Test: Tunnel Diodes & Its Characteristics - Electrical Engineering (EE) MCQ

In forward bias, negative resistance helps for tunnel diode to operate. Here, the current decreases with increase in voltage. If they are used in reverse bias, they are called as back diodes. Avalanche diode operates in reverse bias at breakdown region.

In tunnel diode characteristics, the slope is negative in the region between V_Vand V_P. Here, it offers negative resistance. The characteristics are depicted below:

Tunnel diode is a type of semiconductor which works on tunneling effect of electrons in microwave region. So, tunnel diode has a very fast operation in microwave region.

The negative resistance property helps in the operation of tunnel diode. As the tunnel diode works at high frequency, its applications are mostly in that range. High frequency oscillators are based on the resonant tunneling diode.

When the P and N regions are very highly doped, the depletion layer comes closer. The tunnel diode is also highly doped. Its doping concentration varies within a small scale. So it’s an abrupt diode. For these reasons, the depletion region is small.

When the forward bias is increased, the tunnel current is also increased upto a certain limit. This happens when the electron movement takes place from P to N side.

Tunneling means a direct flow of electrons across small depletion region from N side conduction band to P side valance band. The electrons begin to accelerate in the N side of the semiconductor.

Germanium and silicon materials have low band gaps and flexibility. That matches tunnel diode requirements. The remaining materials emits the energy in terms of light or heat.

The carrier jump occurs without any loss of energy due to small depletion layer. The probability of the carrier to jump across a barrier depends on the energy and width of the band. This variess exponentially for a given carrier.

Anode goes through better heat dissipation. So the pellet is used for the purpose. The tindot via mesh screen resists inductive effects caused at the cathode. Conduction is an independent factor which can’t be controlled.