Semiconductor Devices

What is a Semiconductor Device?

Semiconductor devices are electronic circuits that are neither good conductors nor good insulators. These devices are preferred due to low cost, reliability and compactness. In the last 70 years, these devices have become extremely popular in the manufacture of various electronic devices.

Most metals are good conductors, meaning that they allow electricity to flow freely. This includes copper and aluminium, both of which are widely used in electronics.

Similarly, materials such as glass, wood and plastic are insulators, which prevent the flow of electricity. 

Semiconductor devices come with a fusion of properties of both conductors and insulators. At room temperature, these devices possess lower electrical conductivity than conductors. 

Nevertheless, at such a state, the lists of semiconductor devices offer high conductivity when compared to insulators.

 

Holes and Electrons in Semiconductor Devices

In semiconductors, electrons and holes carry an electronic charge. Holes carry the positively charged particles, while electrons carry negatively charged particles within a semiconductor. The magnitude is equal for holes and electrons. However, their polarity is opposite to that of each other.

 

Semiconductor Properties

As stated previously, semiconductor devices can conduct electricity under ideal circumstances or conditions. Nevertheless, listed below are some other properties of a semiconductor – 

  • Conductivity of a semiconductor increases with rise in temperature, i.e. application of heat.

  • Flow of current due to holes and electrons

  • Reduction of power losses

  • Semiconductor devices can conserve energy by doping

  • Resistance decreases with increase in temperature  

 

Materials Exhibiting Semiconductor Properties

The following are examples of semiconductor elements and compounds – 

  • Selenium

  • Germanium

  • Silicon

  • Tellurium

  • Gallium arsenide

 

Types of Semiconductor Devices

Semiconductors can be broadly categorised into two types – three-terminal devices and two-terminal devices. The distinction is based on the physics of semiconductor devices.

 

  1. Two-terminal Semiconductors – These are semiconductor materials, which come with only one positive-negative (p-n) junction.

 

  1. Three-terminal Semiconductors – These semiconductor materials possess a positive-negative-positive (p-n-p) junction.

 

Refer to the table below to learn about the various examples of semiconductors –

Examples of Semiconductor Devices

Examples of Two-terminal Semiconductor

Examples of Three-terminal Semiconductor

DIAC

TRIAC

PIN Diode

Field Effect Transistor

Tunnel Diode

Darlington Transistor

Laser Diode

Thyristor

Schottky Diode

Silicon Controlled Rectifier (SCR)

Zener Diode

Unijunction Transistor

 

What are Transistors?

Transistors are three-terminal semiconductors. Transistors are divided into two types, namely, field effect transistor and bipolar junction transistor. The latter is formed by two p-n junctions to form p-n-p and n-p-n configurations. Such a transistor houses three parts – middle, emitter and collector.

Field effect transistors, on the other hand, rely on electric fields to alter the principles of conductivity.    

 

What are Diodes?

Diodes are an example of a two-terminal semiconductor, with one p-n junction. Such diodes are formed by interlinking p-type and n-type semiconductor materials. It is an effective device, because the p-region houses a substantial concentration of holes, while n-region includes a high quantity of electrons.

 

Multiple Choice Questions

Which of These is an Example of Conductors?

  1. Wood

  2. Copper

  3. Glass

  4. Plastic

Ans. (b) Copper

 

Applications of Semiconductor Devices

Semiconductor devices are widely used across several electronic fields. Some of its applications are listed below – 

  • Can be safely used in electrical appliances which require high voltage.

  • Transistors are indispensable parts for integrated circuits, including microprocessors.

  • Semiconductor devices are essential to building logic gates and other forms of digital circuits.

  • Such materials are extremely useful when designing amplifiers and oscillators.

We, at Vedantu, can help you understand the functionalities and applications of semiconductor devices better. Our expert teachers can also help students evaluate their Physics preparation. 

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FAQ (Frequently Asked Questions)

1. How Does Increase in Temperature Affect Electrical Conductivity for a Semiconductor Device?

Applying heat to a semiconductor leads to an increase in current flow through a semiconductor material. Thus, for semiconductors, temperature is directly proportional to conductivity.

2. What are the Two Types of Semiconductor Devices?

One can divide semiconductor devices into two-terminal and three-terminal semiconductors. A diode is an example of a two-terminal semiconductor, while transistors are three-terminal variants.

3. What is a Common Application of Semiconductor Materials?

Semiconductor materials are commonly used to create microprocessors. Additionally, these materials are also suitable for high-voltage appliances.