A comprehensive study of structural and optical properties of ZnO bulk crystals and polycrystalline films grown by sol-gel method

Abstract

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.

CMOS Compatible Al‐Doped ZnO Sol–Gel Thin‐Film Properties

“…The frequencies of the silent B1 (low) and B1 (high) modes have been calculated as 260 and 540 , respectively. [ 42,43 ] In general, the silent B1 mode is inactive in the perfect crystalline ZnO bulk structure. This mode is related to the phonon vibrations of ZnO and can be activated in a disordered structure.…”

Microscopic Study of Bovine Serum Albumin Adsorption on Zinc Oxide (0001) Surface

“…The Raman spectra shows typical bands corresponding to C plane of bulk ZnO. [ 24 ] Fingerprint of BSA could not be detected, most likely due to very small thickness of the adsorbed layer as shown by atomic force microscopy (AFM) measurements. Spectroscopy of such thin layers of biomolecules is extremely challenging.…”

Structural, Morphological, Optical, Luminescent and Magnetic Properties of Nanostructured ZnO Thin Film

“…It is observed that E1 mode does not appear for ZnO thin film, favoring the growth of ZnO thin film along c-axis. The peak observed at 1110 cm -1 and 2890 cm -1 corresponds to A1 (2LO) mode and organic residue (CH3 stretching), (does not decompose completely) respectively [60].…”