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14 Semiconductor

The document contains a series of multiple-choice questions related to semiconductor physics, including topics such as the properties of intrinsic and extrinsic semiconductors, p-n junctions, rectification efficiency, and energy bands. Each question presents options for answers that cover fundamental concepts in semiconductor theory. The content is structured as a quiz format, likely for educational purposes.

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shivanantham m
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28 views2 pages

14 Semiconductor

The document contains a series of multiple-choice questions related to semiconductor physics, including topics such as the properties of intrinsic and extrinsic semiconductors, p-n junctions, rectification efficiency, and energy bands. Each question presents options for answers that cover fundamental concepts in semiconductor theory. The content is structured as a quiz format, likely for educational purposes.

Uploaded by

shivanantham m
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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1. C, Si and Ge have same no.of valence electrons.

C is an insulator because energy required to


take one electron out from
(a) Si is more (b) C is more (c) Ge is more (d) C is less
2. By adding _________ impurity in intrinsic semiconductor, p-type semiconductor is made.
Charge of these p type semiconductor is____
(a) Trivalent, neutral (b) Pentavalent, neutral (c) Pentavalent, positive(d) Trivalent, negative
3. Why can’t we physically join p-type and n-type semiconductor directly to form a p-n
junction?
(a) Inter-atomic spacing become less than 1A o (b) p-type will repet N-type
(c)There will be discontinuity for the following charge carriers
(d) Semi-conducting properties will be lost
4. which statement is incorrect regarding for p-n junction.
(a) Donar atoms are depleted of their holes in junction(b) No net charge exists far from junction
(c) Barrier potential V B is generated
(d) Energy V B is to be surmounted before any charge can flow across junction
5. The intrinsic semiconductor has
(a) A finite resistance which does not change with temperature
(b) Infinite resistance which decreases with temperature
(c) Finite resistance which decreases with temperature
(d) Finite resistance which does not change with temperature
6. The energy level just above the valence band is called ___ level
(a) Donar (b) Acceptor (c) ground (d) Conduction
7. The half of the a.c. signal is rectified it is a _____
(a) half wave (b) full wave (c) voltage (d) bridge
8. Efficiency of half wave rectifier is approximately ____
(a) 60.4 % (b) 40.6 % (c) 46 % (d) 60 %
9. Efficiency of full wave rectifier is approximately ____
(a) 82.1 % (b) 81.2 % (c) 80.2 % (d) 81.3 %
10. To remove d.C. voltage fluctuations we use ____
(a) filter circuits (b) sieve circuits (c) conductor circuits (d) rectifier circuits
11. Zener breakdown is mainly due to____
(a) collision (b) breaking of covalent bonds (c) doping (d) recombination
12. In a junction transistor the emitter region is heavily doped since emitter has to supply to the
base Zener diode acts as a
(a) minority carrier (b) majority carrier (c) acceptor ions (d) donar ions
13. In the output characteristics, the ohmic region is called
(a) saturation region (b) cut-off region (c) active region (d) breakdown region
14. Reverse bias applied to a junction diode
(a) increases the potential energy (b) increases the majority carrier current
(c) lowers the potential barrier (d) increases the minority carrier current
15. Zener diode is used for
(a) rectification (b) amplification (c) producing oscillation (d) stablisation
16. The energy band gap is maximum is
(a) metals (b) insulators (c) semiconductor (d) superconductors
17. A pure semiconductor behaves slightly as a conductor at
(a) low temperature (b) high temperature (c) room temperature (d) zero degree
18. If the distance between the conduction band and valence band is 1 ev, then this
combination is
(a) semiconductor (b) metal (c) insulator (d) conductor
19. In an insulator the energy gap between the conduction band and valence band is of the
order of
(a) 2 MeV (b) 5 eV (c) 1 eV (d) 10 -3 eV
20. In a good conductor the forbidden energy gap between the conduction band and valence
band is the order of
(a) infinity (b) zero (c) narrow (d) wide
21. Diffusion of free electrons across the junction of an unbiased diode produces
(a) forward bias (b) reverse bias (c) depletion layer (d) breakdown
22. Resistance of a semiconductor is ___ to temperature change
(a) directly proportional (b) indirectly proportional (c) a constant (d) independent
23. A set of closely packed energy level is called ____
(a) cluster (b) energy bands (c) constellation (d) energy pack
24. Atomic number of Si is
(a) 14 (b) 12 (c) 16 (d) 18
25. completely filled energy levels are called ____
(a) core levels (c) compound levels (c) conduction levels (d) valence levels
26. Vacant energy levels are called ___
(a) valence level (b) Core level (c) conduction levels (d) compound level
27. Partially filled outermost is called __
(a) valence level (b) core level (c) ground level (d) conduction level
28. ____ electrons occupy the conduction band,
(a) Ground state (b) Free (c) Bound (d) Valence
29. Energy gap between valence band and conduction band is called as the ____
(a) forbidden energy gap (b) conduction energy gap (c) valence band gap (d) filled energy gap
30. The forbidden energy gap is largest in
(a) conductor (b) metals (c) semiconductor (d) insulators\
31. a hole is _____ in charge
(a) neutral (b) negative (c) positive (d) charge depends on the type of semiconductor
32. Pure semiconductors are called___
(a) extrinsic semiconductor (b) intrinsic semiconductor (c) simple semiconductor (d) charged
semiconductor
33. Doped semiconductors are___
(a) extrinsic (b) intrinsic (c) simple (d) charged
34. When a pentavalent impurity is added to a pure semiconductor, we get ____
semiconductor
(a) N-type (b) P-type (c) A-type (d) B-type

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