PG – 673

*PG673*

I Semester M.Sc. Degree Examination, January 2015 (CBCS) ELECTRONIC SCIENCE ELC-101 : Physics of Semiconductor Devices Time : 3 Hours

Max. Marks : 70

Instructions : 1) Section A : Answer all questions. Each question carries 2 marks. 2) Section B : Answer any four full questions. SECTION – A

(2×5=10)

1. Give the comparison of crystal growth from melt and epitaxial growth methods. 2. Define mobility and give its units. 3. Explain the significance of band diagram of a p-n junction at equilibrium. 4. Explain the fabrication of BJT. 5. Define pinch off voltage of FET. SECTION – B

(4×15=60)

6. a) Explain the bonding forces in solids.

5

b) With necessary diagram explain the float zone process for the growth of a crystal.

10

7. a) Define law of mass action. Show that in an intrinsic semiconductor the product of electron and hole concentrations is independent of the position of the Fermi level. 10 b) Define Hall effect. Explain its importance.

5

8. a) With neat diagram explain the construction and working of varactor diode and list applications. b) Give the construction of photodiode and explain the photovoltaic and photoconductive modes of operation of photodiode.

5 10

P.T.O.

PG – 673

-2-

*PG673*

9. a) Describe the Ebers-Moll model of BJT and derive the Ebers-Moll equations for the emitter and collector currents of BJT. b) List the secondary effects of BJT and explain their importance.

5

10. a) Give the constructional details of GaAs MOSFET and draw its output characteristics.

7

b) Define threshold voltage of MOSFET and derive the equation of threshold voltage. 11. Write short notes on any three : i) Crystal properties of semiconductor ii) Kronig-Penney model of energy band theory iii) Light emitting diodes iv) Avalanche breakdown in transistor v) MOS capacitor. ———————

10

8

(3×5=15)