Phonon scattering in Si-based nanodevices

摘要

We employ a recently introduced confined phonon model to investigate electron-phonon interaction and electron mobility in different silicon-on-insulator devices. The dependence on silicon and silicon dioxide layer thickness and on the boundary conditions imposed is analyzed for both single and double gate devices, and the results are compared with those obtained with the bulk phonon model. The effect of phonon confinement is important, especially for silicon thickness in the range 2-4 nm, where the bulk model predicted a significant mobility peak. The results obtained with free and rigid boundary conditions tend to approach each other when the thickness of the oxide layers grows, but when the thickness goes over 5-10 nm only small changes in the scattering rates are observed. Moreover, if both oxide layers are thick enough, the difference between the two disappears completely, while the difference with respect to the bulk model remains.