A superlattice is a structure made up of alternating layers of two or more different materials, typically semiconductors. These layers are usually just a few nanometers thick, creating a periodic arrangement that can enhance certain electronic and optical properties. Superlattices are often used in advanced electronic devices, such as lasers and transistors, to improve performance. The unique properties of superlattices arise from quantum mechanical effects, as the thin layers confine electrons and holes, leading to new energy band structures. This allows for the design of materials with tailored characteristics, making superlattices important in fields like nanotechnology and solid-state physics.