Team Physics -
Created by: Team Physics -, Last Updated: July 5, 2024


Semiconductors are materials that have electrical conductivity between conductors (like metals) and insulators (like ceramics). They are essential in modern electronics, enabling the function of devices such as diodes, transistors, and integrated circuits. Made from elements like silicon, germanium, gallium, and hafnium, semiconductors can be modified through doping, where impurities are added to change their electrical properties. This ability to control conductivity makes semiconductors fundamental to the operation of computers, smartphones, and solar cells. Their unique properties facilitate the development of miniature, high-performance electronic components, driving advancements in technology and industry.

What Are Semiconductors?

Semiconductors are materials with electrical conductivity between that of conductors and insulators, essential for modern electronics like computers and smartphones. Primarily made from silicon, their properties can be modified through doping to control electrical behavior. This enables their use in components such as diodes, transistors, and integrated circuits, crucial for switching and amplifying electrical signals.

Examples of Semiconductors

  1. Silicon (Si)
    • The most widely used semiconductor in the electronics industry, forming the basis of most integrated circuits and transistors.
  2. Germanium (Ge)
    • Used in high-speed electronic devices and fiber-optic systems due to its excellent electron mobility.
  3. Gallium Arsenide (GaAs)
    • Known for its high electron mobility and direct bandgap, making it ideal for high-frequency and optoelectronic applications.
  4. Indium Phosphide (InP)
    • Used in high-power and high-frequency electronics, as well as in photonic devices like lasers and LEDs.
  5. Silicon Carbide (SiC)
    • Known for its high thermal conductivity and electric field breakdown strength, making it suitable for high-temperature and high-power applications.
  6. Gallium Nitride (GaN)
    • Offers high efficiency and power density, commonly used in LEDs, high-frequency, and high-power devices.
  7. Cadmium Telluride (CdTe)
    • Often used in thin-film solar cells due to its optimal bandgap for converting sunlight into electricity.
  8. Zinc Oxide (ZnO)
    • Utilized in transparent electronics, UV light emitters, and piezoelectric devices due to its wide bandgap and high exciton binding energy.
  9. Copper Indium Gallium Selenide (CIGS)
    • Used in high-efficiency thin-film solar cells, known for its flexible applications and high absorption coefficient.
  10. Lead Sulfide (PbS)
    • Employed in infrared detectors and sensors due to its narrow bandgap and sensitivity to infrared light.

Semiconductors Examples in Real Life

  1. Computers and Laptops: The central processing units (CPUs) and memory chips in computers are made from semiconductors, allowing for the rapid processing of data.
  2. Smartphones: Semiconductors are used in the microprocessors, memory, and various sensors, making smartphones powerful and multifunctional devices.
  3. Solar Panels: Photovoltaic cells in solar panels are made from semiconductor materials like silicon, converting sunlight into electrical energy.
  4. LEDs: Light-emitting diodes (LEDs) use semiconductors to produce light efficiently, used in displays, lighting, and indicators.
  5. Televisions and Monitors: Modern LED and OLED screens rely on semiconductors for high-resolution displays and energy efficiency.
  6. Automobiles: Semiconductors are critical in automotive electronics, including engine control units, infotainment systems, and advanced driver-assistance systems (ADAS).
  7. Medical Devices: Diagnostic equipment like MRI and CT scanners, as well as wearable health monitors, use semiconductors for precise and reliable operation.
  8. Household Appliances: Devices such as washing machines, refrigerators, and microwaves use semiconductors for control systems and energy management.
  9. Gaming Consoles: Semiconductors are used in the processors and graphics units, providing the computational power needed for advanced gaming experiences.
  10. Smart Home Devices: Products like smart thermostats, security cameras, and voice-activated assistants rely on semiconductor technology for connectivity and functionality.

Types of Semiconductors

Types of Semiconductors

1. Intrinsic Semiconductor

An intrinsic semiconductor is a pure form of semiconductor material, such as silicon or germanium, without any significant impurities added. The electrical conductivity of intrinsic semiconductors is solely dependent on the properties of the material itself and temperature. At absolute zero temperature, an intrinsic semiconductor behaves like an insulator. As the temperature increases, thermal energy excites electrons from the valence band to the conduction band, creating electron-hole pairs that contribute to electrical conduction. Intrinsic semiconductors are foundational in understanding the behavior of more complex, doped semiconductors used in various electronic devices.

2. Extrinsic Semiconductor

An extrinsic semiconductor is a type of semiconductor that has been intentionally doped with impurities to modify its electrical properties. There are two main types of extrinsic semiconductors:

  1. N-Type Semiconductor: This is created by doping the semiconductor material with donor impurities that have more valence electrons than the host material (e.g., doping silicon with phosphorus). The additional electrons from the donor atoms provide free electrons for conduction, increasing the material’s conductivity.
  2. P-Type Semiconductor: This is formed by doping the semiconductor with acceptor impurities that have fewer valence electrons than the host material (e.g., doping silicon with boron). The lack of electrons creates “holes,” or positive charge carriers, which facilitate electrical conduction.

Extrinsic semiconductors are crucial in the fabrication of electronic components such as diodes, transistors, and integrated circuits, as the doping process allows precise control over their electrical characteristics.

Difference between Intrinsic and Extrinsic Semiconductors

FeatureIntrinsic SemiconductorsExtrinsic Semiconductors
DefinitionPure semiconductor materials with no intentional impurities added.Semiconductor materials doped with impurities to modify electrical properties.
ConductivityRelatively low, dependent on temperature and material properties.Significantly higher, dependent on type and concentration of dopant impurities.
Charge CarriersEqual numbers of electrons and holes created by thermal excitation.Majority carriers determined by doping: n-type has more electrons, p-type has more holes.
DopingNo doping; pure elements like silicon or germanium.Doped with donor (n-type) or acceptor (p-type) atoms to increase free charge carriers.
ExamplesPure silicon (Si), pure germanium (Ge).Silicon doped with phosphorus (n-type), silicon doped with boron (p-type).
ApplicationsUsed in research and study of semiconductor properties.Used in diodes, transistors, and integrated circuits for enhanced electrical properties.
Temperature DependenceConductivity increases significantly with temperature.Less dependent on temperature changes, stable number of charge carriers due to doping.

Applications of Semiconductors

  1. Electric Vehicles (EVs): Semiconductors are used in the power electronics, battery management systems, and motor drives of electric vehicles, enhancing their performance and efficiency.
  2. Wearable Technology: Devices such as fitness trackers, smartwatches, and health monitors rely on semiconductors for processing data and connectivity.
  3. Data Centers: Semiconductors are critical in servers, storage devices, and networking equipment, supporting the infrastructure of cloud computing and big data analytics.
  4. Digital Cameras: Image sensors in digital cameras use semiconductor technology to capture high-resolution images and videos.
  5. Robotics: Semiconductors enable the control systems and sensors in robots, allowing for precise movements and automation in various industries.
  6. Internet of Things (IoT): IoT devices, including smart home appliances, industrial sensors, and environmental monitors, rely on semiconductors for connectivity and data processing.
  7. 3D Printing: Semiconductors are used in the control systems and sensors of 3D printers, facilitating precise and efficient additive manufacturing.
  8. Virtual Reality (VR) and Augmented Reality (AR): VR and AR devices use semiconductors in their displays, sensors, and processing units to create immersive experiences.
  9. Banking and Financial Services: Semiconductors are used in secure banking systems, including ATMs, credit card readers, and online transaction processing.
  10. Aerospace Navigation Systems: Semiconductors are critical in navigation and communication systems for aircraft, enhancing flight safety and efficiency.
  11. Power Grids: Semiconductor-based power electronics are used in smart grids to manage electricity distribution and enhance grid stability.
  12. Lighting Control Systems: Semiconductors are used in smart lighting systems to improve energy efficiency and provide advanced control options.
  13. Smart Metering: Semiconductors enable the functionality of smart meters, which monitor and report energy usage in real-time for efficient utility management.
  14. Environmental Monitoring: Semiconductor sensors are used in devices that monitor air and water quality, providing data for environmental protection efforts.

Uses of Semiconductors

1. Transistors

Transistors, made from semiconductor materials like silicon, act as switches and amplifiers in electronic circuits. They are essential in:
Mobile phones

2. Integrated Circuits (ICs)

Integrated circuits consist of multiple semiconductor devices on a single chip, used in:
Memory devices
Digital signal processors

3. Solar Cells

Solar cells convert sunlight into electrical energy using semiconductor materials, found in:
Solar panels
Solar chargers
Photovoltaic power plants

4. Light Emitting Diodes (LEDs)

LEDs are semiconductor devices that emit light when an electric current passes through them, used in:
Display screens
Indicator lights
General lighting

5. Power Electronics

Semiconductors are crucial in controlling and converting electric power, used in:
Power inverters
Motor drives
Power supplies


What is doping in semiconductors?

Doping involves adding impurities to a semiconductor to change its electrical properties, creating either n-type (electron-rich) or p-type (hole-rich) materials.

What is the role of electrons and holes in semiconductors?

Electrons are negatively charged particles, while holes are positively charged vacancies. Their movement under an electric field enables current flow in semiconductors.

What is an intrinsic semiconductor?

An intrinsic semiconductor is a pure semiconductor without any significant impurities. Its electrical properties are determined by the material itself.

What is an extrinsic semiconductor?

An extrinsic semiconductor is a doped semiconductor, where impurities are added to modify its electrical properties, making it either n-type or p-type.

What is a p-n junction?

A p-n junction is the boundary between p-type and n-type semiconductors, crucial for the operation of diodes, transistors, and other electronic devices.

What is a diode?

A diode is a semiconductor device that allows current to flow in one direction only, typically made from a p-n junction.

How do transistors work?

Transistors control the flow of current between two terminals using a third terminal (gate), acting as a switch or amplifier in circuits.

What is a semiconductor band gap?

The band gap is the energy difference between the valence band and conduction band in a semiconductor, determining its conductivity.

Why are silicon and germanium commonly used in semiconductors?

Silicon and germanium have suitable band gaps and can be easily doped, making them ideal for a wide range of electronic applications.

What is the significance of Moore’s Law in semiconductors?

Moore’s Law predicts the doubling of transistors on a semiconductor chip approximately every two years, driving advancements in technology.

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