Tunnel Diode

Tunnel diodes are introduced by Leo Easaki in 1958, Which is high impurity concentrated device.Generally for a normal p-n junction diode imurity concentration of about 1 part in 10⁸ and its depletion region width is about 5 microns i.e. 5x10^-4 cm.In tunnel diode impurity concentration is increases upto 1 part in 10³ .

Tunneling: In a electronic device a particle must have an energy at least equal to the height of a potential barrier, if it is move from one side to the other.The Schrodinger equation indicates that there is a large probability that an electron will penetrates tjhrough the barrier.This quantum-mechanical behaviour is referred to as tunneling,and hence these high impurity-density p-n junction devices are called tunnel diodes.