Analysis of hole mobility and strain in a Si/Si0.5Ge0.5/Si metal oxide semiconductor field effect transistor

The hole mobility has been measured in a metal-oxide semiconductor field-effect transistor featuring a 6 nm Si 0.5 Ge 0.5 conduction channel. Physical characterization and analysis of the electrical properties confirm that the channel is fully strained. At a total sheet carrier concentration, p s , of 10 12 cm −2 , the 300 K mobility of 220 cm 2 V −1 s −1 is double that of a Si control device (and at 4 K has a peak value of 1800 cm 2 V −1 s −1 ). This improvement is largely maintained up to p s ∼ 10 13 cm −2 , despite the onset of conduction in a parallel Si channel at the oxide interface. Comparing the measurements with calculations suggests that the mobility is affected more strongly by interface roughness than by alloy scattering.