Investigation of series resistances, interface coupling and irradiation effects on the transconductance of fully-depleted SOI-MOSFETs

The operation of fully-depleted silicon-on-insulator (SOI) MOS transistors is far more complex than in bulk Si MOSFETs due to a strong coupling between the front and back interfaces. This means that the front channel current can substantially be influenced by the back gate bias and vice-versa. The authors propose a dual-channel transconductance model which depicts and clarifies various experimental situations. It is concluded that the different effects, i.e., interface coupling, short-channel, series resistances, and irradiation, are interacting in SOI. The series resistance influence is enhanced when the back channel is activated either by increasing the substrate bias or by irradiation. The interest of the above model is two-fold: to describe the transconductance behavior by sorting out the different effects and to show how the interface parameters of thin SOI structures can be evaluated