The dependence of the $g$ factors of semiconductor donors on applied electric and magnetic fields is of immense importance in spin-based quantum computation and in semiconductor spintronics. The donor $g$-factor Stark shift is sensitive to the orientation of the electric and magnetic fields and is strongly influenced by the band-structure and spin-orbit interactions of the host. Using a multimillion atom tight-binding framework, the spin-orbit Stark parameters are computed for donors in multivalley semiconductors, silicon, and germanium. Comparison with limited experimental data shows good agreement for a donor in silicon. Results for gate-induced transition from three-dimensional to two-dimensional wave-function confinement show that the corresponding $g$-factor shift in Si is experimentally observable, and at modest $B$ field, O(1 T) can exceed the Stark shift of the hyperfine interaction.

• Received 17 August 2009

DOI:https://doi.org/10.1103/PhysRevB.80.155301