Epitaxial growth of two-dimensional electron gas (2DEG) in strained silicon for research on ultra-low energy electronic processes

Abstract

We present a review of the progress in the field of 2DEG in strained Si/SiGe heterostructures during the past 20 or so years. We highlight the difference in the key challenges in sample preparation between the samples for low-temperature transport studies and those for field-effect transistor (FET) applications. The requirements of low electron density and high electron mobility for low-temperature electron transport are also discussed. High mobility (> 300,000 cm 2/V s) can be reproducibly achieved recently and low electron sheet density (1.1 × 10 11 cm − 2 ) in modulation-doped samples (as opposed to gated) has also been observed. Magnetotransport measurements provide indications of the mobility limiting factors thereby pointing to the plausible directions for further improvements on the strained Si sample quality.