The presented article concerns the comparison between two different zinc-oxide structures - bulk crystals and polycrystalline thin films. Bulk crystals were grown by a Bridgman method. For thin-film production, a sol-gel spin-coated method was chosen. A part of thin layers samples was annealed in 600 $$^{o}$$ o C to induce recrystallization. The morphological and structural properties of all samples were investigated using various microscopy techniques, X-ray diffraction, and Raman spectroscopy. Confocal and scanning electron microscopy, as well as XRD, was used to estimate the influence of the recrystallization process on the morphology of the samples. The Raman vibrations in different scattering geometries were determined using polarized Raman spectra. What is more, in the case of the non-annealed sol-gel layer, the localized reorientation of crystallites was observed, using Raman microscopy. The morphology of the samples was compared to their optical properties, which were investigated by exploiting UV-Vis absorption and photoluminescence spectroscopy. Absorption spectroscopy allowed us to estimate the energy bandgap for different types of ZnO layers and to compare the values obtained for the ZnO crystal structure obtained by the Bridgman method. The photoluminescence and Raman spectroscopy were used to determine the possible defects correlated with the growth conditions.

Preparing structures with the sol-gel method often requires control of the basal plane of crystallites, crystallite structures, or the appearance of the voids. One of the critical factors in the formation of a layer are additives, such as aminoalcohols, which increase the control of the sol formation reaction. Since aminoalcohols differ in boiling points and alkalinity, their selection may play a significant role in the dynamics of structure formation. The main aim of this work is to examine the properties of ZnO layers grown using different aminoalcohols at different concentration rates. The layers were grown on various substrates, which would provide additional information on the behavior of the layers on a specific substrate, and the mixture was annealed at a relatively low temperature (400 °C). The research was conducted using monoethanolamine (MEA) and diethanolamine (DEA). The aminoalcohols were added to the solutions in equal concentrations. The microscopic image of the structure and the size of the crystallites were determined using micrographs. X-ray diffractometry and Raman spectroscopy were used for structural studies, phase analysis and to establish the purity of the obtained films. UV-vis absorption and photoluminescence were used to evaluate structural defects. This paper shows the influence of the stabilizer on the morphology of samples and the influence of the morphology and structure on the optical properties. The above comparison may allow the preparation of ZnO samples for specific applications.

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Zinc oxide (ZnO) is one of the wide-bandgap semiconductors, which may be useful in a plethora of electronic, optical, piezoelectric, and scintillating applications. The following article consists in a structural and luminescence analysis of ZnO microfilms grown on a sapphire substrate with a sol–gel method. The films were annealed at different temperatures. The structures were investigated with the XRD and Raman methods, by which the influence of the substrate on the structure of the film was determined. The luminescence of films was investigated with room-temperature fluorescence, radioluminescence, and thermoluminescence.