Investigation of gas sensor applications of metal oxide thin films with thermionic vacuum arc technique

The study sought to examine the electrical and structural characteristics of the samples created by depositing titanium dioxide (TiO₂) metal oxide material using the thermionic vacuum arc method on designated substrates. The substrate materials that were selected were silicon and glass. The study looked at the structural and electrical characteristics as well as the potential use of titanium dioxide metal oxide material as a gas sensor. The material was deposited separately on opaque and semiconducting silicon substrates and transparent and insulating glass substrates. To determine the optical, surface, and electronic properties of the titanium dioxide (TiO₂) thin films grown on glass and silicon substrates, UV-VIS spectroscopy, Filmetrics, Atomic Force Microscopy (AFM), and a Source-Measure Unit (SMU) were employed. Measurements taken by AFM over a 4 μm x 4 μm area at a scanning speed of 4 Hz showed surface roughness values of 3.74 nm and 6.74 nm for TiO₂ grown on glass and silicon, respectively. Silver (Ag) was used as the electrode in the produced samples. To calculate the bandgap energy of the samples, measurements obtained from Filmetrics and UV-VIS spectroscopy were analyzed using the Tauc equation, yielding values of 3.87 eV and 3.66 eV for glass and silicon substrates, respectively. Current-voltage (I-V) and resistance-time measurements, dependent on gas response, were performed using a Keithley 2450 SMU device. These measurements were obtained using the four-wire method. The resulting data demonstrated that TiO₂ thin-film coatings have potential for use as gas sensors.