Photoluminescent Color Centers in Foundry Silicon Photonics
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Authors
Allo, Prosper Dellah
Date
2025-05-27
Type
thesis
Language
eng
Keyword
Silicon defect centers , Silicon defects in foundry , Quantum emitters , Cryogenic silicon photonics , Color centers
Alternative Title
Abstract
Silicon photonics has emerged as a transformative platform for addressing the growing demands of data centers, communication networks, and quantum technologies. By leveraging Complementary Metal-Oxide-Semiconductor (CMOS)-compatible fabrication processes, silicon photonics offers scalability, cost-effectiveness, and high performance. However, the integration of efficient on-chip light sources remains a critical challenge due to silicon’s indirect bandgap, which limits its ability to emit light efficiently. This limitation has hindered the full realization of silicon photonics’ potential, particularly in applications requiring integrated light sources for classical and quantum technologies. This thesis investigates luminescent defect centers, specifically W-centers, as a promising solution for on-chip light generation. W-centers are formed through controlled lattice damage and thermal annealing, creating localized states that enable strong radiative recombination. Unlike hybrid integration of III-V materials or rare-earth doping, W-centers provide a CMOS-compatible pathway to scalable light sources. This work demonstrates the successful formation of W-centers in silicon photonic integrated circuits fabricated using a mainstream foundry process. A novel back-end-of-line (BEOL) ion implantation and annealing process was developed to create W-centers through the standard 3-micrometer oxide encapsulation layer inherent to foundry-fabricated devices and to optimize recipe parameters. The experimental results presented in this thesis confirm efficient photoluminescence (PL) from W-centers with brightness comparable to unencapsulated reference samples. The study also explores the optimization of implantation energies, fluences, and Circular Bragg Gratings to enhance light extraction and collection efficiency. The findings demonstrate that W-center PL originates from the silicon-on-insulator (SOI) device layer, validating the compatibility of the BEOL process with mainstream foundry platforms. This work represents a significant advancement in the integration of defect-based light sources into mainstream foundry-fabricated silicon photonic devices. It paves the way for scalable and cost-effective integration of classical and quantum light sources by circumventing the challenges associated with silicon's indirect bandgap. The demonstrated approach is versatile and potentially adaptable to other defect centers, offering a pathway for further advancements in silicon photonics. The implications of this work extend to applications such as quantum computing and photonic artificial intelligence, unlocking new opportunities for energy-efficient and scalable silicon photonic technologies.
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Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution 4.0 International