Low temperature magnetotransport phenomena in modulation-doped Si/Si1−xGex quantum well structures grown by gas-source MBE

Modulation doped n-type Si/Si0.7Ge0.3 quantum wells exhibited the integer quantum Hall effect at integer filling factor ν=2,3,4,5,6,8,10,… Odd-integer filling factors showed the two-fold valley splitting, while even-integer filling factors indicated inter- and spin splitting. From an analysis of the thermally activated resistivity as a function of the magnetic field in the quantum Hall regime we deduced the energy gaps of Landau level and pre-exponential factor. The ratio of the transport relaxation time to the quantum relaxation time (∼9) indicated that the dominant scattering mechanism was long-range remote ion scattering.