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N-Type Semiconductor Quiz
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N-Type Semiconductor Quiz

Created by
@SupportiveEpic5775

Questions and Answers

What is the primary characteristic of an n-type semiconductor?

  • It has an excess of free electrons. (correct)
  • It is made purely of silicon without impurities.
  • It contains holes as the majority charge carriers.
  • It has a higher valence electron count than silicon.

    • What role do pentavalent impurities play in n-type semiconductors?

  • They donate free electrons to the semiconductor. (correct)
  • They absorb excess electrons from the semiconductor.
  • They create holes in the semiconductor.
  • They increase the temperature of the semiconductor.

    • Which of the following is an example of a pentavalent impurity that can create an n-type semiconductor?

  • Gallium
  • Silicon
  • Boron
  • Arsenic (correct)

    • What happens to the 5th valence electron from an arsenic atom when added to silicon?

    <p>It becomes free and contributes to conduction.</p> Signup and view all the answers

    What term is used to describe the impurities that create n-type semiconductors?

    <p>Donor impurities</p> Signup and view all the answers

    In energy band diagrams, where do free electrons reside in an n-type semiconductor?

    <p>Conduction band</p> Signup and view all the answers

    How does the addition of arsenic affect the electronic structure of silicon?

    <p>It introduces additional free electrons.</p> Signup and view all the answers

    What is the most significant effect of adding pentavalent impurities to pure silicon?

    <p>It enhances the electrical conductivity of the semiconductor.</p> Signup and view all the answers

    What happens to the unbonded valence electrons of pentavalent impurities at room temperature?

    <p>They easily jump into the conduction band.</p> Signup and view all the answers

    Where is the donor energy level (ED) located in relation to the conduction band (Ec)?

    <p>Below the conduction band.</p> Signup and view all the answers

    What effect does a large number of free electrons have on the Fermi level in n-type semiconductors?

    <p>It shifts the Fermi level upwards.</p> Signup and view all the answers

    What occurs when an acceptor impurity is added to an intrinsic semiconductor?

    <p>Holes are created in the valence band.</p> Signup and view all the answers

    Where is the acceptor energy level (EA) located in relation to the valence band energy level (Ev)?

    <p>Above the valence band.</p> Signup and view all the answers

    What is the primary role of acceptor impurities in semiconductors?

    <p>To create holes by accepting valence band electrons.</p> Signup and view all the answers

    In an n-type semiconductor, what happens to the free electrons when they occupy energy levels towards the conduction band?

    <p>They contribute to electrical conductivity.</p> Signup and view all the answers

    What does a shift in the Fermi level towards the conduction band imply for an n-type semiconductor?

    <p>The number of free electrons increases.</p> Signup and view all the answers

    What does the polarity of Hall voltage indicate in semiconductors?

    <p>The type of semiconductor (P-type or N-type)</p> Signup and view all the answers

    Which of the following is NOT an application of the Hall effect?

    <p>Measuring thermal conductivity</p> Signup and view all the answers

    How long does an electron exist in the free state on average before recombination?

    <p>For τn seconds</p> Signup and view all the answers

    What is a p-n junction commonly referred to as?

    <p>Semiconductor diode</p> Signup and view all the answers

    What happens when free electrons from the n-type semiconductor diffuse to the p-type side?

    <p>Positive charge is built on the n-side</p> Signup and view all the answers

    In a pure semiconductor, what is the relationship between holes and electrons?

    <p>There are equal numbers of holes and electrons</p> Signup and view all the answers

    What is the formula for power input (Pac) in the given context?

    <p>Pac = I^2 * (rf + RL)</p> Signup and view all the answers

    What is the maximum efficiency of the rectifier when rf is negligible compared to RL?

    <p>40.6%</p> Signup and view all the answers

    What does 'carrier lifetime' refer to in semiconductors?

    <p>The average time electrons or holes exist in the free state</p> Signup and view all the answers

    In finding the rms current (Irms), which of the following is used?

    <p>Irms = (1/2π) ∫(Im Sinθ) dθ</p> Signup and view all the answers

    What is the role of thermal agitation in a pure semiconductor?

    <p>It produces new hole-electron pairs</p> Signup and view all the answers

    What characteristic defines a bridge rectifier compared to a center tapped full-wave rectifier?

    <p>Does not require a center tapped transformer</p> Signup and view all the answers

    Which relationship indicates the efficiency (η) of the rectifier in terms of Pac and Pdc?

    <p>η = Pdc / Pac</p> Signup and view all the answers

    What simplification can be made to achieve maximum rectifier efficiency?

    <p>Neglect RF in comparison to RL</p> Signup and view all the answers

    Which statement about the current flowing through the diode is correct?

    <p>Current flows through the diode only for the duration 0 to π.</p> Signup and view all the answers

    What is the relationship between I_m and I_rms as derived from the calculations?

    <p>I_rms = rac{I_m}{2}</p> Signup and view all the answers

    What is the peak-inverse voltage of a p-n junction?

    <p>The highest reverse voltage that can be applied without damage</p> Signup and view all the answers

    What occurs when the reverse voltage across a diode exceeds its peak-inverse voltage?

    <p>The junction gets destroyed due to overheating</p> Signup and view all the answers

    What is the maximum forward current in the context of a p-n junction?

    <p>The instant current that can be passed without damage</p> Signup and view all the answers

    In a half-wave rectifier, what is the role of the transformer?

    <p>To step-down the supply voltage and prevent shocks</p> Signup and view all the answers

    What happens during the positive half cycle of a half-wave rectifier?

    <p>The end X of the secondary becomes positive, forward biasing the diode</p> Signup and view all the answers

    What is meant by maximum power rating in a p-n junction?

    <p>The maximum power that can be dissipated without damage</p> Signup and view all the answers

    Which of the following statements about rectifiers is true?

    <p>Both half-wave and full-wave rectifiers convert AC to DC</p> Signup and view all the answers

    Which waveform best represents the output from a half-wave rectifier?

    <p>A pulsating DC waveform</p> Signup and view all the answers

    Study Notes

    n-Type Semiconductor

    • n-Type semiconductors are formed by adding pentavalent impurities to a pure semiconductor.
    • Common pentavalent impurities include Arsenic, Antimony, and Phosphorus, known as donor impurities because they provide free electrons.
    • Silicon, with 4 valence electrons, bonds with a pentavalent impurity's 4 valence electrons, leaving one free electron from the impurity.
    • At room temperature, most free electrons become available for conduction by jumping into the conduction band.
    • The donor energy level (ED) is just below the conduction band (Ec), influencing the Fermi level (Ef) to shift upward towards the conduction band.

    p-Type Semiconductor

    • p-Type semiconductors are created by adding acceptor impurities to intrinsic semiconductors.
    • Acceptor energy levels (EA) are close to the valence band (Ev), allowing valence band electrons to create holes in the valence band.
    • The Fermi level (Ef) is situated between the valence band and the acceptor energy level, indicating the presence of holes.

    Hall Effect Applications

    • The Hall effect is used to determine various semiconductor properties: carrier concentration, conductivity, mobility, charge density, and charge sign.
    • It serves as a magnetic field meter and assesses carrier lifetime (τ), which varies for holes (τp) and electrons (τn).
    • Carrier lifetime signifies the average existence duration of charge carriers before recombination.

    Semiconductor Diode

    • A p-n junction forms when p-type and n-type semiconductors contact, creating a depletion region between them.
    • Free electrons from the n-type diffuse to the p-type, while holes migrate from p-type to n-type.
    • If reverse voltage exceeds the junction's peak-inverse voltage, damage occurs due to overheating.
    • The maximum forward current rating is vital to prevent junction destruction from excessive current.

    Rectifiers

    • Rectifiers convert alternating current (AC) to direct current (DC) and are classified into half-wave and full-wave rectifiers.

    Half-Wave Rectifier

    • Designed to rectify the positive half-cycle of an AC signal, using a transformer to step down voltage for safety.
    • The diode allows current to pass and convert it to pulsating DC across a load resistor.
    • Maximum rectifier efficiency is approximately 40.6%, defined in terms of load resistance (RL) and forward resistance (rf).

    Full-Wave Rectifier

    • Full-wave rectifiers are categorized into center-tapped and bridge rectifiers, allowing current flow during both halves of the AC cycle.
    • Efficiency is higher than half-wave due to better utilization of the input AC signal.

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    Description

    Test your understanding of n-type semiconductors with this quiz. Explore the key concepts and characteristics that distinguish n-type materials from others in the field of electronics. Ideal for students in physics or materials science classes.

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