We construct a tunnel diode oscillator (TDO) to study electromagnetic response of a superconducting thin film. This type of diode is also known as an Esaki diode [ 38 ], after the inventor, Leo Esaki, who discovered the effect in 1957, a discovery for which he was awarded the Nobel Prize in Physics in 1973. Its working is based on the tunneling effect. The construction of LED is similar to the normal p-n junction diode except that gallium, phosphorus and arsenic materials are used for construction instead of silicon or germanium materials. Germanium is the most commonly used material in Tunnel diode. Construction and Working of PN Junction Diode. Most widely used material for the construction of the Gunn diode is Gallium arsenide (GaAs), and Indium Phosphide (InP). TUNNEL DIODE TEST CIRCUITS PHOTOGRAPH OF PEAK CURRENT TEST SET UP FIGURE 7.9 7.3 Tunnel Diode Junction Capacitance Test Set In previous chapters the tunnel diode equivalent circuit has been analyzed and it can be shown that the apparent capacity looking into the device terminals is: strays - L s g d (when w <