Density functional theory of strain engineering on single photon emitter in hexagonal boron nitride

Hexagonal boron nitride has been found as excellent host for color centers as single photon emitters. The complex defect which is a nitrogen vacancy next to a nitrogen antisite (V_NN_B) is regarded as promising candidate due to the nontrivial electronic structure.^1,2 Here, using density functional theory, we provide detailed investigation of the geometric and electronic evolution of V_NN_B under external strain. The V_NN_B prefers the C_1h symmetry making the defect as a dynamic Jahn-Teller system.³ By lowing the symmetry, the first transition which considered to be a dark state can be activated, inducing the compete between two possible excitation pathways.⁴ The zero phonon line shows non-linear evolution as a function of in plane strain indicating the important role of the out of plane strain between defect atom and its ambient structure. It is predicted that a significantly stronger redshift than blueshift of emission can be realized by applying armchair strain. Our analysis provides insightful understanding of the color centers as single photon emitters.

(1) Tran, T. T.; et al. Nature Nanotech 2016, 11 (1), 37–41.
(2) Abdi, M.; et al. ACS Photonics 2018, 5 (5), 1967–1976.
(3) Noh, G.; et al. Nano Lett. 2018, 18 (8), 4710–4715.
(4) Wu, F.; et al. Phys. Rev. B 2019, 100, 081407(R).