SEMICONDUCTOR FUNDAMENTALS · THE FOUNDATION
What Is a Semiconductor?
A practical introduction to the materials, transistors and chip categories at the center of modern electronics.
A semiconductor is a material whose electrical conductivity can be controlled. By adding tiny amounts of other elements and arranging regions with different electrical properties, engineers create transistors—the switches used to process, store and manage information.
Why silicon can act as a switch
Pure silicon conducts electricity less readily than a metal but more readily than an insulator. Manufacturers deliberately add impurities in a process called doping to create n-type regions with extra electrons and p-type regions with mobile positive charges, or holes. Where these regions meet, electric fields can control the movement of charge. This controllability makes diodes and transistors possible.
From transistor to integrated circuit
A transistor can switch a current or amplify a signal. An integrated circuit combines transistors with interconnects and other components on a small piece of semiconductor material called a die. Modern chips may contain billions of transistors, but their purpose is still rooted in controlled electrical switching. Photolithography, deposition, etching, ion implantation and polishing build the structures layer by layer on a wafer.
The major semiconductor categories
Logic chips perform calculations and control operations. Memory chips store data. Analog chips handle continuously varying signals, while power semiconductors manage electricity at higher voltages and currents. Sensors convert physical phenomena such as light, pressure or motion into electrical information. Many electronic systems combine several of these categories.
Why semiconductors matter
Semiconductors sit between software and the physical world. They determine how quickly an AI model can run, how much energy a data center consumes, how an automobile controls its powertrain and how a smartphone communicates. The industry therefore depends on a connected chain of design tools, intellectual property, wafer fabrication, equipment, materials, packaging and testing.
Why this matters for Japan
Japan’s importance is clearest when the semiconductor industry is viewed as a complete production system. Japanese companies hold important positions in silicon wafers, photoresists, specialty chemicals, manufacturing equipment, precision processing, testing, power semiconductors and image sensors. Shin-Etsu Chemical and SUMCO supply silicon wafers, while companies including Tokyo Electron, Advantest and DISCO support fabrication and test. Japan therefore remains influential even when the final chip is manufactured elsewhere.
Frequently asked questions
Are all semiconductors made of silicon?
No. Silicon is dominant, but silicon carbide, gallium nitride, gallium arsenide and other compound semiconductors are important for power, radio-frequency and optoelectronic applications.
Is a semiconductor the same as a chip?
Not exactly. Semiconductor describes the material or device class; chip usually means a packaged integrated circuit or its silicon die.
Why are chips made on circular wafers?
Single-crystal silicon is grown as a cylindrical ingot and sliced into circular wafers, which provide a flat, highly controlled surface for batch fabrication.
Official sources
Last reviewed: August 2026. SemiStructure provides independent educational material; specifications and product roadmaps can change.
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