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

Engineering Funda

10 Aug 202312:23

Summary

TLDRThis 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.

Outlines

00:00

🔬 Introduction to Semiconductor Materials

The paragraph introduces the topic of semiconductor materials, contrasting them with conductors and insulators. It explains that semiconductors can be classified into intrinsic and extrinsic types. Intrinsic semiconductors are pure, without added impurities, and have lower conductivity compared to extrinsic semiconductors, which have impurities added to increase their conductivity. The concept of energy bands in materials is referenced, and the role of temperature in generating free charge carriers in intrinsic semiconductors is discussed. Silicon is given as an example of an intrinsic semiconductor material, with its four electrons in the outer orbit forming covalent bonds with neighboring atoms, resulting in no free charge carriers at 0 Kelvin. As temperature increases, electron-hole pairs are generated, which can increase conductivity. The negative temperature coefficient of intrinsic semiconductors is highlighted, meaning that as temperature rises, resistivity decreases due to the generation of more free charge carriers.

05:02

🌐 Extrinsic Semiconductor Materials and Conductivity

This paragraph delves into extrinsic semiconductor materials, which are created by adding impurities to pure semiconductors, resulting in higher conductivity. The unit of measurement for impurities, parts per million (PPM), is introduced. The paragraph explains the difference between n-type and p-type semiconductors. N-type materials have pentavalent impurities added, which contribute an extra electron, making them donor impurities and increasing the number of free electrons, thus enhancing conductivity. Examples of n-type impurities are phosphorus and arsenic. On the other hand, p-type materials have trivalent impurities added, which create vacancies or holes, making them acceptor impurities. Aluminum and boron are cited as examples of p-type impurities. The paragraph also discusses how the majority charge carriers in n-type materials are electrons, while in p-type materials, they are holes. The effect of temperature on the generation of electron-hole pairs is also mentioned, as well as the fact that the majority carriers in extrinsic semiconductors are determined by the type of impurity added.

10:02

🔩 Understanding P-Type Semiconductor Materials

The final paragraph focuses on p-type semiconductor materials, which are formed by adding trivalent impurities with three electrons in their outer orbit. This addition results in the creation of holes or vacancies in the electron structure, which are referred to as acceptor impurities because they can accept electrons. The paragraph explains that these holes are the majority charge carriers in p-type materials, while electrons are the minority carriers. The process of how covalent bonds can be broken, leading to the generation of electron-hole pairs, is discussed in three scenarios: increasing temperature, applying a higher potential difference, or applying a higher electric field. The paragraph concludes by summarizing the basics of semiconductor materials and inviting viewers to ask questions or share comments for further clarification.

Mindmap

Keywords

💡Semiconductor

A semiconductor is a material that lies between a conductor and an insulator in terms of its electrical conductivity. It can control the flow of electrical current. In the video, semiconductors are the central theme, with the speaker explaining how they are classified into intrinsic and extrinsic types, and how they function at different temperatures.

💡Intrinsic Semiconductor

An intrinsic semiconductor is a pure form of semiconductor material, such as silicon or germanium, that does not have any impurities added. It is characterized by having a lower conductivity compared to extrinsic semiconductors. In the video, the speaker explains that in intrinsic semiconductors, all electrons are involved in covalent bonds, resulting in no free charge carriers at 0 Kelvin, which is why their conductivity is initially low.

💡Extrinsic Semiconductor

Extrinsic semiconductors are materials where impurities are intentionally added to a pure semiconductor to modify its electrical properties. This addition of impurities increases the material's conductivity. The video discusses how extrinsic semiconductors are created by adding either n-type or p-type impurities to the base semiconductor material.

💡Covalent Bonds

Covalent bonds are a type of chemical bond formed by the sharing of electron pairs between atoms. In the context of the video, covalent bonds are crucial in intrinsic semiconductors, where all electrons are involved in such bonds, leaving no free charge carriers. The speaker illustrates how breaking these bonds, such as by increasing temperature, can generate free electrons and holes, thus increasing conductivity.

💡Electron-Hole Pair

An electron-hole pair refers to a free electron and the positively charged vacancy it leaves behind in a semiconductor material. When a covalent bond breaks, an electron can become free, creating a hole. The video explains that at 0 Kelvin, there are no free charge carriers, but as temperature increases, electron-hole pairs are generated, which is crucial for the conductivity of intrinsic semiconductors.

💡Negative Temperature Coefficient

The negative temperature coefficient refers to the property of a material where its resistivity decreases as the temperature increases. This is discussed in the video in relation to intrinsic semiconductors, where the generation of electron-hole pairs with rising temperature leads to an increase in free charge carriers, thus reducing resistivity.

💡N-Type Semiconductor

An n-type semiconductor is created by adding pentavalent impurities, such as phosphorus, to a semiconductor material. This results in an excess of free electrons, making electrons the majority charge carriers. The video explains that these impurities donate extra electrons, hence the term 'donor impurity,' and increase the material's conductivity.

💡P-Type Semiconductor

A p-type semiconductor is formed by adding trivalent impurities, such as aluminum or boron, to a semiconductor material. This creates an excess of holes, making holes the majority charge carriers. The video describes these impurities as 'acceptor impurities' because they accept electrons, leading to an increase in the material's conductivity.

💡Impurities

Impurities in the context of semiconductors refer to the deliberate addition of atoms that have a different number of valence electrons than the base semiconductor material. The video explains that impurities define the number of free electrons and holes in extrinsic semiconductors, which in turn determines the material's conductivity. The speaker distinguishes between pentavalent (n-type) and trivalent (p-type) impurities and their effects on semiconductor properties.

💡Conductivity

Conductivity in semiconductors is the measure of a material's ability to conduct electric current. The video discusses how conductivity in intrinsic semiconductors is initially low due to the absence of free charge carriers but increases with temperature as electron-hole pairs are generated. In extrinsic semiconductors, conductivity is higher due to the presence of impurities that introduce free charge carriers.

Highlights

Introduction to semiconductor materials and their classification into intrinsic and extrinsic types.

Explanation of intrinsic semiconductors as pure materials with no impurities added.

Description of silicon as a prime example of an intrinsic semiconductor material.

Discussion on the lower conductivity of intrinsic semiconductors compared to extrinsic ones.

Explanation of how electron-hole pairs are generated in intrinsic semiconductors at increased temperatures.

The concept of negative temperature coefficient in intrinsic semiconductors.

Examples of intrinsic semiconductor materials, such as silicon and germanium.

Introduction to extrinsic semiconductors and their higher conductivity due to impurities.

Definition and role of impurities in defining the number of free electrons and holes in extrinsic semiconductors.

Explanation of n-type semiconductors with the addition of pentavalent impurities.

Details on how phosphorus impurities contribute to the creation of free electrons in n-type materials.

Introduction to p-type semiconductors with the addition of trivalent impurities.

Role of aluminum impurities in creating free holes in p-type semiconductor materials.

Discussion on donor and acceptor impurities in n-type and p-type semiconductors, respectively.

Explanation of majority and minority charge carriers in n-type and p-type semiconductors.

Mechanisms for breaking covalent bonds in semiconductors through temperature, potential difference, and electric field.

Summary of the basics of semiconductor materials and their practical applications.