composition, the In-flush technique enables independent tuning of Indium concentration through thermally enhanced segregation. These findings demonstrate that this hybrid technique allows for the precise, independent engineering of both QD geometry and composition.