Structural and dielectric characteristic of povidone–silica nanocomposite films on the Si (n) substrate

Abstract

The effects of annealing temperatures at 150, 200 and 240 °C were investigated on the povidone–silica nanocomposite film as a gate dielectric. The thermal gravimetric (TGA) and differential thermal (DTA) analyses showed that the decomposition rate of the nanocomposite increased from around 220 °C. The formation of hydrogen and covalent bonds between the elements of nanocomposite was proved via Fourier transform infrared spectroscopy (FTIR). All the films had low root mean square (0.047–0.12 nm) and leakage current densities (1.32 × 10⁻⁵–3.95 × 10⁻⁸ A/cm² at 15 V). The results of deconvoluted X-ray photoelectron spectroscopy (XPS) spectra of the O_1s orbital indicated that the Si–OH hydrogen bonds dominating the film were not annealed (55.9%). The Si–OH hydrogen bonds decreased (18%) and the Si–O–Si covalent bonds became dominant (80.36%) in the film annealed at 150 °C. The percentage of Si–O–Si bonds decreased by further increasing the temperature (200 °C) and these bonds disappeared in the film annealed at 240 °C. A peak also appeared at the binding energy which is about 1 eV less than that of the Si–O–Si bonds in the films annealed at 200 and 240 °C. The capacitance and leakage current density of fabricated FETs based on nanocomposite dielectric film annealed at 150 and 200 °C decreased. The degradation of cross-linked structure in the dielectric film annealed at 240 °C and the presence of polar Si–OH groups in the nanocomposite dielectric film which was not annealed increased the capacitance and leakage current densities.