Indium Tin Oxide conductivity vs typical (Semi/)conductors - Page 1
Forum section: electronics / general

author: mclute0
author_rank: Regular Contributor
timestamp: June 02, 2022, 06:06:52 am
content: Material problems are my weakness.The bold parts are the question I am posing, and the rest is just superfluous.I was looking into a project that maybe uses Indium Tin Oxide and I was trying to generally estimate conductivity as is measured in the "Big Table of Electrical Resistivity and Conductivity" that is available from numerous sources, but Indium Tin Oxide is missing from the all the tables I have seen. I am not really sure why except that it a mixture not an element and so there is no standard mixture to measure.The MIT.EDU materials database for ITOhttps://www.mit.edu/~6.777/matprops/ito.htmshows references toElectrical conductivity(“standard” sputtered) @~10^4 S/cm(epi, 5.7wt% SnO2) @~1.3 x 10^4 S/cmnow most of the Big Tables list it at S/m so the sputtered should be 10^6 S/m, correct? That is similar to Mercury?Are these numbers correct?It's been a long time since I looked at this in school in general and we didn't really have much interest in ITO back it the dark ages of the CRT.The fact that the units are different makes me doubt if the measurements are valid for comparison, but my mind tells me the measurements should standard.I think I just need to order some indium and SnO2 and roll my own and do the tests myself, but that is a budget hit. I think I will need to some Cr too, and that will just make it a chemistry mess for me.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 02, 2022, 09:18:48 am
content: The conversion of units is right. The number for the conductivity looks plausible, though chances are that this is for a composition optimized for good conductivity and with careful control of composition / structure. So a first try film will likely be somewhat off and less conductive.Mercury in the liquid form is less conductive than the more normal crystalline metalls. Platinum as a pure metal with already relatively poor conductivity has 10 times the conductivity.The alternative property to measure would be the film resistance, including the effect of the thickness. That would be a resistance for a square part of film as long as wide and thus no length unit included.The composition is a mixed oxide of indium and tin. So more like indium oxide plus a little tin oxide.As it is relatively common, one may get ready made sputter targets of the right composition. One may still need oxygen in the gas and may as well start with a metallic InSn alloy and get all the oxygen from the gas.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 02, 2022, 12:11:04 pm
content: I recall there's also a way to coat using mixed chlorides, which probably leaves a lot of chloride impurity (doping?) in the deposit too. Whether that's of commercial interest, dunno...And yeah, indeed films can have different behaviors from bulk materials; I don't know if this is true of ITO, or most amorphous or poly materials you'd deposit on glass, but something to think about in any case.Why the curiosity, are you updating these data or something? Haven't found anything in literature sources? Or, looking for something more primary (direct experimental)? Or just not sure about the veracity of the given numbers?Tim

author: mclute0
author_rank: Regular Contributor
timestamp: June 02, 2022, 05:36:02 pm
content: Without giving away the farm, I'm looking at 'alternative' deposition techniques that rely on some of the unique optoelectrical properties of TIO, 'IF' the material can meet the specification. I would call more of a substrate or multi-layer film than simply a film application. No vacuum is needed and no gas deposition, meaning cost will be lower and therefore making ITO a possibility for the application despite the cost of Indium.Given the numbers I am finding it may need some doping to increase charge carries like maybe NiO2 or Zi02 or both. In the application conductivity is more critical than optical permittivity but optical permittivity is critical to the deposition process.Most of the information I am finding are from research papers on TIO associated with emphasis on optical permittivity. This application is novel and would not correspond directly to any paper I have looked at.It looks to me that direct experimental, à la 'Edison Works', research is the solution du jour. I am trying to hammer out what that might look like given that even the US NIST doesn't seem to list ITO specifically, let alone provide available samples.The prices I have seen for ITO range from $1,000 USD/kg at mainstream outlets to $50 USD/kg from China. My main aim at this point is budgeting vs realistic goals.