The direct bonding process of a diamond-on-insulator (DOI) substrate enables monolithic integration of diamond photonic structures for quantum computing by improving photon collection efficiency and entanglement generation rate between emitters. It also addresses key fabrication challenges, such as robustness, bonding strength, and scalability. This study investigates strain effects in DOI substrates following direct bonding. Strain generation is expected near the diamond–SiO₂/Si interface due to the thermal expansion coefficient mismatch between the bonded materials. Strain-induced lattice distortions are characterized using nitrogen-vacancy (NV) centers in diamond via optically detected magnetic resonance (ODMR) and photoluminescence (PL) mapping. PL mapping reveals interference fringes in unbonded regions, indicating bonding irregularities. Depth-resolved ODMR measurements show a volumetric strain component increase of ≈0.45 MHz and a shear component increase of ≈0.71 MHz between the top surface and the DOI interface. However, ODMR signal contrast and peak linewidth remain largely unaffected, suggesting no visible deterioration in the optical properties of the emitters. By combining ODMR and PL mapping, this work establishes a robust methodology for assessing bonding quality and strain impact on NV centers, an essential step toward advancing scalable quantum technologies and integrated photonic circuits. ... Read more

This dissertation presents advancements toward the development of a compact quantum biosensor by integrating nitrogen-vacancy (NV) centers in diamond with CMOS-fabricated Single-Photon Avalanche Diode (SPAD) arrays. It combines efforts across various research domains and includes simulations, design, and experimental work, in order to tackle challenges in quantumsensing, imaging, fabrication, and device integration.
A custom confocal Optically Detected Magnetic Resonance (ODMR) setup was designed and employed to study magnetic properties in biosamples. HEK293T cells cultured on diamond substrates were tagged with superparamagnetic nanoparticles to act as magnetic probes. Measurements included photoluminescence (PL) mapping and 2D ODMR scans. Although the weak magnetization of the nanoparticles limited magnetic field detection, it still proved the feasibility of such a bio-imaging method and highlighted areas for improvement.... ... Read more