Vapour phase epitaxial growth of monocrystalline layers of semiconductor materials on a substrate is done based on organometallic compounds in the reactor at under-pressure conditions. Vapour phase epitaxy was originally developed for growing silicon and gallium arsenide, and now it is used to grow most of the semiconductor materials used in micro- and optoelectronics. Mixed vapour enters the reactor where the substrates (thin slices of a monocrystal) are placed. In the case of silicon growing, the core component in the mixed vapour is silicon tetrachloride SiCl₄ or silane SiH₄; when growing arsenide and phosphidem, the main components are the respective metal alkyls (Ga(CH₃)₃, Al(CH₃)₃, Ga(C₂H₅)₃, In(C₂H₅)₃), as well as arsine AsH₃ and phosphine PH₃. The vapour mixture at high temperature decomposes in a pyrolytic way near the growth surface and the third group elements interact with the fifth group elements to form A^IIIB^V compounds. This results in the layer-by-layer deposition of semiconductor compounds. Vapour epitaxy is used to grow GaAlAs/GaAs heterostructures with quantum wells for injection lasers, GaAs/GaAlAs heterostructures with selective doping, heterostructures with quantum dots, wide-band GaN-based semiconductor materials to manufacture blue and green LEDs and short-wavelength lasers.