Metal-insulator Transition of 2D Electrons in a Modulation Doped Si/Si1−xGex Heterostructure

We report the observation of the apparent metal‐insulator transition (MIT) of two‐dimensional electrons in a high quality modulation doped Si/Si1−xGex heterostructure. The critical density nc, at which the thermal coefficient of its low temperature resistivity changes sign, is 0.32×1011 cm−2, much smaller than the nc of ∼ 0.8×1011cm−2 seen in clean Si‐MOSFET’s. This is consistent with previous observations in 2D holes in GaAs that nc decreases with decreasing disorder.