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

Modulation doped n-type Si/Si0.7Ge0.3 quantum wells exhibited the integer q uantum Hall effect at integer filling factor nu = 2, 3, 4, 5, 6, 8, 10,... Odd-integer filling factors showed the two-fold valley splitting, while eve n-integer filling factors indicated inter- and spin splitting. From an anal ysis of the thermally activated resistivity as a function of the magnetic f ield 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 t he quantum relaxation time (similar to 9) indicated that the dominant scatt ering mechanism was long-range remote ion scattering. (C) 2000 Elsevier Sci ence Ltd. All rights reserved.