Deterministic Positioning of Circular Bragg Gratings Using Atomic Force Lithography for Quantum Dot Light Sources

Abstract The scalable realization of high-performance quantum networks requires the deterministic integration of quantum emitters into photonic microcavities with nanometer-scale precision. While semiconductor quantum dots (QDs) are near ideal quantum light sources, their random spatial distribution remains a significant bottleneck for device reproducibility. We report a room-temperature, atomic force microscopy-assisted nano-oxidation lithography technique that enables the deterministic positioning of buried GaAs QDs with a practical accuracy of 51(28) nm. By integrating these positioned emitters into monolithic, free-standing circular Bragg gratings with a vertically asymmetric membrane structure, we achieve a 245-fold photoluminescence intensity gain while maintaining a low fine-structure splitting comparable to bulk QDs. Through a combination of polarization-resolved spectroscopy and finite-difference time-domain simulations, we demonstrate that this positioning precision ensures robust, symmetric emission with a polarization imbalance below 5% (Stokes parameter |S| < 0.05). This monolithic approach bypasses complex membrane transfer processes and cryogenic mapping, offering a high-throughput and industrially accessible route to high-fidelity entangled-photon sources for large-scale quantum information technologies.