Plasma treatments and photonic nanostructures for shallow nitrogen vacancy centers in diamond

Abstract

We investigate the influence of plasma treatments, especially a 0 V-bias, potentially low damage O 2 plasma as well as a biased Ar/SF 6 /O 2 plasma on shallow, negative nitrogen vacancy (NV − ) centers. We ignite and sustain using our 0 V-bias plasma using purely inductive coupling. To this end, we pre-treat surfaces of high purity chemical vapor deposited single-crystal diamond (SCD). Subsequently, we create ∼10 nm deep NV − centers via implantation and annealing. Onto the annealed SCD surface, we fabricate nanopillar structures that efficiently waveguide the photoluminescence (PL) of shallow NV − . Characterizing single NV − inside these nanopillars, we find that the Ar/SF 6 /O 2 plasma treatment quenches NV − PL even considering that the annealing and cleaning steps following ion implantation remove any surface termination. In contrast, for our 0 V-bias as well as biased O 2 plasma, we observe stable NV − PL and low background fluorescence from the photonic nanostructures.

Recent Advances in Single Crystal Diamond Device Fabrication for Photonics, Sensing and Nanomechanics

“…These issues are inherent to top-down fabrication methods and need to be addressed by usage of alternative plasma mixtures, surface treatment methods, etc. [ 4 ]. Other methods to overcome this include combination of both bottom-up and top-down methods to realize diamond nano-structures with enhanced surface and optical properties [ 53 ].…”

“…Optically active point defects called color centers in diamond have proven useful for a wide range of applications which span from sensing magnetic fields e.g., in nano magnetic resonance, single molecule detection and single photon emission to optomechanics, etc. [ 3 , 4 , 5 ]. The most explored point defect in diamond, the nitrogen vacancy (NV) center provides an optically readable electron spin at room temperature even for individual color centers.…”

“…However, the density of color centers and shape/configuration of nano-structures is difficult to control via these methods. On the other hand, top-down approaches allow to create nano-structures with well-defined characteristics (shape, defect density) with high precision, but, require advanced nanofabrication and plasma etching which enhances processing costs [ 4 , 12 ].…”

Reliable Nanofabrication of Single-Crystal Diamond Photonic Nanostructures for Nanoscale Sensing

“…We used a combination of SF6,O2, Ar biased plasmas with mixed RF and ICP discharges. Following recent approaches [22,23], we terminated the etching using low-damage, 0 V bias plasma with pure oxygen. The use of such soft etching was motivated by the potential close-to-surface damage due to highly biased ICP etching [24].…”

“…To investigate the photonic properties of our SCD nanostructures, we used a custom-built confocal microscope (numerical aperture 0.8). Details of the setup are given in References [22,29,30,31].…”