Development of Thin SiGe Relaxed Layers with High-Ge Composition by Ion Implantation Method and Application to Strained Ge Channels

Very thin SiGe relaxed buffer layers whose Ge composition was higher than 40% were fabricated by utilizing ion implantation method. Strain relaxation ratio of 70% with respect to Si was obtained. Rms roughness of the sample with Si⁺ implantation was only 0.45 nm in spite of high Ge composition and was much smaller than that of the sample without ion implantation. It was confirmed by cross-sectional transmission electron microscope (XTEM) observation that few threading dislocations existed in the Si_0.53Ge_0.47 layer. P-type modulation doped strained Ge channel structure formed on the Si_0.53Ge_0.47 buffer showed hole Hall mobilities as high as 16500 and 1450 cm²/(V s) at low and room temperatures, respectively. These results indicate that ion implantation method is promising for realization of high-performance strained channel heterostructure devices based on high Ge composition SiGe substrates.