Structural and electronic properties of NV ⁰ and NV ⁻ centers in diamond under uniaxial strain: a first-principles study

Strain engineering, a pivotal method for tuning material properties, shows great promise in extending the application scope of wide-band-gap semiconductors such as diamond. Nitrogen-vacancy (NV) centers, an important defect system in diamond, are generally present in either a neutral (NV0) or a negative charge state (NV−). The spin-triplet nature of the NV− state makes it a powerful platform for quantum sensing. However, the reliability of NV-center-based quantum sensing is subjected to the charge state transition between NV0 and NV− states, and it is of fundamental importance to provide precise control of the charge state of NV centers and to enhance the stability of the NV− state. Here, we systematically investigated the influence of uniaxial strain applied in the [100], [110], and [111] crystallographic directions on the electronic structure and charge state stability of NV color centers through first-principles calculations. We found that uniaxial strain can exert a significant impact on the stability of the NV0 and NV− centers, and the impact is highly dependent on the crystallographic orientation. In particular, the application of tensile strain along the [100] and [110] directions can result in a remarkable enhancement of the stability of the desired NV− state. Based on thorough analyses of the band structure and density of states (DOS), we elucidated the underlying electronic mechanism by which strain modulates the properties of NV centers.