Electron transport in the quantum hall regime in strained si/sige

In this paper, modulation-doped Si/SiGe heterostructures are utilized to study electron transport in strained Si in the quantum limit. The integer and fractional quantum Hall effects are observed in samples with mobility in excess of 3 × 105 cm2/(Vs), and show some similarities and some striking differences when compared to the more studied GaAs/AlGaAs heterostructure system. In particular, the disappearance of the v = 5/3 filling factor, the observation of v = 1/2 filling factor in a single quantum well, and the observation of a non-reentrant insulator transition in a specific density range and at high magnetic fields, are all exciting observations which may shed some light on the quantum transport theory in valley-degenerate materials.