English: Figures 1-3 show images of 50 nm niobium (Nb) superconducting thin films [1] deposited at different temperatures and imaged with different magnification (a,b,c). Typical size of structural elements of Nb thin film is 20-100 nm. Nb thin film was fabricated using DC magnetron stuttering technique [2]. Nb was sputtered from 4N purity Nb target on single-crystal <001>-oriented SrTiO3 [3] substrates. Temperature of the substrate was 200°С (Figs. 1 а-с), 350°С (Figs. 2 а-с) and 500°С (Figs. 3 а-с). Imaging of the surface was done using high-resolution scanning electron microscope [4] JEOL JSM-7500FA in SEI regime. Superconducting properties of films shown in Figs. 1-3 were relatively moderate (a superconducting critical temperature [5] measured was below 6 K while it was expected to be about 9 K). Therefore, detailed investigation of physical properties, morphology and thin film growth mechanism for these films was not carried out. Nevertheless, growth mechanism that lead to such a developed surface structure is interesting by itself and images shown in Figs. 1-3 hold certain aesthetic value. Following mechanism of the structure formation is considered. Nb is a typical metal with BCC crystal structure [6] and lattice parameter a=0.33 nm while SrTiO3 substrate is single-crystal [7] insulator with perovskite structure [8] and lattice parameter 0.39 nm. Thus, Nb metallic thin film grows on insulating substrate via Volmer-Weber 3D island growth mechanism [9] and “tries” to adopt crystal structure and orientation of single-crystal substrate due to enhanced temperature. I.e. epitaxial-like growth is assumed [10]. Epitaxy and strong mismatch between crystal lattices of Nb and SrTiO3 substrate lead to formation of triangular mutually disoriented Nb islands at the early stages of thin film growth. At later stages of growth process these islands interconnect, i.e. percolation occurs [11], and bizarre structural elements of nanometer scale appear (butterflies, stars or snowflakes). Also, a fine structure on top of the islands can be recognized (the best seen in Figs. 1 a,b). This fine structure is a result of terraces formation and propagation during 2D Frank-Van-der-Merwe growth [12] of Nb on Nb (i.e. metal on metal thin film growth). Dependence of morphology of thin films on temperature of the substrate is a result of enhanced thermal activation of ad-atom migration and diffusion processes during the film growth at increased temperature. In general, increased temperature leads to higher degree of epitaxy and reduced density of crystal defects in thin film. These images were done during PhD research under supervision of professor Alexey Pan.