When people hear the word “semiconductor,” the first material that comes to mind is silicon.

From modern computers and smartphones to solar cells, this single material forms the foundation of virtually every electronic device.

・Chemical symbol: Si

・Atomic number: 14

・The second most abundant element on Earth after oxygen, making up roughly 28% of the Earth’s crust

・Abundantly available as silica sand (SiO₂), keeping processing costs low

Silicon is inexpensive, stable, and readily forms an oxide layer — a well-balanced material that other semiconductor materials struggle to replace.

・Silicon has a diamond crystal structure held together by covalent bonds.

・Each atom has four valence electrons, which bond with neighboring atoms to form a strong crystal lattice.

・Because it is an indirect-gap semiconductor, its ability to absorb and emit light is weak, making it poorly suited to light-emitting devices.

While silicon’s electron mobility (speed) is lower than that of materials like GaAs, it far outperforms other materials in terms of stability and reliability.

Silicon’s greatest strength is its ability to naturally form an oxide layer (SiO₂).

This oxide layer:

・Has high electrical insulation, preventing leakage current.

・Serves as an ideal gate insulating layer in MOSFETs.

・Can also be used as a masking layer during photolithography.

This oxide-layer technology became the very foundation on which ICs and LSIs were built.

・Silicon has a high melting point (1,414°C) and is chemically stable.

・Techniques for growing single crystals (the Czochralski, or CZ, method) and processing wafers are well established.

・Wafer sizes have grown progressively larger — from 100mm to 200mm to 300mm — achieving both lower costs and higher production efficiency.

This makes silicon the semiconductor material best suited to mass production.

1.Logic ICs, CPUs, and memory → The base material for integrated circuits (MOSFETs, CMOS).

2.Power devices → Remains the dominant material in the low-to-medium voltage range (up to roughly 600V).

3.Solar cells → Monocrystalline and polycrystalline silicon cells account for roughly 90% of the market.

4.Sensors and MEMS → Used in sensing elements for acceleration, pressure, temperature, and more.

・Its low electron mobility makes it poorly suited to high-speed operation, lagging behind materials like GaAs and InP.

・Performance degrades at high temperatures and high voltages, as leakage current increases.

・It is unsuitable for light-emitting devices such as LEDs and lasers.

・As miniaturization progresses, quantum tunneling effects become an increasing problem.

As a result, silicon is increasingly being replaced by SiC and GaN in high-frequency and high-voltage applications.

・SOI (Silicon on Insulator) technology: Forms a silicon layer atop an insulating layer to reduce power consumption.

・FinFET and GAAFET structures: Give silicon a three-dimensional structure to help maintain performance.

・Si-Ge alloys: Improve electron mobility, benefiting communications and high-performance logic applications.

Continuing to push the evolution of silicon itself remains the lifeblood of the industry.

・While silicon’s limits are approaching, it is unlikely to disappear entirely.

・The industry is expected to move toward hybrid approaches — combining silicon with GaN or with optical devices.

・Silicon will continue to serve as a core material even in AI, autonomous driving, and IoT applications.

Even as new materials emerge, they are likely to ultimately be combined with silicon rather than replace it outright.

・Silicon is the most mature semiconductor material and remains at the center of foundational technology.

・Its key strengths are low cost, high stability, and ease of forming an oxide layer.

・It is poorly suited to high-speed, high-voltage, and optical applications, but ongoing technological advances continue to compensate for these weaknesses.

・Through continued improvement, hybridization, and optimization, silicon is set to remain the leading material for years to come.

1.What is the biggest reason silicon remains the dominant material?

2.In which areas does silicon struggle?

3.What does next-generation silicon technology look like?

 

 

Column Supervisor: Koji Kakumoto (Otis Group Co., Ltd.)

After studying abroad and working in planning and development at a trading company, he joined Otis Group Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as Representative Director, working to drive business growth and strengthen the organization.

 

This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.