Carrier Mobility Enhancement by Applying Back-Gate Bias in Ge-on-Insulator MOSFETs

In this letter, we comprehensively study the carriers’ mobility and the effect of back-gate bias (
${V} _{\textsf {bg}}$
) in Ge-on-insulator (GeOI) MOSFETs with various working modes, including accumulation mode (AM) nMOSFET, inversion mode (IM) nMOSFET, AM pMOSFET, and IM pMOSFET. The results show that the AM nMOSFETs and pMOSFETs have higher drain currents and carriers’ mobility. The electron mobility increases under positive
${V} _{\textsf {bg}}$
and decreases under negative
${V} _{\textsf {bg}}$
. While the hole mobility has the opposite
${V} _{\textsf {bg}}$
dependence. The carriers’ mobility of AM MOSFETs is proved to benefit more from
${V} _{\textsf {bg}}$
due to the increase of carriers’ densities. The peak mobility enhancements of more than 100% for holes and 35% for electrons are achieved in GeOI MOSFETs by applying
${V} _{\textsf {bg}}$
.