UC Davis

Defects in wide bandgap semiconductors, known as color centers, are prominent candidates for solid-state quantum technologies due to their attractive properties, including near identical single photon emissions, optical interfacing, long coherence times, and scalability potential. Among the available host materials, silicon carbide (SiC) is desirable for its quantum-grade wafer availability and advanced processing capabilities. To realize the full potential of the color centers in SiC, the efficiencies of emission, collection and detection of the single photons need to significantly enhance compared to those values in bulk. This enhancement can be achieved through photonic integration of color centers, which increases the light-matter interaction. Challenges in maintaining the pristine quality of color centers have led to photonic integration moving away from the established nanofabrication processes and toward alternative approaches that require non-standard sample preparation and lack scalability. Bulk processing techniques such as the Faraday cage-assisted angle etching and ion beam etching produce suspended photonic structures with triangular cross-section. Ion beam etching has been used to illustrate a wafer-scale process in diamond, leading to significant advancements in quantum information processing experiments. However, a similar wafer-scale etching process is currently unavailable in SiC, and there is limited understanding of the behavior of light in these novel triangular photonics.

This dissertation presents the development of novel, wafer-scale, triangular cross-section photonics for color centers in SiC suitable for quantum information processing applications, studied through modeling, nanofabrication, and 4f confocal spectroscopy. This includes modeling efficient photonic devices such as waveguides, photonic crystal mirrors and nanopillars for improving collection efficiencies, photonic crystal cavities for enhancing the single photon emission, photonic molecule appropriate for studying cavity quantum electrodynamics systems, and superconducting nanowire single photon detectors integrated with waveguides for efficient detection of color center emission. Next, we develop a nanofabrication process to generate and integrate nitrogen vacancy centers in 4H-SiC into nanopillars for the first time and confirmed the enhancement in collection efficiency through 4f confocal spectroscopy. As a crowning achievement of this effort, we develop a novel wafer-scale ion beam etching process to fabricate triangular cross-section photonics in 4H-SiC, that does not interfere with the integrated color center emission properties.