Strained Donor-Bound Excitons in ²⁸Si

We present a comprehensive experimental study of the neutral donor to donor-bound exciton transition D$⁰$$→ $D$⁰$X in isotopically enriched ²⁸Si, focusing on the group-V donors P, As, and Sb under finely tuned uniaxial stress along the [100] and [110] crystal axes and magnetic fields from 3.5 mT to 1.7 T. From these measurements, donor-specific deformation potentials are extracted. The uniaxial electron deformation potential Ξ_u is found to be significantly larger than values reported for other states or transitions in silicon and shows a clear dependence on the donor species, indicating an increased sensitivity of the D⁰X state to strain and central-cell effects. We also observe a magnetic field dependence of the hole shear deformation potential d, suggesting a more complex strain coupling mechanism than captured by standard theory. Diamagnetic shift parameters determined from Zeeman spectra show good agreement with earlier measurements. Our results provide a refined parameter set critical for the design of silicon quantum devices based on D⁰X transitions.