Spin relaxation and g-factor of two-dimensional electrons in Si/SiGe quantum wells

We investigate spin relaxation and the g-factor of conduction electrons in modulation doped Si/SiGe quantum wells by means of electron spin resonance. We find that both the transverse- and the longitudinal relaxation times are of the order of microseconds, much longer than in III–V compounds. For high mobility, at carrier densities sufficiently far away from the metal-to-insulator transition, both quantities can be explained consistently in terms of the Bychkov–Rashba field, together with the g-factor anisotropy and its dependence on the carrier density. A single value of the BR coefficient, View the MathML source, explains all data. This value is by more than three orders of magnitude smaller than for III–V compounds owing to the small spin–orbit coupling of Si. The properties found make Si/SiGe quantum structures interesting candidates for quantum computing.