Extrinsic Semiconductors - Definition, Types, FAQs

A semiconductor is a type of substance having electrical conductivity between conductors and insulators. 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 their outermost shells. The addition of a trivalent impurity to a semiconductor creates many p-type semiconductors and the addition of a pentavalent impurity to a semiconductor creates many n-type semiconductors. In this article, we will discuss types of semiconductors, what is extrinsic semiconductor, extrinsic semiconductor examples, n-type semiconductor diagrams, p-type semiconductor diagrams, factors affecting extrinsic semiconductors, difference between n-type and p-type semiconductors, and application of extrinsic semiconductor

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This Story also Contains

1. What is Extrinsic Semiconductor?
2. Types of Extrinsic Semiconductors
3. N-type Semiconductor
4. P-type Semiconductor
5. Factors Affecting Extrinsic Semiconductors
6. Applications of Extrinsic Semiconductor
7. Energy Band Diagram For P-type and N-type Semiconductor
8. Difference Between P-type and N-type Semiconductors

Types of Semiconductors

• Intrinsic semiconductor
• Extrinsic semiconductor

Semiconductors are of two types: intrinsic semiconductors and extrinsic semiconductors.

What do you mean by doping?

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

What is Extrinsic Semiconductor?

Extrinsic semiconductor definition: Extrinsic semiconductor is a special kind of semiconductor that drastically increases the electric 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 an extrinsic 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 Semiconductors

Extrinsic semiconductors are classified into two types depending on the doping and the majority charge carriers.

• 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.

Examples of n-type semiconductors

Arsenic (As), and phosphorus (P) act 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 semiconductors

Boron (Br), aluminum (Al) doped in pure silicon (Si), or germanium (Ge) which works as a p-type semiconductor.

Factors Affecting Extrinsic Semiconductors

1. Doping Element type
2. Amount of impurities added
3. Temperature
4. Energy band gap
5. Mobility of charge carriers
6. Type of semiconductor material

Applications of Extrinsic Semiconductor

1. Diodes (P-N junction diode, Zener diode, LED)
2. Transistors
3. Photodiodes
4. Solar cells
5. Lasers
6. Phototransistors
7. Rectifiers
8. Light detectors

Energy Band Diagram For P-type and N-type Semiconductor

P-type Semiconductor Diagram

N-type Semiconductor Diagram

Difference Between P-type and N-type Semiconductors

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