Inexpensive fabrication of radiation shielding and hydrophobic hafnium dioxide thin films for electronic, photonic and optoelectronic applications

Metal oxide thin film technology provided solutions for many electronic passive and active devices by forming a nanometer level layer on the desired substrate due to their excellent optical properties, mobility of the carriers, and electrical stability. But the fabrication of these thin films in the nanometer level depends on expensive approaches like chemical vapor deposition (CVD), and physical vapor deposition (PVD). The inexpensive manufacturing of extremely thin films for photonic and optoelectronic applications is always groundbreaking research. This paper presents the fabrication of HfO₂ thin films utilizing a simple sol-gel spin coating process for photonic and optoelectronic applications. X-ray diffraction (XRD) investigations on HfO₂ thin films annealed at 500 ^OC revealed the films’ monoclinic structure. Fourier transform infrared spectroscopy (FTIR) investigations of spin coated HfO₂ thin films confirmed the development of Hf-O functional links at 654 cm^− 1, 997 cm^− 1, and 1226 cm^− 1, respectively. The morphological and elemental analysis using field emission scanning electron microscopy and energy dispersive x-ray spectra revealed the development of tube-like structures on the surface of the films with atomic weight percentages of hafnium and oxygen of around 35.68 and 64.32, respectively. The surface roughness of the HfO₂ films was studied using atomic force microscopy (AFM), which revealed an average roughness of approximately 2.6 nm. The optical property reflectance of hafnium dioxide thin films was investigated using a UV-VIS-NIR spectrophotometer, which revealed 45% reflectance in the near-infrared range with only one layer. Furthermore, to use the fabricated hafnium dioxide thin film for electronic applications, it was subjected to water contact angle analysis (WCA) using the sessile drop technique, and the contact angle was found to be around 110^O, indicating that the film is hydrophobic and can be used as a protective cover on the applied substrates.