Аннотация:According to current ideas, there are two possible reasons for the increase in amplitude of fluctuations of the surface potential of a semiconductor under irradiation: 1) increase of the concentration of coulomb centers in the oxide near the Si-SiO2 interface, or 2) local reconstruction of the valence bonds in the transition region Si-SiO2 which leads to the generation of defects of the dipole type. To determine which of these two mechanisms plays a dominant role in the increase of the surface potential of the surface of silicon under irradiation, the authors carried out a comparative study of the effect of BTS+ (positive bias at the gate) and irradiation on the magnitude of the density of surface states near the bottom of the conduction band and electron mobility in the surface region of Si. The studies were carried out using MIS transistors with an insulating gate based on silicon KDB-20 with surface orientation (100). The electron mobility was determined by Hall’s method. The density of surface states near the forbidden gap was also determined. From the results the conclusion can be drawn that the most important process is the radiation-stimulated local reconstruction of the atomic surface layer of the oxide.