MOS transistor and method of manufacturing

A method of fabricating a MOS transistor with a controllable and modulatable conduction path through a dielectric gate oxide is disclosed, wherein the transistor structure comprises a dielectric oxide layer (3) formed between two silicon plates (1,2), and wherein the silicon plates (1,2) overhang the oxide layer (3) all around to define an undercut (5) having a substantially rectangular cross-sectional shape. The method comprises the steps of: chemically altering the surfaces of the silicon plates (1,2) to have different functional groups (6,7) provided in the undercut (5) from those in the remainder of the surfaces; and selectively reacting the functional groups (6,7) provided in the undercut (5) with an organic molecule (8) having a reversibly reducible center and a molecular length substantially equal to the width of the undercut (5), thereby to establish a covalent bond to each end of the organic molecule (8).