Effects of interface charge on the quantum Hall effect

The dependence of the quantum Hall effect on systematic changes in the electronic scattering has been studied in experiments on the inversion layer electrons in Si metal-oxide-semiconductor field-effect transistors which have driftable ${\mathrm{Na}}^{+}$ ions in the oxide. The widths and positions of the quantum Hall plateaus corresponding to filled valley levels, filled spin levels, and filled Landau levels were measured for oxide charges up to ${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}2}$ at a temperature of 1.35 K and a magnetic field of 13 T. The widths of the plateaus were observed to increase with increasing oxide charge, which is consistent with a picture in which the number of localized states at band edges increases with increased electronic scattering. With increasing interface charge, however, the positions of the plateaus corresponding to filled valley and filled spin levels exhibited systematic shifts with respect to those for filled Landau levels.