Optical, morphological and mechanical properties of an Al–Al2O3 nanocomposite thin film grown by thermionic vacuum arc

Abstract

An Al–Al2O3 nanocomposite thin film was deposited onto a glass substrate in high vacuum condition using Al2O3 pellets as source material by means of the thermionic vacuum arc technique in just 50s. UV–visible spectrophotometer, optical reflectometer, spectroscopic ellipsometer, XRD, FESEM and AFM were employed to investigate the optical, structural morphological and mechanical properties of the produced film. The film exhibited a high transmittance (above 80%) in the 400–1000nm region. The dispersion of the refractive index was discussed in terms of the single oscillator model. The optical band gap value derived from the Wemple–DiDomenico dispersion relationship was 5.7eV. It was observed that the results of the optical investigations agreed well with Al2O3 thin films. XRD characterization showed that the film contained Al and Al2O3 phases. The FESEM analysis revealed that the film morphology had a dense characteristic. 2D and 3D AFM micrographs indicated a smooth surface with a low value of average roughness. When compared to the mechanical properties of Al2O3 thin films, it was observed that the hardness and Young's modulus reduced due to presence of ductile Al particles.