Semiconductors are the materials which have a conductivity between conductors (generally metals) and non-conductors or insulators (such ceramics). Semiconductor can be compounds such as gallium arsenide or pure elements, such as germanium or silicon.
Semiconductor are used in almost all electronic devices. Their reliability, compactness, low cost and controlled conduction of electricity make them ideal to be used for various purposes in a wide range of components and devices. transistors, diodes, photo sensors, microcontrollers, integrated chips and much more are made up of semiconductors.
E.g.: Gallium arsenide, germanium, and silicon are some of the most commonly used semiconductors. Silicon is used in electronic circuit fabrication, and gallium arsenide is used in solar cells, laser diodes, etc.