Fabrication and characterization of diamond nanopillars, waveguides and AFM tips with incorporated color centers

Diamond is a unique material with outstanding properties and the perfect host for different crystal defects in its lattice, so-called color centers, which provide exceptional spin properties, rendering them a promising platform for the development of novel devices and components in quantum information technologies (QIT) and quantum sensing applications. To overcome diamond's high internal reflection due to its high refractive index, color centers need to be incorporated in photonic diamond structures, leading to enhanced photon collection efficiencies and therefore better performances of the final devices. In addition, the incorporation of NV centers in diamond AFM tips allows for the realization of scanning probes as magnetic sensors in nanoscale magnetometry. The focus of this thesis was on the fabrication and optimization of different photonic diamond nanostructures, such as suspended waveguides and nanopillars for the integration of NV and SiV centers, as well as AFM tips for the incorporation of NV centers within their apices. In this regard, different fabrication parameters during electron beam lithography and reactive ion etching and their impact on the final quality of the nanostructures have been investigated. SiV centers have been generated in situ during diamond growth in nanopillars, while NV centers were created at nanotips by vacancy-induced He ion implantation into nitrogen-rich type Ib diamond and subsequent annealing. The thesis starts with a short introduction, highlighting the importance of the current research. The second chapter covers the theoretical background, which provides an adequate understanding of the fundamental diamond properties, diamond growth, color centers and the application of diamond nanostructures. The experimental procedures, systems and materials are introduced in chapter 3. The following chapter 4 presents the main results in regard to the development of fabrication processes for diamond waveguides, nanopillar arrays and AFM tips. The presence of incorporated color centers within the fabricated diamond nanostructures are discussed on the basis of optical measurements (fluorescence mapping and photoluminescence) in chapter 5. Finally, the thesis concludes with a summary and an outlook, including possibilities for future work.