The paper is devoted to the development of the technology for obtaining GaN epitaxial layers on silicon by the HVPE (Hydride Vapor Phase Epitaxy) method. Synthesis of gallium nitride directly on silicon is difficult to achieve due to the interaction at high temperatures between silicon and nitrogen, the release of the gallium in the form of drops, the deterioration of the surface of the substrate. Interaction can be diminished by using a buffer layer of AlN synthesized on the surface of the substrate under optimized conditions at the initial GaN layer growth stage. The synthesis of AIII-N/Si(111) layers was carried out in the (H2-HCl-Al-Ga- NH3) system in a quartz reactor at atmospheric pressure. Hydrogen was used as transport gas. The transport of Ga, Al precursors was carried out in a flow of hydrogen chloride. Ammonia was used as the nitrogen source. The phase composition and crystallographic properties were analyzed by X-ray diffraction (XRD). XRD patterns were recorded at Tallinn University of Technology on a Rigaku Ultima IV system using monochromatic Cu Kα radiation (λ= 1.5406 Å, 40 kV at 40 mA) and equipped with a D / teX Ultra silicon line detector in the 2θ (Bragg-Brentano ) Mode using a 2θ step of 0.04, and a counting time of 2-10 s / step, and sample rotation. Crystal phases were identified using data issued by the Joint Committee on Powder Diffraction Standards (JCPDS). The crystallite sizes and lattice constants were calculated using the Rigaku PDXL Version 1.4.0.3 software. The Debye-Scherrer formula was used to calculate the crystallite size. . The Debye–Scherrer formula was used to calculate the crystallite size (L): B(2θ)=Kλ/Lcosθ , where B is the peak width, K is the Scherrer constant, λ is the wavelength of the X-ray radiation, and θ is one-half of the diffraction angle The deposition of AlN layers was performed in the range 500 ÷ 1150 0C with the duration of 30 ÷ 600 sec. At temperatures lower than 800 0C, the layers are usually amorphous, can be easily removed from the surface of the substrate. In the AlN /Si structures obtained at 1100 0C for 40 sec, except for AlN and Si (a= 5.429 A), the following phases were found: Polymeric nitrogen (pN) (a = b = c = 3.503 A; α = β = γ = 900; Crystallite size (Cs) = 227A); Cristobalite-a (low) (a = b = 4.902 A, c = 6.8 A; α = β = γ = 900; Cs = 530 A); Quartz HP, syn (a = b = 4.55 A, c = 5.169 A, α = β = 900, γ = 1200; Cs = 1536 A). In the GaN layers grown at 10350C on AlN/Si structures (AlN layer deposited at 1100 0C), cubic modification of gallium nitride (a = 4.50 A), aluminum nitride (a = 4.298 A) were obtained, as well as Hexagonal quartz HP (a = 4.564 A; b = 5.420 A). Traces of pN in this GaN layer were not detected. GaN epitaxial layers were obtained on intermediate layers of AlN grown at temperatures higher than ≥ 1000 0C with a duration of 120 ± 40 sec and thicknesses in the order of 100 nm.