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Semiconductor: What is Intrinsic and Extrinsic Semiconductor ? P-Type and n-Type Semiconductor
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Semiconductor: What is Intrinsic and Extrinsic Semiconductor ? P-Type and n-Type Semiconductor

Introduction to Semiconductor Materials

Overview of Semiconductors

  • The video introduces semiconductor materials, which are essential for manufacturing electronic devices such as transistors, diodes, and integrated circuits.
  • Understanding semiconductor physics and materials is crucial for grasping the basics of semiconductor devices.

Classification of Materials by Conductivity

  • Materials are classified into three categories based on conductivity: conductors, insulators, and semiconductors.
  • Conductors (e.g., silver, copper) have high conductivity (around 10^7 Siemens/m), allowing easy charge flow.
  • Insulators (e.g., wood, glass) exhibit very low conductivity (around 10^-14 Siemens/m), restricting charge flow.

Understanding Semiconductor Behavior

Properties of Semiconductors

  • Semiconductors have moderate conductivity between conductors and insulators; their conductivity can be altered by adding impurities.
  • Silicon is highlighted as a key example in the electronics industry due to its atomic structure with 14 protons and electrons.

Atomic Structure of Silicon

  • Silicon has four valence electrons that form covalent bonds in a crystal structure through electron sharing among neighboring atoms.

Electron Movement in Silicon

Thermal Energy Effects

  • At temperatures above absolute zero, thermal energy causes silicon atoms to vibrate, potentially breaking covalent bonds and creating free electrons.

Creation of Holes

  • When an electron breaks free from its bond, it leaves behind a vacancy known as a "hole," which carries a positive charge.

Current Flow in Semiconductors

Generation and Recombination

  • At room temperature, there is continuous generation and recombination of holes and electrons within silicon structures.
  • Current flows in semiconductors due to both free electrons and holes—unlike conductors where current flows only through electrons.

Types of Semiconductors

Intrinsic vs. Extrinsic Semiconductors

  • Intrinsic semiconductors are pure materials without impurities; all atoms are identical (e.g., pure silicon).

Understanding Semiconductor Behavior

Conductivity Control in Semiconductors

  • The conductivity of semiconductors can be altered to control their behavior, making them essential in the electronics industry.
  • Extrinsic semiconductors are classified into p-type and n-type based on the type of impurity or dopant added.

P-Type Semiconductors

  • P-type semiconductors are created by adding trivalent atoms (e.g., aluminum, boron, gallium) to silicon, which have three electrons in their outermost orbit.
  • Each trivalent atom creates one hole due to a vacancy left after sharing three electrons with neighboring atoms.
  • These trivalent atoms are referred to as acceptor atoms because they can accept external free electrons.

N-Type Semiconductors

  • N-type semiconductors result from adding pentavalent impurities (e.g., arsenic, antimony, phosphorus), which have five electrons in their outermost orbit.
  • In this case, four out of five electrons are shared with neighboring silicon atoms, leaving one free electron that roams within the crystal structure.

Charge Carriers in Semiconductors

  • In p-type semiconductors, holes act as majority carriers while electrons are minority carriers; conversely, n-type semiconductors have excess electrons as majority carriers and holes as minority carriers.
  • When voltage is applied to a p-type semiconductor, current primarily flows due to holes moving towards the negative terminal; for n-type semiconductors, current flows mainly due to electrons moving towards the positive terminal.

Current Flow Dynamics

  • The flow of current in p-type and n-type semiconductors is dictated by the movement of charge carriers: holes for p-types and electrons for n-types.
Playlists: Analog Electronics
Video description

In this video, the semiconductor basics have been explained. By watching this video you will learn the following topics: 0:54 Types of material: Conductor, Insulator and Semiconductor 2:29 Basics of Semiconductor and the concept of holes and electrons in the semiconductor 6:06 Intrinsic and Extrinsic Semiconductor 7:00 p-type and n-type semiconductor The semiconductor materials like Silicon, Germanium, and GaAs are widely used in the electronics industry for making electronic devices like a diode, transistor, and other integrated circuits. In terms of the conductivity, the conductivity of the semiconductor materials is in between the conductor and insulator. Conductors like Copper, Silver has very good conductivity. While insulators like Dry wood, rubber, mica have very poor conductivity. But the conductivity of the semiconductor is in between the conductor and insulator. Moreover that in semiconductor, by adding the external impurities, the conductivity can be changed. And this property is mainly used in manufacturing various electronic devices. Unlike conductor, in semiconductor, there are two types of charges which contribute in the flow of current. 1) Electrons 2) Holes And by adding the external impurities the concentration of electrons and holes can be controlled. The semiconductors can be classified into two categories 1) Intrinsic Semiconductor 2) Extrinsic Semiconductor In the intrinsic semiconductor, no external impurities are added. And the concentration of holes and electrons is equal at the given temperature. In the extrinsic semiconductor, the external impurities are added. And further depending on the type of external impurity, the extrinsic semiconductor can be classified as 1) p-type semiconductor 2) n-type semiconductor p-type semiconductor: In the p-type semiconductor, the trivalent impurities like Boron, Aluminum, and Gallium are added to generate the excessive holes. n-type semiconductor: In the n-type semiconductor, the pentavalent atoms like arsenic, antimony and phosphorous are added to generated the excessive electrons. This video will be helpful to all the students of science and engineering in understanding the basics of the semiconductor. #Semiconductor #ptypeSemiconductor #ntypeSemiconductor Follow me on YouTube: https://www.youtube.com/allaboutelectronics Follow me on Facebook: https://www.facebook.com/ALLABOUTELECRONICS/ Follow me on Instagram: https://www.instagram.com/all_about.electronics/ Music Credit: http://www.bensound.com/