Extrinsic Semiconductors - Definition, Types, FAQs

Semiconductor is a type of substance having electrical conductivity in between conductors and insulators . Some examples of semiconductors are silicon, germanium . In semiconductors electrons from the valence band get energy and jump to the conduction band, then the current starts flowing through the semiconductor. Semiconductors generally have 4 valence electrons in outermost shells. Addition of trivalent impurity to a semiconductor creates many p-type semiconductors and addition of pentavalent impurity to a semiconductor creates many n-type semiconductors.

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Types of semiconductor :

• Intrinsic semiconductor
• Extrinsic semiconductor

Though semiconductors are in two types: intrinsic semiconductor and extrinsic semiconductor. After learning what intrinsic and extrinsic semiconductors are. In this article we will learn about extrinsic semiconductor definition, examples of extrinsic semiconductor, doping semiconductor, doping definition . By mixing a special type of impurities conductivity of the semiconductor can be controlled.

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What do you mean by doping?

Doping is known as controlled mixing of impurities in semiconductors .The impurities are called dopants .

Doped meaning in tamil is ஊக்கமருந்து

What is Extrinsic Semiconductor ?

Extrinsic semiconductor is a special kind of semiconductor which drastically increases the conductivity of the semiconductor by mixing impurities in a controlled manner . When the conductivity of a semiconductor gets increased by doping, then the semiconductor is called extrinsic semiconductor .

Extrinsic meaning in a semiconductor is not the part of the substance, or a foreign particle in the semiconductor. If we define impurity, impurities meaning in a semiconductor is not the constituent particle of the semiconductor, it means other substances like arsenic, phosphorus etc .

Extrinsic semiconductor examples : Germanium (Ge) and silicon (Si) doped with arsenic (As) , phosphorus (P) etc.

Types of extrinsic semiconductor :

• n-type semiconductor
• p-type semiconductor

n-type semiconductor:

If pentavalent impurities or elements are dropped as impurities in the crystal of an intrinsic semiconductor in a controlled manner, the crystal thus formed is called an n-type semiconductor or n type extrinsic semiconductor.

Pentavalent impurities are called donors as they have five electrons in the outermost shell.

Also read :

• NCERT notes Class 12 Physics Chapter 14 Semiconductor Electronics: Materials, Devices and Simple Circuits
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Examples of n-type semiconductor: Arsenic (As) , phosphorus (P) acts as an n-type semiconductor in pure silicon (Si) or germanium (Ge) .

P -type semiconductor:

If trivalent impurities or elements are doped as impurities in a crystal in an intrinsic semiconductor in a controlled manner , the crystal thus formed is called a p-type semiconductor or p type extrinsic semiconductor.

Trivalent impurities examples/ Examples of p-type semiconductor : boron (Br) , aluminium (Al) doped in pure silicon (Si) or germanium (Ge) which works as a p-type semiconductor .

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