ITO basics

The following figure from literature explain some physics about Indium Tin Oxide (ITO).

The transmission and reflection spectra of ITO. Source: J. Appl. Phys. 60 (1986) R123–R159 and Solar Energy Materials & Solar Cells 91 (2007) 1529–1598

From the above, there are several observations:

  • With more free electrons (doping), energy gap widening is observed, as shown in the region of 300nm in transmission spectra due to Moss-Bursting effect
  • Absorption in visible range due to Urbach tail.
  • Plasmon frequency shifts to shorter wavelength with higher doping. Charge carrier density is in the range of 1E20 to 3E21 cm^-3.
  • Absorption in 20-30um due to phonon absorption. It gradually decreases with higher doping (higher density of charge carriers).

The following Figure summarize the above processes.

Source: J. Appl. Phys. 60 (1986) R123–R159 and Solar Energy Materials & Solar Cells 91 (2007) 1529–1598