Metal-semiconductor field effect transistor device

Claim 1

A metal-semiconductor field effect transistor device, comprising: a semiconductor substrate having a main surface; an active layer formed at the main surface of the semiconductor substrate; source and drain electrodes formed on and in ohmic contact with the active layer and defining respective source and drain regions in the active layer, the source and drain electrodes being displaced in a first direction so as to define therebetween an exposed surface portion of the active layer and an active region of the active layer corresponding to the exposed surface portion thereof and extending in the first direction between the source and drain regions, the active region defining a controllable, conductive channel between the source and drain regions; a first gate electrode centrally disposed on the exposed surface of the active layer in Schottky contact therewith, the first gate electrode extending in a second direction, transverse to the first direction and thus to the conductive channel, and having substantially parallel, first and second edges respectively displaced from corresponding, opposed edges of the drain and source electrodes and thereby defining corresponding, first and second remaining segments of the exposed surface of the active layer; a second gate electrode comprising first and second portions on the respective, first and second remaining segments of the exposed surface of the active layer, extending in parallel relationship and respectively spaced from the respective first and second edges of the first gate electrode and the corresponding, opposed edges of the drain and source electrodes; each of the first gate electrode and the first and second portions of the second gate electrode having corresponding depletion regions associated therewith, extending into the active region of the active layer as a result of surface effects of the active layer and the respective Schottky contacts of the electrodes therewith; means for applying a constant voltage to the second gate electrode for suppressing the extension of the depletion regions corresponding thereto in the active region; and means for applying a variable input signal to the first gate electrode for correspondingly, variably controlling the extension of the corresponding depletion region associated therewith and correspondingly the level of conduction in the conductive channel.