Name : …………………………………………….
………………
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Roll No. : …………………………………………...……………..
Invigilator’s Signature : ………………………………………..
CS/B.Tech (ECE-OLD)/SEM-3/EC-301/2012-13
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2012
SOLID STATE DEVICE
Time Allotted : 3 Hours Full Marks : 70
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The figures in the margin indicate full marks.
Candidates are required to give their answers in their own words
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as far as practicable.
GROUP – A
( Multiple Choice Type Questions )
1. Choose the correct alternatives for any ten of the following :
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10 × 1 = 10
i) Which type of semiconductor is mostly used for forming
transistor
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a) Si b) Ge
c) Inp d) GaAs.
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ii) Which type of capacitance is prominent in reversed bias
a) diffusion b) depletion
c) none of these d) both of these.
a c.
iii) Which one of the following provides fastest switching
a) BJT b) MOSFET
c) JFET d) Diode.
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iv) Which time is larger
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a) forward recovery time
b) reverse recovery time
c) vary time to time
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d) both are same.
v) Which current dominates when a pn junction is forward
baised
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a) drift current b) displacement current
c) diffusion current d) none of these.
vi) Input impedence is highest in which
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a) BJT b) JFET
c) MOSFET d) Diode.
vii) At '0' K The probability of getting electron with energy
E = EF is
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1 1
a) b)
2 4
c) 0 d) 1.
Where EF is the Fermi level energy band.
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viii) If temperature increasing zener break down voltage
a) increasing
b) decreasing
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c) independent of temperature
d) may increase or decrease.
ix) Whose mobility is higher
a c.
a) electron
b) hole
c) both have the same
d) sometime electron some time hole.
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CS/B.Tech (ECE-OLD)/SEM-3/EC-301/2012-13
x) The Varactor Diode is used in which bias
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a) forward
b) reverse
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c) both of these
d) sometime forward sometime reverse
xi) For an impure semiconductor electron concentration is
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4 ⋅ 5 ×1012 / cm3 & hole concentration 4 ×107 / cm3 ,
then position of Fermi level in equilibrium is
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a) at intrinsic level
b) inside valance band
c) close to conduction band
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d) close to valance band.
GROUP – B
( Short Answer Type Questions )
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Answer any three of the following. 3 × 5 = 15
2. State the basic steps of monolithic IC fabrication. What is
photolithography and how it is done in IC fabrication.
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3. Write short notes on solar cell.
4. Briefly explain the working principle of IMPATT Diode.
a c.
5. Explaiin rectiying contact and ohomic contact in the light of
Scottky Diode
6. Draw and explain the static characteristics of a JFEET.
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GROUP – C
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( Long Answer Type Questions )
Answer any three of the following. 3 × 15 = 45
7. Derive the expression for depetion region width in a pn
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junction diode. Is contact potential is measurable using
voltmeter ? What are the differences between zener
breakdown and avalanche breakdown ? 10 + 2 + 3
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8. Draw and explain the V-I characteristics of a tunnel diode.
Point out the negative differential resistance. Which
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semiconductors are mostly used for forming tunnel diode ?
What is the main condition for constructing tunnel diode ?
Mention any two applications of tunnel diode. What do you
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mean by indirect semi-conductor. 8+2+1+1+2+1
9. Draw the output characteristics of a CE mode npn transistor.
Why npn transistor is more used than pnp transistor. Write
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out two major applications of transistor. Is IC = βIB is true
for all three regions, if not then it is true for which region ?
10 + 1 + 2 + 2
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10. Derive the expression for pinch-off voltage in JFET. Explain
how channel is formed and current conduction takes place in
an Enhancement MOSFET. Define threhold voltage and flat
a c.
band voltage of MOSFET 6+6+3
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