Optimum Design of Channel Material and Surface Orientation for Extremely-Thin-Body nMOSFETs under New Modeling of Surface Roughness Scattering

Mobility reduction due to surface roughness scattering is a critical concern for Extremely-Thin-Body (ETB) nanosheet channels. However, the conventional scattering model cannot explain the experimental results with realistic roughness. In this study, we have proposed a new model of surface roughness scattering, which can explain the experimental mobility of SOI, GOI and InAs-OI nMOSFETs with roughness parameters obtained experimentally from TEM images. Based on this model, we deliver the assessment on the optimum ETB channels down to 2 nm. As a result, the anisotropic valley with heavy confinement mass is expected to have the high immunity to mobility reduction by surface roughness. In particular, (111) GOI is most expected thanks to the strong anisotropy of the L valley and have the excellent surface-roughness-limited electron mobility even in the 2-nm-thick channels, which is an advantage over 2D materials.