SRM University 2007 B.Tech Electronics and Communications Engineering BANK ELECTRONIC DEVICES - Question Paper

10.Explain about:
a) Donor atoms
b) Acceptor atoms
c) Intrinsic semiconductors
d) N-type Extrinsic Semiconductor
e) P-type semiconductor
11. discuss about:
a) Valence shell
b) Valence electron
c) Free electrons
d) Holes
e) Covalent bond with suitable diagram























UNIT-II

PART-A



1. What is meant by photoconductivity?
2. Explain cutin voltage of a diode.
3. What is Zener breakdown?
4. Give a few applications of varactor diode and its symbol.
5. Sketch the VI characteristics of a tunnel diode.
6. State the relative merits of pin photodiodes and avalanche photodiodes.
7. The leakage current of a PN diode is caused by ____________.
8. Define DC (or) Static resistance (RF).
9. Define AC (or) Dynamic resistance (rF).
10. How is depletion region formed?
11. Give the advantages of using LCD over LED.
12. Draw the circuit model for Zener diode.
13. Avalanche breakdown is primarily dependent on the process of ____________.
14. What happens when a p-type material is joined with n-type material?
15. Draw the VI characteristics of LED.
16. The cutin voltages of a Germanium and silicon diodes are ____________.
17. The transition capacitance is also called as __________.
18. Varactor diode is realized with ________ bias provided to a junction diode.
19. Define barrier potential.
20. What is “tunneling”?
21. What are the uses of photodiode?
22. State photovoltaic effect.
23. What are the advantages in using cadmium sulphide as semiconductor material in LDR?
24. Draw the symbol for thermistor.
25. The reverse saturation current of silicon PN junction diode is 10?A. compute the diode current for the forward bias voltage of 0.6V at 25degree C.
26. What is a PN junction? How it is formed?
27. Explain how a barrier potential is developed at the PN junction.
28. discuss avalanche break down & zener breakdown.
29. describe leakage current. What is the advantage of silicon over germanium?
30. Explain VARACTOR diode and application.
31. describe PHOTODIODE.
32. Advantages and disadvantages of TUNNEL DIODE.
33. What is a PIN diode?
34. Write the Diode formula how can this be approximated?
35. How is Photodiode various from PhotoVoltaic Cell?










PART-B

1. Draw the energy band diagram of a PN junction and discuss the working of diode.

Earning:   Approval pending.