p-n Junction

If the two ends of a p-n junction are joined by a wire,

The current−voltage characteristic of an ideal p-n junction diode is given by \[i =  i_0 ( e^{eV/KT}  - 1)\] where, the drift current i₀ equals 10 µA. Take the temperature T to be 300 K. (a) Find the voltage V₀ for which \[e^{eV/kT}  = 100 .\]One can neglect the term 1 for voltages greater than this value. (b) Find an expression for the dynamic resistance of the diode as a function of V for V > V₀. (c) Find the voltage for which the dynamic resistance is 0.2 Ω.

(Use Planck constant h = 4.14 × 10^-15 eV-s, Boltzmann constant k = 8·62 × 10^-5 eV/K.)

Calculate the current through the circuit and the potential difference across the diode shown in figure. The drift current for the diode is 20 µA.

A semiconducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. the device may be
(a) an intrinsic semiconductor
(b) a p-type semiconductor
(c) an n-type semiconductor
(d) a p-n junction

Consider a p-n junction diode having the characteristic \[i -  i_0 ( e^{eV/kT}  - 1) \text{ where }  i_0  = 20\mu A\] . The diode is operated at T = 300 K . (a) Find the current through the diode when a voltage of 300 mV is applied across it in forward bias. (b) At what voltage does the current double?

Find the equivalent resistance of the network shown in figure between the points A and B.

(Assume that the resistance of each diode is zero in forward bias and is infinity in reverse bias.)

How is a zener diode fabricated so as to make it a special purpose diode? Draw I-V characteristics of zener diode and explain the significance of breakdown voltage.

Explain briefly, with the help of a circuit diagram, how a p-n junction diode works as a half wave rectifier.