Preferential Placement of Aligned Nitrogen Vacancy Centers in Chemical Vapor Deposition Overgrown Diamond Microstructures

Abstract

The usefulness of nitrogen vacancy (NV) centers in diamond is augmented by a low defect and impurity density in the surrounding host material, and applications benefit from the ability to control the position of the NV centers. Herein, a process to create NV centers on single‐crystalline diamond microstructures by chemical vapor deposition (CVD) is presented. Pyramidal structures with {111} side facets are formed during the intrinsic overgrowth of dry chemically etched cylindrical pillars on a substrate with {100} surface orientation. A thin nitrogen‐doped epitaxial layer is deposited on top of the pyramids resulting in the creation of NV centers exclusively on the {111} pyramid side faces. Optically detected magnetic resonance (ODMR) and spin echo measurements reveal preferential alignment of the NV centers in a single {111} direction and a T 2 time of 55 μs . The T 2 time of the NV centers is limited by the surrounding substitutional nitrogen (P1 center) concentration of [P 1 ] = 5 ppm . A low density of other paramagnetic spin noise is detected by double‐electron electron resonance (DEER) measurements.

Epitaxial Lateral Overgrowth of Wafer‐Scale Heteroepitaxial Diamond for Quantum Applications

“…In contrast, the areas corresponding to a low‐doped core and a conventional (100) epilayer generate a much lower signal. Comparing these results with the previous studies carried out on homoepitaxial films, [ 6 ] we might assume that during crystallization in <111> direction in a so‐called “step‐flow‐growth” mode, a nearly uniform alignment of NVs is achieved on each {111} facet, where each NV orientation corresponds to one of four possible orientations of the NV pair in the diamond sp 3 lattice. [ 17 ]…”

“…Further details on RIE and related pattering procedures can be found elsewhere. [6] Further processing of type I HD wafers using mechanical planarization/polishing processes, followed by the removal of the silicon substrates and by Ir sputter epitaxy, allows for the fabrication of very high-quality Ir layers. Ir_on_HD samples have a low initial stress and ensure a high-density BEN/CVD of HD microcrystals with a dramatically improved orientation grade of isolated microcrystals (type III, see Figure 1d).…”

“…More detailed information on ODMR and T 2 * measurements can be found elsewhere. [6,10] 3. Results and Discussion…”

“…In particular, N(P1) and NV densities, along with a dephasing time T 2 *, have been experimentally obtained and compared to those measured on homoepitaxial reference samples. [ 6 ] In addition, potential advantages of secondary BEN/CVD processing on Ir‐on‐diamond substrates (type III) are briefly discussed and the crystal quality of epilayers of different types is compared. In addition to quantum performance parameters, the results on microstructural and optical characterization of HD epilayers are reported highlighting the advances of ELO in achieving a “quantum grade” for diamond thin films on a wafer scale.…”

A Chemical Vapor Deposition Diamond Reactor for Controlled Thin‐Film Growth with Sharp Layer Interfaces

“…[ 6 ] We recently achieved accurate positioning of NV centers on diamond microstructures oriented along their specific {111} growth directions. [ 7 ] With such an approach, the placement of individual NVs and specific orientation may become possible in future. Accurate positioning of NV centers is of high importance for applications in quantum sensing like scanning probe magnetometry with diamond probes.…”