Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 3rd Semester (Third Semester) 2015-2016 NEC 302 Fundamental Of Electronic Devices Question Paper
(Following Paper ID and Roll No. to be filled in your
Answer Book)
. Roll No.
B.Tech.
(SEM. III) THEORY EXAMINATION. 2015-16
FUNDAMENTAL OF ELECTRONIC DEVICES
[Time:3 hours] 4 [Total Marks:100]
Section-A
1. Attempt all parts. All parts carry equal marks. Write
answer of each part in short. (10X2=20)
(a) Differentiate Zener and avalanche mechanism on 7
? the basis of doping, voltage and required depletion
region width and ionization effect.
(b) Si sample is doped with 1020 As atoms/cm3. What
is equilibrium concentration of holes at 300K?
Where is Ef relative to Hi? Draw the energy band
diagram to show the position of Ei and Er Take
ni =1.5><10'0 cm?3.
(c) What is indirect band gap semiconductors.
(d) What is lattice scattering.
10000 , I (1) P.T.Or
Attempt any ?ve questions from this section:
2.
10000 , (2)
(e) How high electron mobility channel is created in
HEMI?
(f) Which semiconductor parameters are measured
? from Hall effect.
(g) State the principle of Invariance of Fermi level.
(h) What is superiority of metal semiconductor diode
over conventional diode?
(i) Why 3rd quadrant is preferred for photo detectors?
G) What is ?gure of merit of photodiode?
s Section-B
(5x10=50)
Calculate packing fraction and formation (with F CC) of
Si-unit cell. Also describe the energy band splitting in
Si crystal formation.
Discuss the temperature dependence of Fermi-Dirac
distribution function for semiconductor materials.
Derive the thermal equilibrium concentration of
electron.
Describe diffusion of carriers and derive the current
equation resulting due to this phenomenon. Also, derive
the Einstein relation.
NEC-302
A semiconductor sample is exposed to a photonic
excitation for a long time(t<0). Under low level
injection, derive the equation governing the decay of
excess carrier and life time of carrier if the excitation
is removed at t=0.
Derive the expression of contact potential for PN
homojunction?diode. Boron is implanted into an n-type
Si sample (N ?=10?6c1n?3), forming an abruptjunction of
square cross section with area=2><10" cmz. Assume
acceptor concentration in p-type region is N?=4><1018
cm". Calculate V0 Q?, 130 and depletion region extension
on either side of junction at RT. (Given ni=1.5><10lo
cm", 8, =11.8, 60 = 835x10-? F/cm and KT=0.0259
eVatRT).
Describe in detail the operation of n-channel
enhancement MOSFET. Draw is physical structure and
I-V characteristic.
With the help of neat diagram describe the operation of
Impact ionization avalanche transit time diode.
Deduce the conditions of lasing. Describe the operation
of semiconductor LASER.
10000 (3) P.T.O.
Section-C
Attempt any two question in this section : (2X15=30)
10. Mention ideal 1y desired characteristics of (parameters)
area, doping, lifetime and width of base region in BJT.
With the help of neat diagram showing the various current
components of a PNP BJT, describe emitter injection
ef?ciency, base transport factor and collector to base
ampli?cation ratio. Describe how the base current
controls the operation 9fBJT.
ll. Derive the ideal diode equation. Discuss the majority
carrier ?owmechanism in neutral regions.
12. With the help two n'ansistor?analogy explain the operation
of PNPN diode. Also describe various turn-on
mechanisms used in SCR.
?X?
10000 t t (4) NEC-302
This post was last modified on 29 January 2020