GUNN DIODES

A Gunn diode is made from a compound known as gallium arsenide (GaAs). When a voltage is applied to this device, it oscillates because of the Gunn effect, named after J. Gunn of International Business Machines (IBM), who first observed the phenomenon in the 1960s. Oscillation occurs as a result of a property called negative resistance. This is a misnomer because, as we have learned, there is no such thing as a device that conducts better than perfectly. In this sense, negative resistance refers to the fact that over a certain limited portion of the characteristic curve, the current through a Gunn diode decreases as the voltage increases, contrary to what normally takes place in electrical systems.