Low-temperature investigation of the magnetoresistivity in modulation-doped Si/SiGe quantum wells

We have performed magnetotransport measurements up to 15 T at temperatures down to 30 mK on a set of n-channel Si/SiGe modulation-doped samples grown by using gas source molecular beam epitaxy. The presences of clear quantum Hall plateaus and dissipationless resistivity minima attest to the high qua lity of this material. Analysis of the occurrence of integer, spin-split an d valley-split mininia in the Shubnikov-de Haas oscillations has been perfo rmed using Ando's model for Landau level broadening by a Gaussian scatterin g potential.