Fabrication of thin strain-relaxed SiGe buffer layers with high Ge composition by ion implantation method

Highly strain-relaxed 80-nm-thick SiGe layers with Ge composition of 47% were successfully grown on Si substrates by the ion implantation method. Strain relaxation ratios were 76% and 82% for Si+ and Ar+ implantation, respectively, and rms roughness of the samples with ion implantation was found to be less than 1 nm in spite of the high Ge composition. Uniform crosshatch patterns with rms roughness of 0.45 nm were observed for the sample with Si+ implantation, while random roughness patterns appeared in the case of Ar+ implantation. XTEM observation indicated that a quite few threading dislocations were induced in the Si0.53Ge0.47 layer. Fully strained Ge channels with smooth surface could be fabricated on this Si0.53Ge0.47 layer, and hole Hall mobilities as high as 16,500 and 1450 cm2/V s at low and room temperatures, respectively, were obtained.