Fabrication and characterization of ITO thin films deposited by excimer laser evaporation

We report the fabrication of tin-doped indium oxide (ITO) thin films by pulsed laser evaporation (PLD) without post-annealing treatment. The electrical, optical and structural properties of these films have been accurately investigated. We show that this growth method gives good quality ITO layers with high transparency (higher than 80% in the visible spectrum) and low electrical resistivity (in the order of 3 x 10(-4) Omega cm). Considering the free electrons contribution in the near-infrared region, we determine the plasma frequency, the relaxation time, the high frequency dielectrical constant and the optical effective mass of the electrons in conduction band. Therefore, we establish the variation of the ITO optical complex refractive index in the wavelength range between 0.3 and 1.5 mu m. Moreover, in applications on an InP solar cell, Auger profilometry shows that PLD preserves the substrate surface and, therefore, PLD is a technologically simple method providing good ITO ohmic transparent contact.