[en] We describe synthesis of submicron Y₃Fe₅O₁₂ (YIG) films sputtered on GaAs-based substrates and present results of the study of ferromagnetic resonance (FMR), spin wave propagation and interaction between spin excitations and 2D electrons in interface layer in YIG/AlO_x/GaAs-heterostructures. It is found that the contribution of the relaxation process to the FMR linewidth is about 3.6%–6.6% of the linewidth . The main contribution to the FMR linewidth of sputtered YIG films is given by a magnetic profile inhomogeneity. Transistor structures with two-dimensional electron gas (2DEG) channels in AlO_x/GaAs interface governed by YIG-film spin excitations are designed. An effective influence of spin excitations on the current flowing through the GaAs 2DEG channel is observed. It is found that the light illumination results in essential changes in the YIG-film FMR spectrum of transistor structures—an increase of the 2DEG current induced by light leads to an inverse effect, which represents essential changes in the FMR spectrum. (paper)