Effect of diamond growth mode on nitrogen-vacancy distribution

The nitrogen-vacancy (NV) center in diamond, known for its long electron spin coherence and room-temperature optical addressability, is a promising platform for solid-state quantum sensing. Microwave plasma chemical vapor deposition (MPCVD) is widely used to fabricate NV center ensembles; however, the commonly assumed spatial uniformity of these ensembles remains insufficiently verified. Since the spatial distribution of NV centers influences the accuracy of magnetic imaging, understanding its origin is essential. In this work, the distribution of ensemble NV centers in an MPCVD-grown diamond is not random but is dictated by the underlying growth mode: when the gas composition, chamber pressure, and microwave power are held constant, a reduced growth temperature favors the step-bunching growth mode on the substrate surface. This enhances the vacancy mobility, thereby enriching the NV centers and resulting in a higher fluorescence intensity. With increasing temperature, the growth mode shifts from step-bunching to island growth, which impedes vacancy migration, thereby lowering the concentration of NV centers. This study provides insight into the relationship between growth conditions, surface morphology, and NV center distribution, and offers a basis for the controlled fabrication of high-density and spatially uniform NV ensembles. Such control is expected to support improved sensitivity in wide-field magnetic imaging and related applications.