Molecular beam epitaxy.

Molecular beam epitaxy is an ultrahigh vacuum technique for growing very thin epitaxial layers of semiconductor crystals. Because it is inherently a slow growth process, extreme dimensional control over both major compositional variations and impurity incorporation can be achieved. The result is that it has been possible, with one combination of lattice-matched semiconductors, GaAs and Alx-Gal-xAs, to demonstrate a large variety of novel single-crystal structures. These results have important implications for fundamental studies of the physics of thin-layered structures and for the development of new semiconductor electronic and optoelectronic devices.