West Bengal Institute of Technology (WBIT) 2010-3rd Sem B.Tech Electronics and Communications Engineering WBUT,B-TECH,ESTER,SOLID STATE AND DEVICES(SSD)- - Question Paper
Thursday, 18 July 2013 02:25Web
GROUP-A (Multiple option kind Questions) Marks: 10×1=10 1. select the accurate options for any ten of the following:
i) Reverse saturation current of p-n junction diode is:
a) diffusion current b) drift current c) displacement current d) none of these
ii) Tunnel diode is used in
a) microwave oscillator b) r.f. oscillator c) audio oscillator d) video amplifier
iii) Electron effective mass depends on
a) curvature of band b) band gap c) doping concentration d) temperature
iv) Ion implantation is done
a) at lower temperature compared to diffusion b) at higher temperature compared to diffusion c) at most identical temperature as diffusion d) none of these
v) A varactor diode is operated under
a) reverse bias b) forward bias c) without bias d) zero bias
vi) Which of the subsequent has a negative resistance region
a) Zener diode b) Tunnel diode c) Photodiode d) LED
vii) In GaAs when the electron rises from central valley to satellite valley, the effective mass of the electron becomes
a) less b) more c)zero d) infinity
viii) The doping level of the emitter level of a transistor is
a) greater than the collector and the base regions b) less than the collector and base regions c) less than base region but greater than collector region d)greater than base region but less than collector region.
ix) When a positive voltage is applied to an n-type semiconductor with respect to the metal, the barrier ranging from the semiconductor and the metal
a) increases b) reduces c) remains same d) none of these
x) We can connect photodetector diode in
a) both in forward and reverse bias b) forward bias c) reverse bias d) no need to connect in any bias
xi) Flat band condition in an MOS capacitor occurs when
a)fs =0 b) f s > 0 c) f s < 0 d) f s = f F
xii) Inversion layer in an MOS device can be created by
a) doping b) impact ionization c) tunneling d) electric field
xiii) In photodiode, E-H pairs ase generated, when the energy of incident photon should be
a) hf < Eg b) hf > Eg c) hf = Eg d) hf >> Eg.
xiv) Solar cell operates in
a) first quadrant of I-V chart b) fourth quadrant of I-V chart c) second quadrant of I-V chart d) third quadrant of I-V chart.
xv) Avalanche breakdown primarily depends on the phenomenon of
a) impact ionization b) field ionization c) particle ionization d) impurity ionization.
GROUP--B (Short ans kind Questions)
ans any 3 of the subsequent questions:- 3 ×5 =15
2. Sketch the ideal energy band diagram oa metal semiconductorjunction when f M
4. a) describe step graded junction and linearity graded junction.
b) describe diffusion capacitance and transition capacitance.
5. What is degenerate semiconductor? Draw the volt-ampere characteristics of tunnel diode and discuss the occurrence of negative differential resistance in characteristics.
6 . What is Earlt effect? describe punch through in early effect.
GROUP—C (Long ans kind Questions) ans any 3 of the following: 3 ×5 =15
7. a) What is photovoltaic effect?
b) Write down the operating principle of solar cell. Derive the expression for V.
c) elaborate quantum efficiency and responsivity? Marks: two +3+10.
8. a) Draw the basic structures of a learn diode and explain the basic principles of the operation of IMPATT diode.
b) discuss transferred electron mechanism of the bulk negative differential conductivity exhibited by Gunn diode and mention irs applications. Marks: 7+ 8.
9. a) Sketch the energy band diagram of a MOS capacitor with an n-type substrate in accumulation, depletion and inversion modes.
b) What is the total capacitance of an MOS capacitor? ? How does it vary with voltage?
c) Derive an expression for threshold voltage of an ideal MOSFET. Marks:5+4+6.
10. a) Derive the expression for the current flowing across a p-n junction.
b) describe diffusion capacitance and storage capacitance in p-n junction. Marks:10+5.
11. Write short notes on any 3 of the following: Marks: 3×5
a) Varactor diode
b) Miller indices
c) Photolithography
d) Voltage Regulator Circuit
e) Schottky barrier diode.
| Earning: Approval pending. |
