Glossary term
Semiconductor
A material whose electrical conductivity can be controlled by doping, fields, light, and temperature.
Definition
materialA semiconductor is a material with controllable electrical conductivity between that of a conductor and an insulator.
Semiconductors conduct through electrons and holes whose concentration can be controlled by doping, electric fields, light, temperature, and device geometry. They are the material foundation of diodes, transistors, integrated circuits, sensors, power electronics, LEDs, lasers, photodiodes, and photovoltaic devices.
Semiconductors such as silicon, germanium, gallium arsenide, gallium nitride, and silicon carbide have an energy band gap that allows their carrier population to be engineered. At low temperature an intrinsic semiconductor has few mobile carriers. Doping introduces donor or acceptor atoms that create n-type or p-type material, making electrons or holes the majority carriers.
When p-type and n-type regions meet, diffusion and electric field effects create a depletion region and a built-in potential. This p-n junction is the basis of rectifiers, photodiodes, LEDs, solar cells, and many transistor structures. External voltage changes the barrier and therefore controls current flow.
Engineering relevance
Semiconductor behaviour depends strongly on temperature, electric field, geometry, impurities, crystal defects, packaging, and heat removal. Leakage current, breakdown voltage, carrier mobility, switching speed, capacitance, noise, optical absorption, and junction temperature all matter in practical devices. Wide-bandgap semiconductors such as silicon carbide and gallium nitride are used where high voltage, high temperature, high frequency, or high power density is required.
In integrated circuits, semiconductors are patterned into billions of devices using lithography, deposition, implantation, etching, and metallization. In power electronics, the same physics is used at larger scales where thermal resistance, switching loss, safe operating area, and insulation coordination dominate the design.
Common mistakes
A common mistake is describing a semiconductor simply as a weak conductor. Its value is not moderate conductivity but controllable conductivity. Another is ignoring temperature: leakage, threshold behaviour, breakdown limits, optical response, and lifetime can change dramatically with junction temperature. A strong semiconductor review states material system, doping, device structure, operating voltage, current density, temperature range, switching or optical conditions, and packaging limits.