Impact of substrate on the frequency behavior of trans-conductance in ultrathin body and BOX FDSOI MOS devices - A physical insight

The continuous reduction in the thickness of body and BOX of FDSOI MOS devices (to sustain scaling) have resulted in increased coupling between the top-gate and substrate underneath BOX. In this work, we have reported an increase in small signal trans-conductance (g<inf>m</inf>) with increase in frequency because of this coupling. This dependence is modulated by changing the substrate doping and BOX thickness. The physical mechanism responsible for this behavior is explained through measurement on different test structures and detailed device simulation.