Impact of Back-Gate Modulation on High Normal Field Mobility in Extremely-Thin-Body SOI pMOSFETs

In this study, the back-gate modulation of extremely-thin-body (ETB) silicon-on-insulator (SOI) pMOSFETs with channel thicknesses of 1.9 and 8.7 nm has been experimentally investigated. It is found that both positive and negative back-gate voltages (VBG) degrade the high normal-field hole mobility in 1.9-nm-thick ETB SOI pMOSFETs. However, in the case of 8.7-nm-thick devices, this mobility can be enhanced with larger negativeVBGor suppressed with larger positiveVBG. These phenomena can be attributed to the different carrier scatterings from the front and back MOS interfaces at different SOI thicknesses. Further TCAD simulations were performed to confirm thatVBGmodulation does not contribute to the enhancement of high normal field hole mobility in SOI pMOSFETs with a channel thickness below 2 nm. These findings offer a comprehensive understanding of carrier transport behaviors in ETB SOI pMOSFETs, providing valuable insights for the further development of nanosheet (NS) applications.