The regularities of ion synthesis of gallium oxide nanocrystalline inclusions by implantation of gallium and oxygen ions into dielectric Al2O3 films on silicon substrates and subsequent thermal annealing are considered. The composition of the implanted samples before and after annealing was investigated by X-ray photoelectron spectroscopy with layer-by-layer profiling. The formation of Ga-O chemical bonds was demonstrated, and after annealing gallium is predominantly in the fully oxidized state. According to X-ray diffraction data, the formation of β-Ga2O3 crystalline phase was confirmed. The study of photoluminescence of the synthesized samples revealed the presence of luminescence band, which is presumably caused by radiative recombination of donor-acceptor pairs.