What Are Semiconductors? (Uses, Types, How It Works, Industry Insights)

what-are-semiconductors
What Are Semiconductors?

Semiconductors are materials with electrical conductivity that fall between conductors (like copper) and insulators (like glass). This unique property allows them to manage the flow of electrical current, making them crucial in various electronic devices. Commonly made from silicon, most semiconductors can also be crafted from materials like germanium and gallium arsenide.

Semiconductors play an important role in modern technology, underpinning the functionality of computers, smartphones, and numerous other digital devices that shape contemporary life. As fundamental components in global technological advancements, semiconductors drive economic growth and are integral to the strategic development of industries worldwide.

They are at the heart of many of the world’s largest semiconductor manufacturing firms, which lead the market with advanced manufacturing processes. This foundational industry not only powers technology firms globally but also meets international demands, establishing semiconductors as essential elements in the global tech landscape.

Table of Contents

What Materials Are Used to Make Semiconductors?

Most semiconductors today are made of silicon, due to its abundance and excellent semiconductor properties when processed. 

Germanium was used in early semiconductor devices and continues to be used for certain applications due to its high charge carrier mobility. Other materials like gallium arsenide are also used, particularly in high-speed devices and solar cells, due to their superior electron mobility compared to silicon. 

Additionally, there are compound semiconductors, such as indium phosphide and gallium nitride, which offer advantages in specific applications like LEDs and laser diodes.

Semiconductors vs. Conductors vs. Insulators

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Conductors

Materials like copper, silver, and aluminum allow electrons to flow freely across their structures, leading to high electrical conductivity. They do not control the flow of electrical current, making them unsuitable for use in applications where the control of current is necessary, such as in transistors.

Insulators

Materials such as rubber, glass, and plastic have very low electrical conductivity. They do not allow the free flow of electrons, effectively blocking the passage of electrical current. This makes them ideal for preventing unwanted current flow, serving as protective barriers in electrical devices.

Semiconductors

Stand in the middle of this spectrum. Under certain conditions, they can either conduct electricity or act as insulators. This dual ability is manipulated in electronic devices through the introduction of impurities in a process called "doping," which modifies the electrical properties of semiconductors in a controlled way to either increase or decrease their conductivity.

How Do Semiconductors Work?

Semiconductors operate based on the movement of electrons within a crystal lattice of atoms. The unique property of semiconductors lies in their energy band structure, which includes a valence band filled with electrons and a conduction band that is typically empty. The energy gap between these bands, known as the bandgap, is crucial; it is small enough in semiconductors that electrons can move from the valence to the conduction band under certain conditions, such as the addition of energy (heat or light).

Doping: Modifying Conductivity

Doping involves introducing impurities into an intrinsic (pure) semiconductor to change its electrical properties. This process adds dopant atoms that have more or fewer electrons than the atoms they replace. 

There are two types of doping:

  • N-type Doping: Adds atoms that have more electrons than the semiconductor atoms, typically five electrons in their outer shell compared to silicon's four. This extra electron is easily excited into the conduction band, increasing the material's conductivity. Phosphorus or arsenic are common dopants used to create N-type semiconductors.
  • P-type Doping: Involves adding atoms with fewer electrons (typically three) in their outer shell, creating "holes" or the absence of electrons in the semiconductor's structure. These holes can move through the lattice, effectively carrying positive charge. Boron is a typical P-type dopant.

Electron and Hole Flow in Semiconductors

In N-type semiconductors, the extra electrons provided by doping increase the number of charge carriers, enhancing conductivity. When voltage is applied, these electrons flow through the material, creating an electric current.

Conversely, in P-type materials, doping creates holes. When these semiconductors are placed in an electric field, the holes move toward the negative terminal, behaving as though they are positively charged particles. This movement of holes is also a form of electrical current.

When N-type and P-type materials are joined, they form a PN junction—a cornerstone of semiconductor devices like diodes and transistors. At this junction, electrons and holes combine, creating a depletion zone that acts as an insulator until sufficient voltage is applied. This arrangement allows the semiconductor device to control the flow of electrons, switching and amplifying electronic signals, which is fundamental in all modern electronics.

What Are the Types of Semiconductors?

Intrinsic vs. Extrinsic Semiconductor

Intrinsic semiconductors are pure forms of semiconductor materials without any significant impurities added. Silicon and germanium are common examples, which exhibit a very controlled form of conductivity at room temperature. 

Intrinsic semiconductors are characterized by their pure elements, undoped, crystalline forms, where the number of electrons is equal to the number of holes. The conductivity of intrinsic semiconductors is generally poor because it relies solely on the thermal excitation of electrons to cross the band gap from the valence band to the conduction band.

Meanwhile, extrinsic semiconductor is created by adding impurities to the intrinsic semiconductor material in a process called doping. This process introduces free charge carriers, either electrons or holes, enhancing the material’s conductivity. Extrinsic semiconductors are classified into two types based on the nature of the impurity added: N-type and P-type.

N-type and P-type Semiconductor

In N-type semiconductors, dopants that have more electrons than the host semiconductor material (such as phosphorus in silicon) are added. These extra electrons are free to move and contribute to electrical conductivity. The term 'N-type' comes from the negative charge of the electron. These semiconductors are characterized by the movement of electrons as the primary charge carriers.

On the other hand, P-type semiconductors are made by doping the semiconductor material with atoms that have fewer electrons than the host material (such as boron in silicon). This doping creates "holes" or spaces where an electron is missing in the electron structure, and these holes can accept electrons. The movement of these holes, which effectively act as positive charge carriers, defines the conductivity in P-type semiconductors.

What Are Compound Semiconductors?

Compound semiconductors are composed of two or more elements. Unlike elemental semiconductors like silicon (Si) and germanium (Ge), compound semiconductors are made from combinations such as gallium arsenide (GaAs), indium phosphide (InP), and gallium nitride (GaN).

Applications of Compound Semiconductors

  • Gallium Arsenide (GaAs): Widely used in high-speed electronic devices, including RF and microwave applications, due to its higher electron mobility than silicon.
  • Indium Phosphide (InP): Utilized in high-speed and high-frequency electronics and photonics technologies. It is particularly important in the manufacture of laser diodes and photodetectors.
  • Gallium Nitride (GaN): Known for its use in LED technology to produce blue light. GaN transistors are also widely used in satellite communications, military applications, and more recently in power electronics due to their high heat capacity and power efficiency.

What Are Semiconductors Used For?

what-are-semiconductors

Consumer Electronics

Semiconductors form the core of microprocessors and memory chips that can be found in personal computers, smartphones and other mobile devices. They enable the functioning of CPUs, GPUs, and DRAM, which are essential for processing and storage tasks in these devices.

Modern home appliances such as refrigerators, washing machines, and microwaves utilize microcontrollers and sensor-based technologies are also powered by semiconductors to enhance functionality and energy efficiency.

Renewable Energy

Semiconductors are crucial in converting solar energy into electrical energy. Materials like silicon are used in solar panels and photovoltaic cells due to their effective energy conversion properties. Advances in semiconductor technology have significantly increased the efficiency and decreased the cost of solar power equipment.

Automotive Industry

Semiconductors are crucial electronic components that make recent advancements in automotive possible. Advanced driver-assistance systems (ADAS) rely on semiconductors for sensors that help with parking assistance, collision avoidance, and more. Semiconductor-based displays in dashboards provide critical information and enhanced interaction for drivers and passengers.

Semiconductors are also key in managing power control and battery management systems in electric vehicles. They improve the efficiency of power usage and enhance the vehicle's range and performance.

Telecommunications

Semiconductors enable the functionality of smartphones, routers, and switching systems which are the backbone of modern telecommunications infrastructure. They are essential for high-speed data transmission and reliable connectivity in cellular networks and the internet.

Healthcare

Semiconductor technology is integral to the operation of medical imaging and diagnostic equipment such as MRI machines, CT scanners, and ultrasound devices. Semiconductors help process complex data and generate detailed images that are crucial for accurate diagnosis.

Semiconductors also play a role in portable medical devices that have recently become more and more accessible like glucose monitors and wearable health trackers, facilitating continuous monitoring of health conditions with improved accuracy and connectivity.

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The Semiconductor Industry

Brief History of the Semiconductor Industry

The semiconductor industry began its rapid development with the invention of the transistor in 1947 by Bell Labs. This revolutionized electronic circuits by replacing bulky and less reliable vacuum tubes. The introduction of the integrated circuit (IC) by Jack Kilby and Robert Noyce in the late 1950s marked another milestone, leading to the development of microprocessors in the 1970s and setting the foundation for modern computing and electronics. Over the decades, advancements in materials science, photolithography, and engineering have enabled the continuous miniaturization and increased functionality of semiconductor devices.

Major Players and Geographic Hubs

The industry is dominated by several key players, each specializing in different segments such as microprocessors, memory, and foundries. Notable semiconductor companies include Intel, Samsung, TSMC, Qualcomm, and Broadcom. Each plays a critical role in developing and manufacturing the advanced semiconductor components needed for a wide array of products.

The United States, particularly Silicon Valley, has historically been a central hub due to its ecosystem of innovation and access to venture capital. East Asia, particularly Taiwan, South Korea, and Japan, are also crucial, with Taiwan's TSMC and South Korea's Samsung leading in foundry and memory chip production, respectively. Additionally, mainland China is rapidly growing as a significant player in the semiconductor industry, driven by substantial investments from the government to foster self-reliance in technology.

Miniaturization

As devices become increasingly smaller and more powerful, the industry continues to push the limits of miniaturization. The development of 5nm and even 3nm process technologies is underway, which allows for more transistors on a single chip, enhancing performance and energy efficiency.

Integration of Semiconductor Technology

There is a growing trend towards the integration of diverse semiconductor technologies into single packages, known as system-on-a-chip (SoC) and package-on-package (PoP) integrations. These solutions combine processing, memory, and connectivity components into compact, highly efficient units.

Artificial Intelligence (AI)

Semiconductors are at the heart of AI development, from data centers that process AI algorithms to the edge devices that use them. The industry is increasingly focused on creating specialized AI chips that are optimized for machine learning tasks.

Advanced Materials

Beyond silicon, new materials such as gallium nitride (GaN) and silicon carbide (SiC) are being used for specific applications where higher efficiency, faster switching times, and greater heat tolerance are required.

Conclusion

Semiconductors have become the backbone of modern technology, integral to everything from consumer electronics to advanced healthcare systems. They empower our devices with enhanced functionality and connectivity, drive innovations in renewable energy, and are crucial to the development of electric vehicles and medical diagnostics. 

As technology progresses, the demand for smaller, faster, and more efficient semiconductors grows, keeping them at the forefront of advancements in the Internet of Things, artificial intelligence, and next-generation networking. The ongoing evolution of semiconductor technology continues to shape our technological landscape, proving essential in both current applications and future innovations.

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— Originally Written by Donaven Leong —

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