Superlattices are structures made by stacking alternating layers of two or more different materials, typically semiconductors. These layers are usually just a few nanometers thick, creating a periodic structure that can enhance certain electronic and optical properties. The unique arrangement allows for the manipulation of electron behavior, leading to applications in advanced electronics and photonics. The properties of superlattices arise from quantum mechanics, as the thin layers confine electrons and holes, resulting in quantized energy levels. This phenomenon can be utilized in devices like quantum wells, laser diodes, and transistors, making superlattices important in modern technology and materials science.