Crystallographic Orientation Dependent Dry Etch in Single Crystal Diamond

Sculpturing desired shapes in single crystal material is ever more crucial in the realization of complex devices for nanophotonics, quantum computing, and quantum optics. The crystallographic orientation dependent wet etch of single crystalline silicon in potassium hydroxide (KOH) allows a range of shapes formed and has significant impacts on MEMS (microelectromechanical systems), AFM (atomic force microscopy), and microfluidics. Here, a crystal direction dependent dry etching principle is presented, which allows to selectively reveal desired crystal planes in monocrystalline diamond. The etch process does not involve mechanical tilting of sample stages or metallic cages. Using the principle, monolithic diamond nanopillars for magnetometry using nitrogen vacancy centers are fabricated. In these nanopillars, a record half-tapering angle is achieved for a high photon efficiency and high mechanical strength of the nanopillar. These results represent the first demonstration of crystallographic orientation dry etch principle, which opens a new window for shaping specific nanostructures which is at the heart of nanotechnology. It is believed that this principle will prove to be valuable for structuring and patterning of other single crystal materials as well.