Master of Science I (Electronic Sci.) Examination: Oct Nov 2016
Semester I (New CBCS)
SLR No. Day
Date Time Subject Name Paper
No. Seat No.
SLR SJ 332 Wednesday
16/11/2016
10.30 AM
to
01.00 PM
Semiconductor Devices
C
HCT 1.1
Instructions: All questions carry equal marks.
Q.1 and Q.2 are compulsory.
Attempt any THREE questions from Q.3 to Q.7
Use of non-programmable calculator is allowed.
Total Marks: 70
Q.1 Select the most correct alternative- 06
Package fraction of a is higher than the others.
Simple cubic Body centered cubic
Face centered cubic Diamond
Which type of material has impurities at the levels of several hundred to
several thousand parts per million
Metallurgical grade Si Semiconductor grade Si
Electronic grade Si Both and
have a positive effective mass.
Holes Electrons
Holes and electron both Neutrons
What is the equilibrium hole concentration at 300 if Si sample is doped
with As concentration of 1017 atoms/cm3?
1017cm-1 300 cm3
1.5 X 1020 cm-1 2.25 X 103 cm3
Junction between dissimilar semiconductors is
homo junction heterojunction
both homo and hetero
junction
junction tail
JFET is device.
voltage current
both voltage and current power
State whether following statements are true or false: 08
A unit cell allows lattice points not only at the corners, but also at the face
center.
Number of electrons and holes are equal in extrinsic semiconductors.
Semiconductor materials at 0 K have the same structure as insulators with
conduction and valence band.
Zener breakdown occurs at higher voltages compared to Avalanche.
Two-terminal devices designed to respond to photon absorption are called
photodiodes.
Patterns corresponding to complex circuitry are formed on a wafer using
etching process.
Schottky barrier devices are not suited for use in densely packed
integrated circuits.
Haynes-Shockley experiment is used to measure the minority carrier
mobility.
Q.2 Write brief notes on the following:
Give a brief account of molecular beam epitaxy. 05
Write a note on effective mass. 05
What are rectifying contacts? 04
Q.3 Calculate the areal density of Si atoms (number/cm2) on the plane.
Also calculate the volume density of Si atoms (number of atoms/cm3), the
lattice constant of Si is 5.43 A.
Calculate the maximum packing fraction and the radius of the atoms
treated as hard spheres with the nearest neighbors touching.
05
05
Write a note on Cubic lattices. 04
Q.4 What are intrinsic and extrinsic materials? 10
What is the law of mass action? Describe law of mass action for p-type and
n-type semiconductors.
04
Q.5 What is a rectifier? Give the advantage of guard ring diffusion. 10
Distinguish between diode and varactor diode? 04
Q.6 Derive an expression for current voltage characteristics of a FET. 10
Comment on the threshold voltage of an ideal MOS. 04
Q.7 What is Fermi level and the Fermi Dirac distribution function? Draw and
explain the Fermi-Dirac distribution function of intrinsic, n-type and p-type
material.
10
Explain Hall effect in brief. 04