Abstract: Silicon-on-sapphire structures serve as a base for the production of radiation-resistant integration circuits, which are very important for space industry, nuclear energetics, and the military sphere. The authors study the silicon-on-sapphire hetero-epitaxial mechanism for the subsequent creation of low-defectiveness transistor structures. Using the Rutherford backscattering, the authors study epitaxial layers of silicon, grown on sapphire substrate. Using the Auger analysis, the authors define the composition and the depth of the transitional layer of silicon-sapphire. The authors ascertain that silicon-to-sapphire bond is performed through tetrahedral sited oxygen. Defectiveness growth can be observed in the regions of spectrum of epitaxial layers, corresponding to the transitional region between the silicon layer and the sapphire substrate, and contributing to ion channeling. Account of an irregular character of the silicon-sapphire transition allows establishing causal link between the charge on the silicon-on-sapphire structure border and leakage current of field emission transistor. The authors develop the method of creation of a semiconductor device with improved parameters both in leakage currents and in structure defects density.