Perfect alignment and preferential orientation of nitrogen-vacancy centers during CVD growth of diamond on (111) surfaces

Synthetic diamond production is key to the development of quantum metrology and quantum information applications of diamond. The major quantum sensor and qubit candidate in diamond is the nitrogen-vacancy (NV) color center. This lattice defect comes in four different crystallographic orientations leading to an intrinsic inhomogeneity among NV centers that is undesirable in some applications. Here, we report a microwave plasma-assisted chemical vapor decomposition (MPCVD) diamond growth technique on (111)-oriented substrates that yields perfect alignment ($94\pm2%$) of as-grown NV centers along a single crystallographic direction. In addition, clear evidence is found that the majority ($74\pm4%$) of the aligned NV centers were formed by the nitrogen being first included in the (111) growth surface and then followed by the formation of a neighboring vacancy on top. The achieved homogeneity of the grown NV centers will tremendously benefit quantum information and metrology applications.