A method of epitaxy that is carried out in ultrahigh vacuum. It is a thermal evaporation technique in which the elements to be deposited are evaporated from ovens and impinge on the substrate where they are deposited in crystalline order. The substrate wafer is rotated to ensure a uniform growth rate across the wafer. Under suitable conditions the process can be controlled to produce almost any required epitaxial layer composition, thickness, and doping level with a resolution of virtually one atomic layer, to a high degree of accuracy and uniformity across the wafer. Disadvantages are the high-vacuum requirements, complex and costly equipment, and the slow growth rate of the epitaxial layer.