Imran Kanmaz

In this study, it is aimed to produce triple layer TiO₂/HfO₂/SiO₂ thin films by spin coating method and to minimize optical losses. The characterizations in the study were primarily carried out using XRD, SEM and transmittance and reflectance analyses. The average optical transmittance (400–700 nm) of single layer SiO₂, TiO₂ and HfO₂ film coated silicon substrates were obtained as 93.7%, 82.9% and 86.62%, respectively. The average transmittances for double layer TiO₂/HfO₂ and Triple layer TiO₂/HfO₂/SiO₂ thin films were obtained as 89.41% and 95.44%, respectively. The band gap values of TiO₂, HfO₂ and SiO₂ thin films produced as single layer were calculated as 3.89 eV, 5.62 eV and 5.52 eV, respectively. The average reflectance (380-1100 nm) for single layer films was measured as 13.26%, 10.52% and 17.76% for TiO₂, HfO₂ and SiO₂, respectively, while the triple layer TiO₂/HfO₂/SiO₂ configuration showed a significant decrease in the average reflectance, reaching 7.74% (380–1100 nm), while a minimum reflectance value of 0.3% was obtained at 605 nm.

In this study, CeO₂ thin films were produced using the spin coting method, which is one of the sol–gel methods, in six different molarities. X-ray diffraction (XRD) patterns revealed the characteristic peaks of the films, while Field Emission Scanning Electron Microscopy (FESEM) confirmed their homogeneous structure. Then, radiation shielding parameters like linear absorption coefficient (LAC), mass absorption coefficient (MAC), tent value layer (TVL), mean free path (MFP), and half value layer (HVL) were thoroughly examined. The results showed that increasing molarity had a significant effect on the thickness values of thin films and the absorption parameters were found to improve with increasing molarity. Both LAC and MAC values decrease as the energy level increases, but the increase in CeO₂ molarity leads to a strong increase on these coefficients. The HVL value was also found to be 0.42 cm at the lowest energy of 14.957 keV and to be around 10 cm at the greatest energy of 59.543 keV (0.05 M). When the radiation energy applied to the material was raised from 14.957 keV to 59.543 keV, it was found that the MFP values of 0.05 M CeO₂ thin films grew gradually from 0.61 cm to 14.51 cm. High energy radiation of 59.543 keV and a low density (0.05 M) medium resulted in peak TVL values of 33.423 cm, allowing the radiation to pass through the material with minimal interaction.

This study introduces CeO₂/SiO₂ double-layer film stacks and its antireflection coating effect. Optical properties were analyzed by spectrophotometer measurements; surface morphology and cross-sections were observed by Scanning Electron Microscopy (SEM); elemental distributions and crystallographic properties were determined by Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) measurements. Average reflectance of single-layer 0.3MSiO₂, 0.6MSiO₂, and 0.3MCeO₂ thin films were 30.54%, 20.12%, and 14.23%, respectively. Average reflectance was decreased significantly down to 5.9% by 0.3MCeO₂/0.6MSiO₂ double-layer thin films comparing to those of the results of single-layer films and bare silicon surface reflection (~40%). Antireflective effect of the films on solar cells was estimated by simulation using the measured reflection data. Simulated solar cells indicate that 0.3MCeO₂/0.6MSiO₂ double-layer antireflective coatings are capable to increase the efficiency significantly and conversion efficiency of 21.7% could be achieved.