From Applied Optics Wiki
ITO = Indium Tin Oxide
At optical frequencies this behaves as a hard dielectric with refractive index n~2 k~0.01.
At lower than optical freqeuncies it behaves as a conductor.
Thus is can be use to provide an optically transparent wire.
It is useful as a dielectric that can be deposited in the sputterer (since it is also a conductor it doesn't produce space-charge problems and deposits quite well).
We have an ITO sputterer target.
n=2.30, k=0.02 @ 400nm n=1.86, k=0.01 @ 780nm