M.Sc. (Semester (CBCS) Examination Nov/Dec-2018
Electronic Science
SEMICONDUCTOR DEVICES
Time: 2½ Hours Max. Marks: 70
Instructions: All questions are compulsory.
Figures to the right indicate full marks.
Use of nonprogrammable calculator is allowed.
Q.1 Select the most correct alternative 14
materials has ppm levels of impurities.
Metallurgical grade Si Semiconductor grade Si
Electronic grade Si Both b and c
The electrical conductivity of semiconductor is the insulator.
equal to greater than
less than independent
SCR lamp control is used in of p-n junction fabrication.
diffusion Ion Implantation
RTP photolithography
Sharing of an electron in atoms is called
ionic bond covalent bond
metallic bond none of above
The implies that the carrier drift velocity is comparable to the
thermal velocity.
hot carrier effect chemical vapor deposition
Ebers -Moll model carrier drift
lattice structure is called zinc blende structure.
Simple cubic Body centered cubic
Face centered cubic Diamond
Band gap of silicon is at room temperature (T=300K).
0.67eV 1.1eV
2.42eV 5eV
is voltage-variable capacitance of a reverse biased p-n junction.
Varactor diode Tunnel diode
Zener diode None of the above
Ultimately due to the quantization of the charge on electrons and holes is

Johnson noise Shot noise
Avalanche noise All of the above
10) An electric field and Drift of holes are
in the opposite direction perpendicular to each other
in the same direction independent
11) The FET is a
majority carrier device minority carrier device
bipolar device all of the above
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SLR-VH-232
12) Miller overlap capacitance is the capacitance between
gate and drain gate and shield
gate and source source and shield
13) The thickness of epitaxial layer is less than the thickness of critical layer
is
homo junction junction tail
misfit dislocations pseudomorphic growth
14) If E EF, Fermi Dirac distribution is
low equal to Eg
high infinity
Q.2 Answer the following. (Any Four) 08
Explain FCC structure of crystal.
Define epitaxial growth.
Explain base narrowing.
What is extrinsic semiconductor?
Give a brief account of metallization.
Answer the following. (Any Two) 06
Light emitting diode
Effective mass of electrons
J-FET
Q.3 Answer the following (Any Two) 08
What is solar cell?
Define density of state. Calculate the density of states effective mass
of an electron in Si, if m1 0.98m0, mt= 0.19m0
Explain etching process of p-n junction fabrication.
Answer the following (Any One) 06
Explain Schottky barriers diode.
Explain Hall Effect and derive an expression for Hall coefficient
and Hall mobility
Q.4 Answer the following (Any Two) 10
Discuss semiconductor, metal and insulator with suitable sketch.
Distinguish between n-type and p-type semiconductors.
A Si sample is doped with 1017 As atoms/cm3. What is the equilibrium
hole concentration p0 at 300 Where is relative to
Answer the following (Any One) 04
Explain switching operation of BJT.
Explain tunnel diodes in brief.
Q.5 Answer the following (Any Two) 14
An abrupt Si p-n junction has Na=1018 cm-3 on one side and Nd=5X1015
cm-3 on the other;
Calculate the Fermi level position at 300K in the p and n regions
Draw an equilibrium band diagram for the junction and determine the
contact potential, V0.
Give brief explanation on thermal oxidation.
Explain MOSFET with suitable diagram.