Carrier recombination mechanisms at quantum point defects in wide band gap two-dimensional materials*

The identification and design of defects in two-dimensional (2D) materials as promising defect based qubits and single photon emitters requires a deep understanding of the underlying carrier recombination mechanisms. Yet, the dominant mechanism of carrier recombination at defects in 2D materials has not been well understood. In order to address these concerns, we developed first-principles methods to calculate the radiative and nonradiative recombination rates at defects in 2D materials, using h-BN as a prototypical example. We reveal the carrier recombination mechanism at defects in 2D materials being mostly dominated by defect-defect state recombination. In particular, we disentangle the nonradiative recombination mechanism into key physical quantities: the zero-phonon line and Huang-Rhys factor. At the end, we identified that strain can effectively tune the electron-phonon coupling at defect centers and drastically change the nonradiative recombination rates. This work serves as a general platform for understanding carrier recombination at defects in 2D materials, while providing pathways for engineering of quantum efficiency.
[1] Feng Wu, Tyler J. Smart, Junqing Xu, and Yuan Ping, Phys. Rev. B 100, 081407(R) (2019).