Investigation of interface characteristics in strained-Si nMOSFETs

We investigate and compare the effects of silicon thicknesses on interface characteristics in strained-Si nMOSFET fabricated on SiGe virtual substrate. Ge out-diffusion effect and slight strain relaxation in Si-cap layer are observed with capacitance-voltage measurements. The low-frequency noise characteristics were used to further investigate the interface transport mechanisms and show the same tendency. Moreover, experimental results show that the unified model, i.e. carrier number fluctuation model, including correlated mobility fluctuation is more suitable to interpret the mechanism of 1/f noise in strained-Si devices. Carrier number fluctuation dominates the 1/f noise in weak inversion, but the mobility fluctuation contributes to strong inversion.