Substrate Dependency of Nucleation Mechanism in the formation of TiO2 Thin Films by Sol-gel Spin-Coating Method

Titanium dioxide (TiO₂) thin films were deposited on glass (Corning 7059) and p-type siliconsubstrates using the sol-gel spin coating technique. The sol-gel solution was prepared by mixinghydrochloric acid (HCl) and deionized water (DIW) in a 1:1 ratio, along with titanium isopropoxide (TIP)and absolute ethyl alcohol (AEA) in a 1:7 ratio. The films were deposited at a fixed spin speed of 1000rpm with varying deposition times (5, 10, 15, 20, 25 and 30 sec). The deposited films were characterizedusing Raman spectroscopy, X-ray diffraction (XRD) and ellipsometry, while microscopic imaging wasused to analyze surface morphology. Raman spectra confirmed the crystalline nature of the TiO₂ films,with the rutile phase exhibiting a peak at approximately 819 nm. XRD results indicated that the maximum[δ] was estimated to be 10.5 nm on glass and 15.13 nm on silicon, as observed. The refractive index (n) ofTiO₂ films on silicon was consistently higher than that on glass across different deposition times.Additionally, the dielectric constant (k) of TiO₂ films on glass indicated better insulating propertiescompared to those on silicon. Thickness measurements revealed that TiO₂ films on silicon were smootherthan those on glass across varying deposition times. Roughness analysis showed that the surface roughness(Ra) of TiO₂ films on glass decreased with increasing deposition time, whereas the roughness of TiO₂films on silicon fluctuated.