Semiconductors – Types, Examples, Properties, Applications

Semiconductors are materials that have an electrical conductivity value falling between that of conductors, such as copper, and insulators, such as glass. Generally, their resistivity decreases as the temperature rises, which is opposite to the behavior of metals.

In electronics and modern technology, semiconductor holds a pivotal role. These materials are the backbone of devices influencing our daily lives, from smartphones to solar panels. This article will explore the concept of semiconductors, their types, properties, examples, and applications, offering a comprehensive look at these crucial components.

What is a Semiconductor?

A semiconductor is a substance with electrical conductivity between a conductor (like copper) and an insulator (like glass). Its ability to conduct electricity falls somewhere between these two extremes. The unique aspect of semiconductor is a variable conductivity, which can be altered and controlled by adding impurities—a process known as doping—or by applying electrical fields or light.

Structure and Band Theory

At a molecular level, a semiconductor is typically crystalline in form. Their electrical behavior is defined through band theory, which describes two energy bands: the valence band (fully occupied by electrons) and the conduction band (where electrons can move freely). The energy gap between these bands, known as the bandgap, is crucial as it determines the semiconductor’s electrical conductivity.

Types of Semiconductors


Semiconductors can be broadly classified into two types based on their bandgap:

  1. Intrinsic Semiconductors: These are pure forms of semiconductors without any significant amounts of impurities. Silicon and germanium are classic examples, which are used in their purest form.
  2. Extrinsic Semiconductors: These are chemically doped semiconductors designed to enhance their conductivity. Doping involves adding a small amount of impurity atoms to an intrinsic semiconductor to alter its electrical properties.
    • N-type Semiconductors: These are created by doping an intrinsic semiconductor with atoms that have more valence electrons than the semiconductor. For example, doping silicon with phosphorus adds extra electrons, creating more free carriers (electrons).
    • P-type Semiconductors: Contrary to N-type, P-type semiconductors are made by doping materials with fewer valence electrons. This creates “holes” (positive charge carriers), as seen when silicon is doped with boron.

Properties of Semiconductors

The following are the key properties.

  • Variable Conductivity: Unlike metals, the conductivity of semiconductors increases with temperature, as more carriers are available to conduct electricity.
  • Response to Doping: Doping significantly changes the electrical properties, allowing for the control of electrical behavior in semiconductor devices.
  • Photoconductivity: The conductivity of the semiconductor increases when exposed to light, a property utilized in photodetectors and solar cells.

Examples of Semiconductors:

  • Silicon(Si)
  • Germanium(Ge)
  • Gallium Arsenide(GaAs)
  • Indium Phosphide (InP)
  • Silicon Carbide (SiC)
  • Gallium Nitride (GaN)
  • Cadmium Telluride (CdTe)
  • Lead Sulfide (PbS)


Semiconductors are integral to numerous applications across various sectors:

  • Microelectronics: Silicon chips are the heart of all electronic devices, from computers to mobile phones.
  • Optoelectronics: Materials like gallium arsenide are used in LEDs and laser diodes.
  • Power Devices: Silicon carbide and gallium nitride are used in high-power applications like electric vehicles and grid storage.
  • Solar Cells: Polycrystalline silicon is commonly used in photovoltaic cells that convert solar energy into electrical energy.


In conclusion, semiconductors are crucial for modern technology due to their unique electrical properties. These materials, including types like silicon and gallium arsenide, are used in everything from basic diodes to complex microprocessors. They offer great potential for advancements in computing, telecommunications, and renewable energy.

  1. P-type Semiconductor
  2. N-type semiconductor
  3. Intrinsic semiconductor
  4. Extrinsic Semiconductor

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