Post-deposition annealing influenced structural and electrical properties of Al/TiO2/Si gate capacitors

• TiO2 thin films of 110 nm thick were deposited on p-Si and quartz substrates by DC reactive magnetron sputtering.
• The leakage current density for as-deposited films was 1.2 × 10−6 A/cm2 at a gate bias voltage of 1.5 V.
• The dielectric constant increased from 8 to 34 with the increase in annealing temperature.
• The optical transmittance of the films decreased with the increase in annealing temperature.

Titanium dioxide (TiO2) thin films are deposited on unheated p-Si (100) and quartz substrates by employing DC reactive magnetron sputtering technique. The effect of post-deposition annealing in air at temperatures in the range 673–973 K on the structural, electrical, and dielectric properties of the films was investigated. The chemical composition of the TiO2 films was analyzed with X-ray photoelectron spectroscopy. The surface morphology of the films was studied by atomic force microscope. The optical band gap of the as-deposited film was 3.50 eV, and it increased to 3.55 eV with the increase in annealing temperature to 773 K. The films annealed at higher temperature of 973 K showed the optical band gap of 3.43 eV. Thin film capacitors were fabricated with the MOS configuration of Al/TiO2/p-Si. The leakage current density of the as-deposited films was 1.2 × 10−6 A/cm2, and it decreased to 5.9 × 10−9 A/cm2 with the increase in annealing temperature to 973 K. These films showed high dielectric constant value of 36.