How does a junction-less transistors work?
MOSFET as pictured was invented well before 2000, perhaps you mean MESFET , which is basically a JFET with the junction being instead a Schottky barrier

see https://en.wikipedia.org/wiki/MESFET that page says 2009 on the earliest reference.

JFETs and MESFETs work on the same principle the gate terminal can repel the charge 
carriers electrostatically out of the channel, when the channel is starved of charge carriers the device can't pass much current and behaves as a high resistance (or an insulator), it it has many it behaves as a low resistance.