Atomic layer epitaxy

Atomic layer epitaxy (ALE) or Atomic Layer Chemical Vapor Deposition (ALCVD), now more generally called Atomic Layer Deposition (ALD), is a specialized form of epitaxy that typically deposit alternating monolayers of two elements onto a substrate. The crystal lattice structure achieved is thin, uniform, and aligned with the structure of the substrate. The reactants are brought to the substrate as alternating pulses with "dead" times in between. ALE makes use of the fact that the incoming material is bound strongly until all sites available for chemisorption are occupied. The dead times are used to flush the excess material. It is mostly used in semiconductor fabrication to grow thin films of thickness of the atomic order.