Transistor width augmented effective gate semiconductor device having such a transistor and method of realization

The transistor (6) field effect transistor includes a region (2) of semiconductor material which forms a protrusion from a layer (5) of semi-conductive material. The gate electrode (3 ', 3 ") is separated from the region (2) projecting from a gate insulating material. The gate electrode (3', 3") covers a main wall of the zone (2 ) and projecting partially overlaps a side wall of the zone (2) projecting into a desired overlapping depth.