Influence of SiGe layer thickness and Ge fraction on compressive strain and hole mobility in a SiGe-on-insulator substrate fabricated by the Ge condensation technique

Both compressive strain (ε _c) and hole mobility (μ _h) were investigated for SiGe-on-insulator substrates with different values for the SiGe layer thickness (d) and Ge fraction (Ge%), which were fabricated by Ge condensation. We found that the ε _c introduced during Ge condensation was strongly dependent on d and Ge%. Thinner d is helpful for maintaining higher ε _c when Ge% is 50%. ε _c is dramatically relaxed with a further increase in Ge%. By varying the tradeoff between Ge% and ε _c, we achieved a maximum μ _h of approximately 570 cm ²/V•s in the d range of 9-11 nm and Ge% range of 50-65%.