Sol–gel versus sputtering indium tin oxide films as transparent conducting oxide materials

The aim of this paper is the replacing of the expensive sputtering method with the low cost sol–gel one in TCO applications. To this end two sets of indium tin oxide (ITO) thin films are compared and discussed in this paper: one obtained by r.f. sputtering and one by the sol–gel technique and dip-coating. For each of these sets of samples, a series of deposition parameters have been varied in an effort to obtain the most promising optical and electrical properties. Comparative structural, morphological and opto-electrical characterization of sol–gel and sputtered ITO-based films was performed by X-ray diffraction, Scanning electron microscopy, Atomic force microscopy, Spectroellipsometry, UV–VIS Spectroscopy and Hall Effect measurements in order to establish whether the chemical deposition method could lead to thin films with competitive properties as those obtained through the physical method. Comparable, high transmittance (85–90 %) in the VIS–NIR range (250–1050 nm) and carrier concentration values (10²⁰–10²¹ cm⁻³) were obtained between sputtered and sol–gel ITO films. The sputtered ITO film in 75 % N₂, annealed at 500 °C and the sol–gel 0.1 M ITO film with 10 layers deposited on SiO₂/glass exhibit degenerate semiconductor behavior.