Deposition of ITO films on SiO2 substrates

Pulsed ablation deposition (PAD) has been used to deposit indium tin oxide (ITO) films on SiO2 substrates at room temperature using an ArF excimer laser. High optical transmission above 88% occurred in the visible region, the refractive index (2.0 at 540 nm) was observed to be very close to the one of the bulk target; the extinction coefficient was low and almost constant (6 × 10−3) through the visible range. An energy gap of about 3.6 eV has been calculated for the deposited films. The film thickness profilometer (FTP) and simulations using a computer code (refractor) give approximately the same result for the film thickness (≈370 nm). The electrical resistivity was as low as 4 × 10−6 Ωm. From the atomic force microscopy (AFM) observations, the films had a rough surface with average roughness ≈20 nm. Pores were observed with a density of ∼150 pores/μm2 and average size of 250 nm. Therefore films exhibited large surface area, which suggest applications in dye solar cells (DSC).