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 (εc) and hole mobility (μh) 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 εc introduced during Ge condensation was strongly dependent on d and Ge%. Thinner d is helpful for maintaining higher εc when Ge% is 50%. εc is dramatically relaxed with a further increase in Ge%. By varying the tradeoff between Ge% and εc, we achieved a maximum μh of approximately 570 cm2/V·s in the d range of 9–11 nm and Ge% range of 50–65%.