A comprehensive study of structural and optical properties of ZnO bulk crystals and polycrystalline films grown by sol-g
- PDF / 3,127,910 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 43 Downloads / 238 Views
A comprehensive study of structural and optical properties of ZnO bulk crystals and polycrystalline films grown by sol‑gel method Ewelina Nowak1 · Miroslaw Szybowicz1 · Alicja Stachowiak1 · Wojciech Koczorowski1,2 · Detlev Schulz3 · Kazimierz Paprocki4 · Kazimierz Fabisiak4 · Szymon Los4 Received: 13 April 2020 / Accepted: 7 June 2020 © The Author(s) 2020
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 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. Keywords ZnO · Sol-gel · Raman microscope · Structural study · Spectroscopy
1 Introduction For the past few decades, dramatic advances in the research focused on finding and preparing the best materials for optoelectronics have been noticed. Due to their wide, direct bandgap, II-VI compounds seem to be perfect candidates for the application in innovative electronics. Even nowadays these materials are used in light-emitting devices in the short-wavelength region of the visible range [1]. * Miroslaw Szybowicz [email protected] 1
Faculty of Materials Engineering and Technical Physics, Poznan University of Technology, Piotrowo 3, 60‑965 Poznan, Poland
2
Center for Advanced Technology, Adam Mickiewicz University, Umultowska 89C, 61‑614 Poznan, Poland
3
Leibniz-Institut fur Kristallzchtung, Max‑Born‑Strasse 2, 12489 Berlin, Germany
4
Institute of Physics, Kazimierz Wielki University, Weyssenhoffa Sq. 11, 85‑072 Bydgoszcz, Poland
Additionally, because of high-voltage blocking capability, high-temperature operation and high switching frequencies, most of the wide bandgap semiconductors may be feasibly used in power electronics [2]. One of the most promising II–VI semiconductors is zinc oxide (ZnO). ZnO in its most thermodynamically stable form, wurtzite-typ
Data Loading...
