a grown crystal layer with the same crystallographic orientation as the substrate crystal wafer. Also called epi.
a single crystal layer formed on top of a single crystal substrate. An epitaxial layer will typically have a different doping level and or type than the substrate upon which the epitaxial layer is formed. In some cases the epitaxial layer may be a completely different type of material than the substrate upon which it is grown. If the substrate and the epitaxial layer are both the same element or compound then the process is homoepitaxy and if the epitaxial layer and the substrate are different elements or compounds then the process if hetroepitaxy. see also, crystalline.
A layer of semiconductor material having the same crystalline orientation as that of the substrate upon which it is grown.
A thin precisely doped monocrystalline layer of silicone grown onto a heavily doped thick wafer, and into which the semiconductor junctions are diffused. In conventional integrated circuit processing, the thick wafer is "p" doped, and the epitaxial layer is "n" doped.