VERY HIGH 2-DIMENSIONAL HOLE GAS MOBILITIES IN STRAINED SILICON-GERMANIUM

We report on the growth by solid source MBE and characterization of re mote doped Si/SiGe/Si two-dimensional hole gas structures. It has been found that by reducing the Ge composition to less-than-or-equal-to 13 % and limiting the thickness of the alloy layer, growth temperatures c an be increased up to 950-degrees-C for these structures while maintai ning good structural integrity and planar interfaces. Record mobilitie s of 19 820 cm2 V-1 s-1 at 7 K were obtained in normal structures. Our calculations suggest that alloy scattering is not important in these structures and that interface roughness and interface charge scatterin g limit the low temperature mobilities.