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GaN III-V nitride is a well-known semiconductor for short-wavelength light-emitting diodes with a direct band gap of 3.4 eV. But the lack of suitable substrates with low dislocation density remains some problems to development of high-performance optoelectronic devices based on III-nitride multilayers structures. The device characteristics of thin films have a large dependence on the substrate material because heteroepitaxial film becomes dominated by extended defects arising, first of all, from the interfacial mismatch. Here, for this reason, some attempts were made to solve this problem. Over fifty various inorganic crystals and their solid solutions have been considered in search for a replacement substrate. First of all, the structural data were analysed for oxides, silicates, borates, molybdates, tungstates, tantalates. This analysis was based on the existing structural and physico-chemical database for inorganic oxide compounds which was up-to-dated using the data from scientific journals. Among them, the main attention was paid to candidates from the viewpoint of phase stability, easy of growth and their physico-chemical properties. The epitaxial relations were examined for some crystallographic orientations of the GaN epicrystal and substrates like Al2O3, MgO, ZnO ZrO2, LiAlO2, YAlO3, LaAlO3, LiGaO2, LaGaO3, NdGaO3, KTaO3, LaTa3O9, LaTa7O19, Ca2LaTaO6, SrTiO3, Si, SiC, perovskite-, spinel- and wurzite-type structures. As a result, a correlation between the growth conditions, compositions, homogeneity and structural characteristics of these promising materials has been found.