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Electronic Component

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You’ve probably heard of Silicon Valley. You may even know that it’s a region in northern California. But do you know how the region got its name? Silicon Valley is the birthplace of modern electronics and continues to be a hub of electronic innovation. The word silicon in the name refers to the element silicon, which is the chief “ingredient” of electronic components.

What Are Electronic Components?

Electronic components are the parts used in electronic devices such as computers. The components change electric current so it can carry information. Types of electronic components include diodes, transistors, and integrated circuits, all of which you can read about below. However, to understand how these components work, you first need to know about semiconductors. That’s because electronic components consist of semiconductors—sometimes millions of them!

Semiconductors

A semiconductor is a solid crystal, consisting mainly of silicon. It gets its name from the fact that it can conduct current better than an electric insulator but not as well as an electric conductor. As you can see in the Figure below , each silicon atom has four valence electrons that it shares with other silicon atoms in the crystal. A semiconductor is formed by replacing a few silicon atoms with other atoms, such as phosphorus or boron, which have more or less valence electrons than silicon. This is called doping, and it’s what allows the semiconductor to conduct electric current.

Semiconductors are created by "doping" silicon

Q: Why wouldn’t a pure silicon crystal be able to conduct electric current?

A: Electric current is a flow of electrons. All of the valence electrons of silicon atoms in a pure crystal are shared with other silicon atoms, so they are not free to move and carry current.

There are two different types of semiconductors: n-type and p-type.

  • An n-type (negative-type) semiconductor consists of silicon and an element such as phosphorus that gives the silicon crystal extra electrons. You can see this in the Figure above . An n-type semiconductor is like the negative terminal of a battery.
  • A p-type (positive-type) semiconductor consists of silicon and an element such as boron that gives the silicon positively charged “holes” where electrons are missing. This is also shown in the Figure above . A p-type semiconductor is like the positive terminal of a battery.

Diode

A diode is an electronic component that consists of a p-type and an n-type semiconductor placed side by side, as shown in the Figure below . When a diode is connected by leads to a source of voltage, electrons flow from the n-type to the p-type semiconductor. This is the only direction that electrons can flow in a diode. This makes a diode useful for changing alternating current to direct current.

Diagram of a diode

Transistor

A transistor consists of three semiconductors, either p-n-p or n-p-n. Both arrangements are illustrated in the Figure below . Current can’t flow through a transistor unless a small amount of current is applied to the center semiconductor (through the base). Then a much larger current can flow through the transistor from end to end (from collector to emitter). This means that a transmitter can be used as a switch, with pulses of a small current turning a larger current on and off. A transistor can also be used to increase the amount of current flowing through a circuit. You can learn more about transistors and how they work at this URL: http://www.youtube.com/watch?v=ZaBLiciesOU

Diagram of a transistor

Integrated Circuit

An integrated circuit—also called a microchip—is a tiny, flat piece of silicon that consists of layers of many electronic components such as transistors. You can see an integrated circuit in the Figure below . Look how small it is compared with the finger it’s resting on. Although the integrated circuit is tiny, it may contain millions of smaller electronic components. Current flows extremely rapidly in an integrated circuit because it doesn’t have far to travel. Integrated circuits are used in virtually all modern electronic devices to carry out specific tasks. You can see how integrated circuits are made at this URL: http://www.youtube.com/watch?v=RHAso1yM-D4 .

Microchips are very small

Summary

  • Electronic components are the parts used in electronic devices such as computers. Types of electronic components include diodes, transistors, and integrated circuits.
  • Electronic components consist of semiconductors, which are solid crystals consisting mainly of silicon. There are two types of semiconductors, called n-type and p-type.
  • A diode is an electronic component consisting of two semiconductors. It is used to change alternating current to direct current.
  • A transistor is an electronic component consisting of three semiconductors. It can be used to turn current on or off or to increase current.
  • An integrated circuit (microchip) is an electronic component that consists of many other electronic components such as transistors. Integrated circuits are used in virtually all modern electronic devices to carry out specific tasks.

Vocabulary

  • semiconductor : Solid crystal—usually consisting mainly of silicon—that can conduct current better than an electric insulator but not as well as an electric conductor; found in electronic components.

Practice

Explore the semiconductor animation at the following URL, and then answer the questions below. http://www.ustudy.in/node/3503

  1. How can you make the semiconductor a p-type semiconductor? How do the positive “holes” flow in this type of semiconductor?
  2. What do you have to do to change the semiconductor to an n-type semiconductor? How do the electrons flow in this type of semiconductor?

Review

  1. What are electronic components?
  2. Compare and contrast n-type and p-type semiconductors.
  3. Describe the structure and function of a diode.
  4. How does a transistor act as a switch?
  5. Explain how the size of an integrated circuit helps it carry out tasks with incredible speed.

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