Yıldız, Fevkani; Mobtakeri, Soheil; Akaltun, Yunus; Kundakçı, Mutlu; Gür, Emre

In this study, thin films of CuO and Cu2O semiconductors were grown on n-type Si (100) and glass substrates by DC magnetron sputtering method in a controlled manner. X-ray Diffraction (XRD) measurements have confirmed that only CuO and Cu2O phases appeared in the respected films. The bandgap values for the CuO and Cu2O thin films are 2.05 and 2.64 eV, respectively, as confirmed by absorption measurements, respectively. When considering photodetector performances, CuO-based thin film has exhibited better responsivity and photosensitivity (Iph/Id) values, with 0.33 A/W and 516 %, respectively. To further improve the photodetector performances, the CuO and Cu2O thin films were sulfurized for 30 min. The sulfurization process has shown that grain boundaries are reduced, and crystal sizes have increased in materials by converting CuO to CuSO4 and Cu2O to Cu2S with minor CuS phases. The bandgaps of the samples have exhibited a reduction, 1.90 eV for CuSO4, and 2.25 eV for Cu2S. Electrical tests on photodetectors have revealed that sulfurized materials have reduced dark current, increased photosensitivity by up to 743 % with larger detectivity for Cu2S sample. Furthermore, improvements in ideality factors and rectification ratios indicate that device performance is significantly improved by sulfurization. In conclusion, the sulfurization process has demonstrated significant improvements in the performance of CuO-based photodetectors by enhancing the responsivity and photosensitivity, making them more efficient for practical applications.

Çayır Taşdemirci, Tuba

Zinc oxide (ZnO) thin films were synthesized using the Successive Ionic Layer Adsorption and Reaction (SILAR) method to investigate the effects of film thickness, annealing temperature, and precursor molarity on their structural, morphological, and optical properties. A series of ZnO films were prepared by varying the number of SILAR cycles (25–40), annealing temperatures (200–350 °C), and molarities (0.05–0.15 M). Structural characterization via X-ray diffraction (XRD) revealed that all films exhibit a polycrystalline hexagonal wurtzite structure with (002) as the preferred orientation, and crystallinity improved with increasing thickness, temperature, and molarity. Scanning Electron Microscopy (SEM) images confirmed homogeneous surface coverage with a flower-like morphology, while Energy Dispersive X-ray Spectroscopy (EDAX) analysis showed that the Zn/O ratio increased with all three parameters. Optical properties assessed by UV–Vis spectroscopy indicated a reduction in optical band gap values from 3.65 eV to 2.83 eV, correlating with enhanced crystallinity and reduced defect densities. The results demonstrate that increasing precursor molarity has a more pronounced effect on film quality compared to thickness and annealing temperature. This study provides a comprehensive analysis of parameter-dependent growth behavior, enabling the optimization of ZnO thin films for applications in optoelectronic devices.

Acar, M.T.; Çomaklı, O.; Yazıcı, M.; Arslan, M.E.; Yetim, A.F.; Çelik, A.

This comprehensive study investigates the corrosion and biocompatibility performances of boron-doped TiO2 nanotubes (TNT) synthesized on Ti6Al4V alloy produced by the selective laser melting (SLM) process. Structural analysis reveals a consistent reduction in nanotube diameter across varying boron doping levels (0.05 - 2 M boric acid doping), with B4-TNT exhibiting the smallest diameter at 190 nm. Boron incorporation induces phase transformation and decreases in diameter of nanotubes, influencing the material's structural properties. Corrosion resistance assessments indicate a significant enhancement, with B4-TNT demonstrating the highest polarization resistance (Rt = 2849.03 kΩ.cm2). The observed improvements are attributed to the combination of reduced nanotube diameter, altered phase structure, and increased polarization resistance, collectively contributing to enhanced corrosion resistance. Biocompatibility experiments conducted with human fibroblast cells (HDFa) reveal that B-doped TNTs foster increased cell viability compared to undoped TNT and uncoated alloy surfaces. These findings underscore the potential of boron doping as a strategic approach to improve corrosion resistance and enhance the biocompatibility of Ti6Al4V implants. This study provides valuable insights for advancing materials in biomedical applications with improved structural, corrosion-resistant, and biocompatible properties.

Zorlu, Rabia; Özdokur, K. Volkan; Acımert, Özlem Baran; Demir, Zeynep; Çağlar, Bülent; Çırak, Çağrı; Koçak, Süleyman

In this study, the hydrothermal surface modification of galvanized steel was performed on the substrate without any precursor ion for the first time to achieve a photocatalytic activity under UV light irradiation. The structural, morphological and optical properties of the modified and bare samples were examined by XRD, SEM-EDX, XPS, FTIR, UV-DRS and PL analyses. Electrochemical and wettability properties were determined with potentiostat and contact angle goniometry, respectively. The photocatalytic performances of surface modified galvanized steel samples were also investigated and comparatively evaluated by photo-degradation of quinoline yellow dye under UV light irradiation. Upon the doping silver ions into the structure, the photocatalytic degradation efficiency of fabricated composite material was determined as 100 % after the periods of 65 min. To the best of our knowledge this study is the first study dealing with photodegradation of quinolone yellow by using modified galvanized samples. The modified galvanized steel samples exhibited 96.1 % of its initial activity after 5 cycles. The surface modification by hydrothermal treatment improved the electrochemical properties of galvanized steel.

Karadeniz, Sibel Morkoç; Yeşilyurt, Merve Özturan

In this study, zinc oxide (ZnO) micro-nano rods were synthesized on unseeded, bare glass substrates by simple and one-pot chemical method at two different synthesis temperatures. Samples were annealed at 400 °C for 2 h. The morphological, structural and optical properties of the investigated ZnO arrays were characterized using X-Ray diffraction (XRD) spectroscopy, Scanning Electron Microscopy (SEM) and Ultraviolet–Visible Spectroscopy (UV/vis). The wurtzite and hydrophobic ZnO films showed rod arrays morphology. The optical band gaps were obtained between 3.8 and 3.85 eV. The ZnO arrays exhibited a low degradation efficiency because of the increase in Eg value.