The factors that are important for producing epitaxial layers of high purity crystalline perfection are the surface of a substrate, material deposition rate and the process temperature. Epitaxial films can grow from gas, liquid or solid phase, and therefore vapour phase epitaxy, liquid phase epitaxy, solid phase epitaxy and molecular beam epitaxy are distinguished.

A monocrystalline substrate sets up the parameters for film growth, so the crystalline structure and the epitaxial film orientation are the same as those of the substrate. This distinguishes epitaxial growth from thin film growth, when polycrystalline or amorphous films grow even on monocrystalline substrates. If the composition of the film and the substrate are the same, the process is called homoepitaxy, if they are different, it is called heteroepitaxy.

Epitaxial growth is widely used in nanotechnology and in the production of semiconductor devices to create layers of semiconductor materials with high crystalline quality, such as silicon, germanium, gallium nitride, gallium arsenide and indium phosphide.