LED chip/die

An LED chip/die is a miniature semiconductor device fabricated on a substrate (typically sapphire, silicon carbide, or gallium arsenide) using epitaxial growth techniques. It consists of multiple semiconductor layers forming p-n junctions that emit photons when forward-biased. The chip includes active regions, electrodes, and sometimes phosphor coatings for wavelength conversion. As the fundamental light-emitting element in LED packages, it determines spectral characteristics, efficiency, and thermal performance.

Electroluminescence in semiconductor materials: When forward voltage is applied across the p-n junction, electrons and holes recombine in the active region, releasing energy as photons. The wavelength (color) is determined by the bandgap energy of the semiconductor materials (e.g., InGaN for blue/green, AlInGaP for red/yellow).