problem 1:

a) What do you mean by the term potential energy barrier of the p-n junction? How does it arise and what is its order of magnitude?

b) Sketch the V-I characteristics of p-n junction diode for forward bias voltages. Differentiate between the incremental resistance and the apparent resistance of the diode.

problem 2:

a) Describe in detail, the reason for exponential rise in forward characteristic of a diode with appropriate mathematical expression.

b) Describe in detail, the variation of given semiconductor parameters with temperature, Energy gap and Conductivity.

problem 3:

a) Derive an expression for total diode current beginning from Boltzmann relationship in terms of the applied voltage.

b) The reverse saturation current of a silicon p-n function diode at an operating temperature of 27⁰C is 50 nA. find out the dynamic forward and reverse resistances of the diode for applied voltages of 0.8 V and -0.4 V correspondingly.

problem 4:

a) Describe the operation of silicon p-n junction diode and obtain the forward bias and reverse bias Volt-Ampere characteristics.

b) Obtain the transition capacitance CT of a junction diode at a reverse bias voltage of 12 V if CT of the diode is given as 15 PF at a reverse bias of 8 V. Distinguish between transition and diffusion capacitances.

problem 5: Distinguish between:

a) Static and dynamic resistances of a p-n diode.
b) Transition and Diffusion capacitances of a p-n diode.
c) Volt-Ampere characteristics of a single silicon p-n diode and two identical silicon p- n diodes joined in parallel.
d) Avalanche and zener break down mechanisms.

problem 6:

a) Define the given terms for PN diode

•    Dynamic resistance
•    Load line
•    Difference capacitance
•    Reverse saturation current

b) A reverse bias voltage of 90V is applied to a Germanium diode via a resistance R. The reverse saturation current of the diode is 50 µA at an operating temperature of 25⁰C. find out the diode current and voltage for:

i) R = 10 MΩ
ii) R = 100 KΩ