Newly developed semiconductor microstructures can now guide light and electrons resulting in important consequences for state-of-the-art electronic and photonic devices. This volume introduces a new generation of epitaxial microstructures. Special emphasis has been given to atomic control during growth and the interrelationship between the atomic arrangements and the properties of the structures. - Atomic-level control of semiconductor microstructures - Molecular beam epitaxy, metal-organic chemical vapor deposition - Quantum wells and quantum wires - Lasers, photon(IR)detectors, heterostructure transistors