Over the last 25 years, the performances of semiconductor devices have improved greatly; this book describes the science and technology that have made these advances possible. While mainstream silicon memory and microprocessor chips still work with uniform silicon as the starting point, the whole of both electronic and optical communication relies on multilayer semiconductor structures. The book provides a unified overview of the devices, including the relevant quantum physics and the key breakthroughs in materials science and technology. It is suitable as a text for undergraduates and graduates in physics, materials sciences, or electronics, as well as researchers in the field.