In this paper, we present a comprehensive experimental characterization of electron and hole effective mobility (μeff) of ultrathin SOI n- and p-MOSFETs. Measurements have been performed at different temperatures using a special test structure able to circumvent parasitic resistance effects. Our results indicate that, at large inversion densities (Ninv), the mobility of ultrathin SOI transistors is largely insensitive to silicon thickness (TSI) and is larger than in heavily doped bulk MOS because of a lower effective field. At small Ninv, instead, mobility of SOI transistors exhibits a systematic reduction with decreasing TSI. The possible explanation for this μeff degradation in extremely thin silicon layers is discussed by means of a comparison to previously published experimental data and theoretical calculations. Our analysis suggests a significant role is played by an enhancement of phonon scattering due to carrier confinement in the thinnest semiconductor films. The experimental mobility data have then been used to study the possible implications for ultrashort SOI transistor performance using numerical simulations.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering
- SOI MOSFETs
- SOI performance
- Ultrathin silicon films