Extracting edge conduction around threshold in mesa-isolated SOI MOSFETs

•Aknee has been observed in the mesa isolated SOI pMOSFETs transfer characteristic.•The mesa isolation induces a presence of a parasitic transistor at the SOI pMOSFETs edges, which conducts earlier than the main transistor.•A methodology was presented to decompose edge and center contributions in mesa-isolated SOI pMOSFETs around threshold.•We revealed that the subthreshold regime is always driven by the edges. This work proposes a methodology to decompose the center and edge current contributions around threshold in mesa-isolated SOI MOSFETs using 3D TCAD simulations. Applied to pMOS measurements, it reveals that the subthreshold regime is driven by the active edge, whatever the device width. It also explains why the threshold voltage modulation by the back-gate bias depends on the device width, as well as why these effects are worse for high channel doping values.