Background: I have a circuit for a FGMOS and they are describing the Fowler-Nordheim Tunneling (FNT) mechanism. The picture features two transistors: the main (FG)MOS and a secondary MOS to encapsulate the FNT mechanism. The MOSFET responsible for FNT has the Drain, Source and Bulk all connected to a source, V_Tunn. The gate of this transistor is then connected to the gate of the (FG)MOS.
Image source: Ochoa-Padilla et. al. Floating-Gate MOS Charge Programming Using Pulsed Hot-Electron Injection. Oct. 2013.
Question: Why is the MOSFET connected this way? Does this make the FNT MOSFET act as a Two-Terminal Semiconductor/diode? See the attached picture.