Bottom-Up Synthesis of Single Crystal Diamond Pyramids Containing Germanium Vacancy Centers

Diamond resonators containing color-centers are highly sought after for application in quantum technologies. Bottom-up approaches are promising for the generation of single-crystal diamond structures with purposely introduced color centers. Here the possibility of using a polycrystalline diamond to grow single-crystal diamond structures by employing a pattern growth method is demonstrated. For, the possible mechanism of growing a single-crystal structure with predefined shape and size from a polycrystalline substrate by controlling the growth condition is clarified. Then, by introducing germanium impurities during the growth, localized and enhanced emission from fabricated pyramid shaped single-crystal diamonds containing germanium vacancy (GeV) color centers is demonstrated. Finally, linewidth of ∼500 MHz at 4 K from a single GeV center in the pyramid shaped diamonds is measured. The method is an important step toward fabrication of 3D structures for integrated diamond photonics.