Influence of confined acoustic phonons on the electron mobility in ultrathin silicon-on-insulator layers

Abstract

We tried to reproduce experimental mobility curves for ultrathin silicon-on-insulator inversion layers using a Monte Carlo simulator and a bulk model for the electron scattering with acoustic phonons. We show that it is possible to reproduce the experimental behavior for the thicker samples. However, the acoustic phonon scattering rate is strongly underestimated when the thinnest samples are considered. The mobility curves for the thinnest samples can be reproduced using the same model if the sound velocity decreases as the silicon thickness decreases. This fact shows that acoustic phonons are also confined in ultrathin silicon on insulator inversion layers.