Tag: intrinsic and extrinsic semiconductors

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Questions Related to intrinsic and extrinsic semiconductors

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

The number density of electrons is not equal to the number density of holes

  1. Extrinsic semiconductors

  2. Intrinsic semiconductors

  3. both of them

  4. none of them
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In an extrinsic semiconductor, doped with an impurity. For example, an n-type semiconductor which is formed by doping n-type impurity so that number of electrons are more than the number of holes. So, the number density of holes is not equal to the number density of electrons. Because in an extrinsic semiconductor, one of the two carriers are in abundance and the other one is in majority.

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

The number density of electrons is equal to the number density of holes in

  1. Intrinsic semiconductors

  2. Extrinsic semiconductors

  3. both of them

  4. none of them
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In an intinsic semiconductor number density of electrons and holes are always equal. As the number of electrons generated in the conduction band is equal to the number of holes generated in the valance band.

At absolute zero temperature valance band is completely filled and conduction band is completely empty.

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

The crystals of pure elements like germanium and silicon are considered as:

  1. Intrinsic Semiconductor.

  2. Extrinsic semiconductors

  3. both of them

  4. none of them
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A pure semiconductor is called an intrinsic semiconductor. It has thermally generated current carriers. Germanium and silicon are frequently used as semiconductors. The intrinsic semiconductor has no impurity added to them.

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

Which conductor has more electrical conductivity?

  1. Intrinsic semiconductors

  2. Extrinsic semiconductors

  3. Both have same.

  4. Can't compare
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The conductivity of an extrinsic semiconductor is more than that of an intrinsic semiconductor. This is because, in an intrinsic (pure) semiconductor, the carriers are only thermally generated carriers. But in extrinsic semiconductors, which is doped with a p-type or n-type impurity to form p-type and n-type semiconductor so as to increase the number of holes or number of electrons in a semiconductor respectively. More the charge carriers, more is the conductivity.

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

Semiconductors those are created by doping an intrinsic semiconductor with donor impurities are

  1. p-type

  2. n-type

  3. may be any of them

  4. none of them
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Donor impurities are the ones that donate electrons to the semiconductor atom. For each donor atom added, there is one electron donated to the semiconductor atom. As a result, the electrons in such type of semiconductors are majority charge carriers. Therefore, this extrinsic semiconductor formed by adding donor impurities are called n-type semiconductors.

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

Transistors (devices that enable current switching) make use of

  1. Intrinsic semiconductor

  2. Extrinsic semiconductor

  3. both of them

  4. none of them
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A transistor is a device which consists of a thin layer of one type of extrinsic semiconductor sandwiched between two thick layers of other types of extrinsic semiconductor. There are two types of transistors:

  1. pnp transistor and,
  2. npn transistor
    So, a transistor is made of extrinsic semiconductor.

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

 A semiconductor diode (devices that allow current in only one direction) consists of 

  1. Intrinsic semiconductor

  2. Extrinsic semiconductor

  3. both of them

  4. none of them
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A semiconductor diode consists of p-n junction having metallic contacts at both the ends. A single piece of a semiconductor material (either Si or Ge) with one portion doped with a pentavalent impurity and other portion doped with trivalent impurity behaves as a p-n junction. Means, extrinsic semiconductor or semiconductor doped with impurities of both p and n are used in p-n junction diode.

Multiple choice intrinsic and extrinsic semiconductors types of semiconductors electronic devices semiconductor electronics: materials, devices and simple circuits physics

The impurity atoms with which pure silicon should be doped to make a p - type semiconductor are those of :

  1. phosphorus

  2. antimony

  3. boron

  4. aluminium
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Explanation

p type semiconductor has more number of holes than electrons.
P-type semiconductors are created by doping an intrinsic semiconductor with acceptor impurities like boron, aluminium and other group IIIA elements