The effects of surface roughness and nanostructure on the properties of indium tin oxide (ITO) designated for novel optoelectronic devices fabrication

Indium tin oxide (ITO) was deposited on a glass (Soda Lime glass) by RF sputtering system at different sputtering gas (Argon/oxygen 90/10%) pressures (20–34 mTorr) at room temperature. The sputtering rate was depended on sputtering gas pressure. The optimum sputtering gas pressure of 27 mTorr provides homogenous and most favorable rate of deposition. The samples at different thicknesses (168, 300, 400, 425, 475, 500 and 630 nm) were deposited on substrate and were annealed at 350, 400 and 450 °C to evaluate annealing process effects on the involved parameters. Structures, transparency, electrical conductivity and surface roughness of the films were characterized before and after annealing process. Surface properties were measured by scanning probe microscopy (SPM) in contact atomic force mode and the effect of thermal annealing on roughness of the surface and on the structure of deposited film was investigated. The films will exhibit considerable ratio of the optical transmittance to the electrical conductivity. A criterion factor, Q, is defined as the ratio of the normalized average transmittance to normalized resistivity. In addition to intrinsic parameters of ITO, Q severely depends on surface roughness.