Structural, electronic, and optical properties of ITO thin films prepared at room temperature by pulsed laser deposition

Abstract

In this work, indium tin oxide (ITO) thin films have been prepared by pulsed laser deposition (PLD) on quartz and silicon substrates at room temperature, starting from an ITO target with a Sn/In concentration ratio of 0.18. Structural, optical, and electronic properties of these films have been analyzed by means of X-ray photoemission and optical spectroscopy. By the analysis of the X-ray photoemission spectroscopy spectra in the In 3d5/2, Sn 3d5/2, and O 1s binding energy regions, carried out both for films and target, evidence of structural changes after the ablation process was found. It was deduced that the deposited films have an Sn/In ratio equal to 0.10, and are characterized by a predominantly amorphous structure. The optical properties in the visible and the near ultraviolet regions have been deduced by near normal incidence optical reflectivity and absorption measurements. A value of 3.7 eV for the optical band gap and an average refraction index of about 3.0 in the visible photon energy range have been obtained, in agreement with the results of other authors.