Types of Semiconductor Materials | Intrinsic & Extrinsic Semiconductor | Engineering Funda

Summary

This engineering video delves into semiconductor materials, distinguishing between intrinsic and extrinsic types. Intrinsic semiconductors, like pure silicon, have low conductivity due to a lack of free charge carriers, but their conductivity increases with temperature as electron-hole pairs are generated. Extrinsic semiconductors, in contrast, have higher conductivity due to added impurities. N-type materials are doped with pentavalent impurities, introducing extra electrons, while P-type materials incorporate trivalent impurities, creating holes. The video explains how these impurities define the number of free electrons and holes, affecting the material's conductivity and temperature coefficient.

Takeaways

• 😀 Semiconductor materials are categorized into intrinsic and extrinsic types, with the former being pure and the latter having added impurities.
• 🔍 Intrinsic semiconductors, such as pure silicon, have lower conductivity due to the absence of free charge carriers, as all electrons are involved in covalent bonds.
• 🌡️ The conductivity of intrinsic semiconductors increases with temperature because thermal energy can break covalent bonds, generating electron-hole pairs.
• ⬇️ Intrinsic semiconductors exhibit a negative temperature coefficient, meaning their resistivity decreases as temperature increases due to the generation of more free charge carriers.
• 🔋 Examples of intrinsic semiconductor materials include silicon and germanium, which are widely used in electronic devices like chips.
• 📈 Extrinsic semiconductors have higher conductivity than intrinsic ones because impurities introduce additional free charge carriers.
• 🔬 N-type semiconductors are created by adding pentavalent impurities like phosphorus, which donate free electrons, increasing conductivity.
• 🔧 P-type semiconductors are formed by introducing trivalent impurities like aluminum, which create vacancies or holes that act as free charge carriers.
• 🏭 Both n-type and p-type semiconductors are used in various electronic applications, with n-type materials having electrons as majority carriers and p-type having holes as majority carriers.
• ⚙️ Covalent bonds in semiconductors can be broken not only by increasing temperature but also by applying a high potential difference or a strong electric field, leading to the generation of electron-hole pairs.

Q & A

What are the three categories of solid materials mentioned in the script?

The three categories of solid materials mentioned are conductors, semiconductors, and insulators.

What is an intrinsic semiconductor material?

An intrinsic semiconductor material is a pure semiconductor material with no impurities added, such as pure silicon or germanium.

How does the conductivity of intrinsic semiconductor materials compare to extrinsic semiconductor materials?

Intrinsic semiconductor materials have lower conductivity compared to extrinsic semiconductor materials because they do not have additional free charge carriers.

What happens to the conductivity of intrinsic semiconductors when the temperature increases?

As the temperature increases, electron-hole pairs are generated, which increases the number of free charge carriers and thus increases the conductivity.

What is the term for the phenomenon where resistivity decreases with an increase in temperature in intrinsic semiconductors?

The phenomenon where resistivity decreases with an increase in temperature is called a negative temperature coefficient.

What are the two basic types of extrinsic semiconductor materials?

The two basic types of extrinsic semiconductor materials are n-type and p-type.

Which impurities are added to create n-type semiconductor material, and why?

Pentavalent impurities, such as phosphorus or arsenic, are added to create n-type semiconductor material because they have five electrons in their outer orbit, which results in an extra free electron and thus increases conductivity.

How do trivalent impurities contribute to the formation of p-type semiconductor material?

Trivalent impurities, such as aluminum or boron, contribute to the formation of p-type semiconductor material by creating vacancies or holes in the electron structure, which increases the number of free holes and conductivity.

What is the term for impurities that add free electrons in n-type semiconductors?

The term for impurities that add free electrons in n-type semiconductors is 'donor impurities' because they donate an extra electron.

What is the term for impurities that add free holes in p-type semiconductors?

The term for impurities that add free holes in p-type semiconductors is 'acceptor impurities' because they accept an electron, creating a hole.

What are the three ways mentioned in the script to generate electron-hole pairs in semiconductor materials?

The three ways to generate electron-hole pairs in semiconductor materials are by increasing temperature, applying a higher potential difference across the material, or applying a higher electric field through the material.