Sol–gel derived nanocrystalline titania thin films on silicon

Electrical characteristics of sol–gel derived titanium dioxide (TiO₂) as insulating layers were investigated by making capacitance and leakage current measurements in metal–insulator–semiconductor configurations. The structure was fabricated by depositing 37 nm thick anatase TiO₂ films on p-type silicon (p-Si) substrates. The frequency dispersion of capacitance was attributed to the leaky behaviour of the TiO₂ dielectrics. Using an equivalent circuit, values of the frequency-independent dielectric constant, interfacial surface density and threshold voltage were estimated to be 13, 3 × 10¹⁴ m⁻³ and −0.085 V, respectively. The carrier diffusion was found to be primarily responsible for the diode leakage current at room temperature but the increase in the ideality factor with lowering temperature was believed to be due to fluctuations of barrier height at the TiO₂/p-Si interface.