Fabrication and Investigation of Diamond Membranes for Photonic Nanostructures

Due to its exceptional physical and chemical characteristics, diamond in a form of thin membranes is a particularly promising material for the fabrication of high-quality photonic devices. Especially for envisioned applications in quantum information technologies and communication, diamond gained, as a host material, an ever-increasing scientific interest based on remarkable properties of different color centers in its crystal lattice, e.g. nitrogen-vacancy centers, serving as single-photon emitters. As a high index material only a small fraction of the emitted photons by the color centers can be collected outside diamond. Therefore, to enhance the photon collection efficiency the color centers needs to be coupled to light confining architectures like open micro cavities or photonic diamond nanostructures. The focus of this work was the fabrication and optimization of thin diamond membranes. Thereby, one main goal was to reduce by different planarization procedures the overall surface roughness and defects acting as scattering centers. The diamond membranes were used either for an integration into open fiber-based Fabry-Pérot microcavities to enhance the color centers’ emission or for further fabrication of photonic nanostructures. In this context processes for structuring of membranes and photonic nanostructures were developed and improved by different parameters during the cleaning processes, electron beam lithography and reactive ion etching. Their impact on the generated structures have been investigated.