HIGH ELECTRON MOBILITIES IN SURFACTANT-GROWN GERMANIUM ON SILICON SUBSTRATES

We present the first investigation of the electrical properties of rel axed Ge layers grown on Si(111) substrates by surfactant-mediated epit axy with Sb. Electron Hall mobilities and carrier concentrations of 1 mu m thick epitaxial Ge layers grown on p-type Si-substrates at temper atures between 640 degrees C and 720 degrees C were determined at 300 It and 77 K. The highest electron mobilities, 3100 cm(2)/Vs and 12300 cm(2)/Vs, at 300 K and 77 K, were observed in the 720 degrees C sample . At 300 K an electron concentration of only 1.1x10(16) cm(-3) was mea sured suggesting a substantially lower incorporation of the surfactant Sb compared to earlier publications. The low Sb doping was independen tly supported by secondary ion mass spectroscopy (SIMS).