Effects of thermal treatment on the electrical behavior of titanium dioxide thin-films

Abstract

Electrochemical biosensors made of titanium dioxide have generated significant interest due to their high sensitivity and selectivity for the detection of a variety of diseases. This study focuses on the impact of thermal treatment in an oxygen environment on the electrical properties of titanium dioxide thin films deposited on silicon substrates using pulsed laser deposition; the films were subjected to temperatures of $$\varvec{100\,\,^{\circ }C}$$ 100 ∘ C , $$\varvec{400\,\,^{\circ }C}$$ 400 ∘ C , and $$\varvec{600\,\,^{\circ }C}$$ 600 ∘ C . The primary objective was to explore how thermal processing influences the electrical characteristics of the thin films, with the goal of enhancing their capacitance and thereby improving the performance of sensors developed by functionalizing these films; X-ray photoelectron spectroscopy revealed the presence of Ti$$^{4+}$$ 4 + , Ti$$^{3+}$$ 3 + and TiO$$_x$$ x species in the untreated thin film and in the heat-treated films, with an increase in TiO$$_x$$ x species observed after oxygen heat treatment. Atomic force microscopy demonstrated a decrease in the surface homogeneity of the films at elevated treatment temperatures, which corresponded to a reduction in capacitive behavior; this was further corroborated by Nyquist plots derived from electrochemical capacitance spectroscopy (ECS). The study found that the electrochemical capacitance at lower frequencies decreased significantly from $$\varvec{1.02\,\, \mu Fcm^{-2}}$$ 1.02 μ F c m - 2 to $$\varvec{0.25\,\, \mu Fcm^{-2}}$$ 0.25 μ F c m - 2 when the treatment temperature was increased to $$\varvec{600\,\,^{\circ }C}$$ 600 ∘ C