Structural and gas sensing properties of NiO thin films deposited by a novel spin coating technique

This study presents the development and application of a novel sol-gel spin coating technique for the deposition of nickel oxide (NiO) thin films on glass substrates. The newly designed spin coating device operates without the need for a vacuum, providing a cost-effective alternative to traditional methods. NiO thin films were prepared using a sol-gel process, with various thicknesses and rotation speeds tested to idealize film quality. Structural and morphological analyses were conducted using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM), revealing that the 6-layer sample coated at 3000 rpm exhibited the best crystallization and surface homogeneity. Gas sensor tests were performed to evaluate the sensitivity of the NiO thin films to ethanol, NO2, and H2 gases. The results showed that the sensor responded stably and reproducibly over multiple gas exposure cycles. It also demonstrated the potential for reliable gas detection applications.