2-DIMENSIONAL ELECTRON-GAS PROPERTIES OF SYMMETRICALLY STRAINED SI/SI1-XGEX QUANTUM WELL STRUCTURES

n-type modulation-doped Si/Si0.5Ge0.5 strained layer multiple quantum well structures have been grown on (100)Si substrates by molecular beam epitaxy. The concept of strain symmetrization has been applied by inserting a strain-relaxed SiGe buffer layer. The samples have been investigated by Hall measurements supplemented by Shubnikov-de Haas and Rutherfored backscattering analysis. We present mobility results on the two-dimensional electron gas in the silicon wells as a function of electron concentration, quantum well width, and spacer thickness. The influence of the sample parameters on the electron mobility is discussed. With an electron sheet concentration of 2.4×1012 cm-2 per well, a well width of 10 nm, and a spacer thickness of 10 nm a Hall mobility at room temperature of 1280 cm2 (V s)-1 has been achieved. © 1990.