Indium tin oxide (ITO) | Optical characterization of thin films

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Indium tin oxide (ITO) films are widely used as transparent electrodes, transparent heating elements, coating electrodes in optoelectronic devices (flat panel displays), electroluminescent devices, electrochromic devices, liquid crystal displays, and so on. ITO films are used extensively because of their high transparency in the visible region and excellent electrical conductance. Among the transparent conductive oxides (TCOs), ITO is one of the most frequently used materials because of these unique characteristics.

Various deposition and coating methods have been used to produce ITO thin films, and these differences strongly affect the optical and electrical properties of ITO thin films. We produce ITO materials that are particularly suited to thermal evaporation using resistive heating or electron beam irradiation.

Conditions that influence the transparency and resistance of ITO thin films

  • Film thickness: The thicker the film, the lower the electric resistivity and transparency in the VIS region.
  • Substrate temperature for physical vapor deposition coating: When not using ion bombardment, a temperature of approximately 300 degree will produce low resistivity and high transparency. Annealing is also known to improving these two parameters.
  • Oxygen pressure: The greater the pressure, the higher the transparency and resistivity.
  • Surface roughness: The smoother the surface, the lower the resistivity and higher the transparency.
  • Inclusion ratio of Sn: Too much or too little doping with Sn will lower the resistivity.
  • Coating method: Elector beam deposition, CVD, magnetron sputtering, ion plating, reactive evaporation deposition, sol-gel method, etc. Each method produces different electrical and optical properties.