Energy Band Theory

Energy Band Theory explains how electrons behave in materials, particularly semiconductors. In solids, electrons occupy energy levels that form bands. There are two main bands: the valence band (filled with electrons) and the conduction band (where electrons can move freely, allowing electricity to flow). The gap between these bands, called the bandgap, determines a material's electrical properties. In semiconductors, this bandgap is small enough that energy (like heat or light) can excite electrons from the valence band to the conduction band, enabling conductivity under certain conditions, which is crucial for electronic devices.