The Field-Effect Tetrode

The new device described here consists basically of a thin Nregion adjacent to a comparably thin P region. Two contacts are made to the N side and two to the P side so that currents can be passed through each thin region parallel to the single junction of the device. The two currents do not mix because reverse bias is maintained on the junction. A current in either side affects the resistance of the other side, and hence the current in the other side, through the medium of the depletion layer; this mutual interaction of currents gives the device its unique properties. The field-effect tetrode has applications as a gyrator and isolator. In a two-terminal connection it exhibits voltage-controlled negative resistance. Also, it can be applied as a truly linear, yet electronically variable, resistor. Equations are developed for its behavior in these applications and experimental results are discussed. In the models to date, the thin regions were shaped by rather tedious mechanical and chemical procedures. Epitaxial film techniques may be well adapted to its fabrication in the future.