JEE Questions for Physics Semiconductor Devices Quiz 11 - MCQExams.com

Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers would be
  • Positively charged
  • Negatively charged
  • Positively charged or negatively charged depending upon the type of impurity that has been added
  • Electrically neutral
If ne and vd be the number of electrons and drift velocity in a semiconductor. When the temperature is increased
  • ne increases and vd decreases
  • ne decreases and vd increases
  • Both ne and vd increases
  • Both ne and vd decreases
In extrinsic semiconductors
  • The conduction band and valence band overlap
  • The gap between conduction band and valence band is more than 16 eV
  • The gap between conduction band and valence band is near about 1eV
  • The gap between conduction band and valence band will be 100 eV and more
Based on the energy band description, a solid can be classified as a semiconductor if the energy gap between the valence band and conduction band is
  • 3eV < Eg < 6 eV
  • Eg > 6 eV
  • Eg < 3eV
  • Eg = 0 eV
The forbidden energy gap in Ge is 0.72 eV. Given, hc = 12400 eV–Å. The maximum wavelength of radiation that will generate electron hole pairs is
  • 172220 Å
  • 172.2 Å
  • 17222 Å
  • 1722 Å
Intrinsic germanium and silicon at absolute zero temperature behave like
  • Superconductor
  • Good semiconductor
  • Ideal insulator
  • Conductor
Solids having highest energy level partially filled with electrons are
  • Semiconductor
  • Conductor
  • Insulator
  • None of these
In a PN-junction diode
  • The current in the reverse biased condition is generally very small
  • The current in the reverse biased condition is small but the forward biased current is independent of the bias voltage
  • The reverse biased current is strongly dependent on the applied bias voltage
  • The forward biased current is very small in comparison to reverse biased current
The electrical circuit used to get smooth DC output from a rectifier circuit is called
  • Oscillator
  • Filter
  • Amplifier
  • Logic gates
What is the current through an ideal PN-junction diode show in figure below?
Physics-Semiconductor Devices-87803.png
  • Zero
  • 10 mA
  • 20 mA
  • 50 mA
The electrical resistance of depletion layer is large because
  • It has no charge carriers
  • It has a large number of charge carriers
  • It contains electrons as charge carriers
  • It has holes as charge carriers
The output form of a full wave rectifier is
  • An AC voltage
  • A DC voltage
  • Zero
  • A pulsating unidirectional voltage
If the forward voltage in a semiconductor diode is doubled, the width of the depletion layer will
  • Become half
  • Become one-fourth
  • Remain unchanged
  • Become double
When a PN-junction diode is reverse biased
  • Electrons and holes are attracted towards each other and move towards the depletion region
  • Electrons and holes move away from the junction depletion region
  • Height of the potential barrier decreases
  • No change in the current takes place
Two PN-junctions can be connected in series by three different methods as shown in the figure. If the potential difference in the junctions is the same, then the correct connections will be
Physics-Semiconductor Devices-87805.png
  • In the circuit 1 and 2
  • In the circuit 2 and 3
  • In the circuit 1 and 3
  • Only in the circuit 1
A PN-junction has a thickness of the order of
  • 1 cm
  • 1 mm
  • 10–6 m
  • 10–12 cm
On increasing the reverse bias to a large value in a PN-junction diode, current
  • Increases slowly
  • Remains fixed
  • Suddenly increases
  • Decreases slowly
In the case of forward biasing of PN-junction, which one of the following figures correctly depicts the direction of flow of carriers?

  • Physics-Semiconductor Devices-87806.png
  • 2)
    Physics-Semiconductor Devices-87807.png

  • Physics-Semiconductor Devices-87808.png

  • Physics-Semiconductor Devices-87809.png
A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be
  • A P-type semiconductor
  • An N-type semiconductor
  • A PN-junction
  • An intrinsic semiconductor
In a PN-junction diode not connected to any circuit
  • The potential is the same everywhere
  • The P-type is a higher potential than the N-type side
  • There is an electric field at the junction directed from the N-type side to the P-type side
  • There is an electric field at the junction directed from the P-type side to the N-type side
Which of the following statements is not true?
  • The resistance of intrinsic semiconductors decrease with increase of temperature
  • Doping pure Si with trivalent impurities gives P-type semiconductors
  • The majority carriers in N-type semiconductors are holes
  • A PN-junction can act as a semiconductor diode
In P - N junction, avalanche current flows in circuit when biasing is
  • Forward
  • Reverse
  • Zero
  • Excess
The depletion layer in the P-N junction region is caused by
  • Drift of holes
  • Diffusion of charge carriers
  • Migration of impurity ions
  • Drift of electrons
In a P-N junction diode if P region is heavily doped than n region then the depletion layer is
  • Greater in P region
  • Greater in N region
  • Equal in both region
  • No depletion layer is formed in this case
When NPN transistor is used as an amplifier
  • Electrons move from base to collector
  • Holes move from emitter to base
  • Electrons move from collector to base
  • Holes move from base to emitter
A junction diode has a resistance of 25Ω when forward biased and 2500 Ω when reverse biased. The current in the diode, for the arrangement shown will be
Physics-Semiconductor Devices-87811.png

  • Physics-Semiconductor Devices-87812.png
  • 2)
    Physics-Semiconductor Devices-87813.png

  • Physics-Semiconductor Devices-87814.png

  • Physics-Semiconductor Devices-87815.png
Zener breakdown in a semiconductor diode occurs when
  • Forward current exceeds certain value
  • Reverse bias exceeds certain value
  • Forward bias exceeds certain value
  • Potential barrier is reduced to zero
When forward bias is applied to a P–N junction, then what happens to the potential barrier VB and the width of charge depleted region x
  • VB increases, x decreases
  • VB decreases, x increases
  • VB increases, x increases
  • VB decreases, x decreases
The potential barrier, in the depletion layer, is due to
  • Ions
  • Holes
  • Electrons
  • Both (b) and (c)
When the P end of P–N junction is connected to the negative terminal of the battery and the N end to the positive terminal of the battery, then the P – N junction behaves like
  • A conductor
  • An insulator
  • A superconductor
  • A semiconductor
A potential barrier of 0.50 V exists across a P–N junction. If the depletion region is 5.0 × 10–7 m wide, the intensity of the electric field in this region is
  • 1.0 × 106 V/m
  • 1.0 × 105 V/m
  • 2.0×105 V/m
  • 2.0 × 106 V/m
If no external voltage is applied across P–N junction, there would be
  • No electric field across the junction
  • An electric field pointing from N-type to P-type side across the junction
  • An electric field pointing from P-type to N-type side across the junction
  • A temporary electric field during formation of P-N junction that would subsequently disappear
In the middle of the depletion layer of a reverse-biased PN junction, the
  • Potential is zero
  • Electric field is zero
  • Potential is maximum
  • Electric field is maximum
A crystal diode is a
  • Non-linear device
  • Amplifying device
  • Linear device
  • Fluctuating device
A bridge rectifier is shown in figure. Alternating input is given across A and C. If output is taken across BD, then it is
Physics-Semiconductor Devices-87819.png
  • Zero
  • Same as input
  • Half wave rectified
  • Full wave rectified
No bias is applied to a P - N junction, then the current
  • Is zero because the number of charge carriers flowing on both sides is same
  • Is zero because the charge carriers do not move
  • Is non-zero
  • None of the above
The width of forbidden gap in silicon crystal is 1.1 eV. When the crystal is converted into a N-type semiconductor the distance of Fermi level from conduction band is
  • Greater than 0.55 eV
  • Equal to 0.55 eV
  • Lesser than 0.55 eV
  • Equal to 1.1 eV
A semiconductor X is made by doping a germanium crystal with arsenic (Z = 33). A second semiconductor Y is made by doping germanium with indium (Z = 49). The two are joined end to end and connected to a battery as shown. Which of the following statements is correct?
Physics-Semiconductor Devices-87820.png
  • X is P-type, Y is N-type and the junction is forward biased
  • X is N-type, Y is P-type and the junction is forward biased
  • X is P-type, Y is N-type and the junction is reverse biased
  • X is N-type, Y is P-type and the junction is reverse biased
In P – N junction, the barrier potential offers resistance to
  • Free electrons in N region and holes in P region
  • Free electrons in P region and holes in N region
  • Only free electrons in N region
  • Only holes in P region
Symbolic representation of photodiode is

  • Physics-Semiconductor Devices-87821.png
  • 2)
    Physics-Semiconductor Devices-87822.png

  • Physics-Semiconductor Devices-87823.png

  • Physics-Semiconductor Devices-87824.png
To make a PN junction conducting
  • The value of forward bias should be more than the barrier potential
  • The value of forward bias should be less than the barrier potential
  • The value of reverse bias should be more than the barrier potential
  • The value of reverse bias should be less than the barrier potential
Which is the wrong statement in following sentences?
A device in which P and N-type semiconductors are used is more useful than a vacuum type bacause
  • Power is not necessary to heat the filament
  • It is more stable
  • Very less heat is produced in it
  • Its efficiency is high due to a high voltage across the junction
In the diagram, the input is across the terminals A and C and the output is across the terminals B and D, then the output is
Physics-Semiconductor Devices-87825.png
  • Zero
  • Same as input
  • Full wave rectifier
  • Half wave rectifier
The current through an ideal PN junction shown in the following circuit diagram will be
Physics-Semiconductor Devices-87826.png
  • Zero
  • 1 mA
  • 10 mA
  • 30 mA
In a full wave rectifiers, input AC current has a frequency ‘v’. The output frequency of current is
  • v/2
  • v
  • 2v
  • None of these
A diode having potential difference 0.5 V across its junction which does not depend on current, is connected in series with resistance of 20 Ω across source. If 0.1 A passes through resistance, then what is the voltage of the source?
  • 1.5 V
  • 2.0 V
  • 2.5 V
  • 5 V
In a reverse biased diode when the applied voltage changes by 1 V, the current is found to change by 0.5 µA. The reverse bias resistance of the diode is
  • 2 × 105 Ω
  • 2 × 106 Ω
  • 200 Ω
  • 2 Ω
Suppose an unregulated D.C. input voltage VI is applied to a Zener diode having breakdown voltage (VZ). Then, the breakdown condition for the diode to work as voltage regulator is
  • VI < VZ
  • VI = VZ
  • VI > VZ

  • Physics-Semiconductor Devices-87829.png
The energy of radiation emitted by LED is
  • Greater than the band gap of the semiconductor used
  • Always less than the band gap of the semiconductor used
  • Always equal to the band gap of the semiconductor used
  • Equal to or less than the band gap of the semiconductor used
Currents flowing in each of the circuits A and B respectively
Physics-Semiconductor Devices-87831.png
  • 1A, 2 A
  • 2 A, 1 A
  • 4A, 2 A
  • 2 A, 4 A
0:0:1


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