Weak localization in the 2D metallic regime of Si-MOS

The negative magnetoresistance due to weak localization is investigated in the two-dimensional metallic state of Si-MOS structures for high conductanc e values between 35 and 120 e(2)/h. The extracted phase coherence time is e qual to the momentum relaxation time at 10 K but nearly 100 times longer at the lowest temperature. Nevertheless, only weak logarithmic corrections to the conductivity are present in the investigated temperature and concentra tion range thus proving the absence of strong quantum effects due to electr on-electron interaction. From saturation effects of the phase coherence tim e a lower boundary for spin-orbit scattering of about 200 ps is estimated.