First‐Principles Investigation of the T‐ and M‐Centers in Silicon Using Meta‐GGA Functionals

Abstract Quantum defects in silicon (Si), particularly the T‐center, have emerged as a promising spin‐photon interface and single‐photon emitter for quantum communication applications, due to their telecom‐compatible emission and favorable spin coherent properties. Recent advances have enabled the detailed characterization of these centers in Si, and the discovery of quantum defects in Si is especially important due to their high processability and compatibility with current technologies. Here, a systematic study of the T‐center and, more importantly, an unexplored related defect, the M‐center, is presented using density functional theory (DFT) with the meta‐GGA functional r 2 SCAN. For the already studied T‐center, the findings against the established hybrid functional HSE06 results are extensively discussed. The calculations on the T‐center demonstrate excellent agreement with the HSE06, reinforcing the efficiency of meta‐GGA approaches for accurate defect characterization in Si. Moreover, the M‐center is introduced and characterized, revealing promising quantum optical properties. Both centers are found to arise from a bound exciton configuration, and for this process the zero‐phonon line (ZPL) and the zero‐field splitting (ZFS) are calculated.