Photonic Properties of InAs Quantum Dots by Post-Growth Maskless Site-Selective Focused Ion Beam Implantation

We report the maskless site-selective modification of InAs quantum dot (QD) photonic properties via focused ion beam (FIB) implantation of antimony (Sb, group V), controlling emission wavelength and linewidth. Contrasting postgrowth methods yielding emission blueshift, our approach achieves bidirectional (blue and red) emission wavelength shifts, offering flexibility, without requiring an implantation mask for site selectivity. Our experimental results also address inhomogeneous broadening due to size and spatial variations in epitaxial QDs enhancing spectral uniformity. Additionally, focused ion implantation suppresses wetting layer (WL) emission, improving spectral purity, with controlled PL reduction tailored by ion dose. The wider ability to achieve red shifts enhanced linewidth and reduced WL emission without using postimplantation thermal annealing through this method is confirmed using boron (B, group III). Selected for its contrasting electronic doping and significantly different mass compared with Sb, consistent spectral modification was achieved. Dynamic and static simulations were carried out to determine ion and defect profiles, and intermixing corroborated by high-resolution micro-PL spectroscopy resolving individual QD emission. This scalable approach supports site-selective QD engineering for advanced photonic integrated circuits (PICs), nanophotonic, and quantum systems such as single-photon emitters and solid-state quantum memories.