Calicut University 2011-4th Sem B.Tech Electronics and Communications Engineering ec09 406-solid state devices - Question Paper

PART A
(5x2 Marks=10 Marks)

1.What is meant by low-level injection condition in semiconductors?

2.What is ohmic contact?

3.What is pinch-off voltage?

4.What is meant by transistor breakdown?

5.What are the various kinds of power diodes?

PART B
(4x5 Marks=20 MArks)

6.Derive the expressions for charge concentrations of semiconductor doped with both pentavalent and trivalent impurites.

7.Derive the operating point for a forward biased PN junction diode

8.With circuit diagram discuss and write the expressions for terminal currents in NPN BJT

9.Explain with circuit diagram how BJT act as a switch

10.Explain the substrate bias effects in MOSFET

11.Explain the short-channel effects in MOSFET

PART C
(4x10 Marks=40 Marks)

12.(a)Derive the expression for Fermi level in p-type semiconductor.

or

(b)Derive the expression for drift current in semiconductor in terms of charge concentrations.

13.(a)Derive the expression for diffusion capacitance in PN junction.

or

(b)Derive the PN junction diode current formula

14.(a)Explain with circuit diagram how transistor works with timing diagrams.

or

(b)Explain the working of n-channel JFET and its drain and transfer characterisitics.

15.(a)Explain with diagrams the working and characteristics of n-channel enhancement MOSFET

or

(b)Explain the operation of SCR with 2 transistor model and draw its characteristics.

Earning:   Approval pending.