semiconductorsare

Semiconductors are materials whose electrical conductivity lies between that of metals and insulators and can be modified by temperature, impurities, or electric fields. The most widely used semiconductor is silicon, though germanium, gallium arsenide, and silicon carbide are also important. Their behavior is governed by the electronic band structure and the presence of a suitable band gap that enables control of charge carriers.

Doping introduces impurities to create n-type or p-type semiconductors, increasing the concentration of electrons or holes, respectively. When p-type and n-type regions are joined, a p-n junction forms, enabling diodes and, with additional structures, transistors. The transistor is foundational for modern electronics, acting as a switch or amplifier and enabling integrated circuits.

Manufacturing semiconductors involves transforming raw materials into pure crystals, growing wafers, and applying microfabrication steps such as diffusion, ion implantation, oxidation, lithography, and metallization. Cleanroom processes and precise control of defects determine device performance and yield. The history of semiconductors includes the invention of the transistor in 1947, which spurred the development of integrated circuits and the digital age.

Applications span computing, telecommunications, power electronics, photovoltaics, and optoelectronics. Semiconductors enable microprocessors, memory devices, sensors, LEDs, and solar cells. Trends in the field include the use of wide-bandgap materials like silicon carbide and gallium nitride for high-power and high-frequency electronics, as well as advances in flexible, 2D, and nanoelectronics. Key challenges involve heat dissipation, defect control, device variability, and supply-chain considerations.