Characterization of Titanium Dioxide Thin Films Grown on Glass Substrate by Gasified-Thermal-Carrier-Assisted Evaporation Technique: Impact of Deposition Time

Abstract

In this study, a gasified thermal carrier assisted vapor deposition technique has been used to deposit titanium dioxides thin films of 90, 270, and 480 nm, thicknesses on glass substrates at growth times of 1, 2, and, 3 hours respectively. Varied nondestructive techniques were employed to investigate the impacts of deposition time on the structural, optical, and electrical properties of the TiO2 thin films. X-ray diffraction (XRD) showed that crystals of a polycrystalline nature were preferentially oriented along the (101) direction. The analysis of the chemical composition of the films by energy-dispersive X-ray (EDX) spectroscopy demonstrated very pure TiO2 thin films that were free of contamination and impurities. The SEM images indicated that the TiO2 thin films were cluster forms, with increasing sizes of with the growth times of 1, 2, and, 3 hours, and these times produced thicknesses of 90, 270, and 480 nm, respectively. The study of the optical properties using ultraviolet-visible (UV-Vis) spectroscopy revealed a thickness-inverse relationship between the films’ optical transmittance levels (from 92% to 78%) and their corresponding energy bandgaps. The electrical properties of the TiO2 films were analyzed via a Hall effect measurement system. The electrical resistivity levels of the films were highly correlated with the thicknesses of the films. The lowest value of electrical resistivity for the highest thinness was 55×103Ω· cm. The films showed high densities of carriers, with concentrations of 85×1012 to 35×1013 N (cm−3), and sufficiently low shift resistance levels. According to the obtained results, three hours, which led to the growth of a 270 nm thickness, could be considered as the ideal deposition time for TiO2 thin films for solar cell applications.