0 02000EC203092001 Pages: 3

Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
Third Semester B.Tech Degree (S,FE) Examination December 2020 (2015 Scheme)

Course Code: EC203
Course Name: SOLID STATE DEVICES (EC, AE)
Max. Marks: 100 Duration: 3 Hours
PARTA
Answer any two full questions, each carries 15 marks. Marks

1 a) Define Fermi-Dirac distribution function. Explain each term in it. With the help (5)
of plots, characterize temperature dependence of this function.

b) Starting from fundamentals, derive an expression to calculate the intrinsic carrier (10)
concentration of semiconductors. What are the factors on which intrinsic carrier
concentration depends?

2 ஐ With suitable assumptions, derive Einstein’s relation for mobility of electrons in (7)
a semiconductor
b) A semiconductor is doped with 2x10'%cm? Boron atoms and 1x10'cm“of (8)
Phosphorus atoms at 300 K. Calculate
1) The type of the sample
ii) Electron and Hole concentrations
iii) The fermi level position with respect to intrinsic energy level
iv) Plot the energy band diagram indicating the band edges, Ey, Ej and the
band gap energy.
സ്സ 1.5x10!°cm® for Silicon at 300 K)
3 ஐ Derive one dimensional continuity equation for holes in a semiconductor. With (10)
suitable assumptions, obtain the diffusion equations for holes and electrons.

b) With suitable energy band diagram, explain the indirect recombination (5)

mechanism via traps.
PART ‏تا‎
‎Answer any two full questions, each carries 15 marks.
4 a) Plot the energy band diagram of a PN junction under (6)

i) Equilibrium 1) Forward bias iii) Reverse bias

Page 1 of 3