Abstract. The comparative analysis of optical characteristics inherent to Er 2 O 3 /SiC and Er 2 O 3 /por-SiC/SiC structures has been performed. It has been shown that, regardless the substrate on which the Er 2 O 3 film is formed, an increase in the rapid thermal annealing time leads to an improvement in the oxide film composition, with the composition of the Er 2 O 3 film approaching to the stoichiometric one. At the same time, introduction of an additional porous SiC layer leads to a blurring of the oxide film/substrate interface and broadening the photoluminescence band measured in this structure.