Huebl, H.H.HueblStegner, A.R.A.R.StegnerStutzmann, M.M.StutzmannBrandt, M.S.M.S.BrandtVogg, G.G.VoggBensch, F.F.BenschRauls, E.E.RaulsGerstmann, U.U.Gerstmann2022-03-032022-03-032006https://publica.fraunhofer.de/handle/publica/21174210.1103/PhysRevLett.97.1664022-s2.0-33750216376The hyperfine interaction of phosphorus donors in fully strained Si thin films grown on virtual Si1-xGex substrates with x <= 0.3 is determined via electrically detected magnetic resonance. For highly strained epilayers, hyperfine interactions as low as 0.8 mT are observed, significantly below the limit predicted by valley repopulation. Within a Green's function approach, density functional theory shows that the additional reduction is caused by the volume increase of the unit cell and a relaxation of the Si ligands of the donor.en621530journal article