Optical Filters 2013 - SCHOTT North America

40Transparent conducting oxide coating (TCO)Spectral range 400 – 5000 nmA transparent conducting coating (TCO) ensures both electricalconductivity and optically transparency. SCHOTT usesITO (indium-tin-oxide) for this purpose.Transparent conductive oxides (TCO) combine transparency in the visiblespectrum, infrared reflectivity and electrical conductivity. IndiumTin Oxide (In2O3:Sn) is the most common.Available article variantsITO single layerITO with AR coatingITO with AR coating and flexibleconnectorsstructured ITO for touch screensOptical sheet resistance can beadapted:Typical sheet resistances/tolerancesReflectance ρReflection if AR-coating is appliedon top of ITO:7 – 5000 Ω/square10+/–4 Ω/square100+/–10 Ω/square300+/–30 Ω/square450 – 650 nm < 1 % averageother ranges on requestOther propertiesHumidity resistance MIL-Std-810C, method 507,proc. 1 : 10 cyclesOperating temperatureNotesPreferred dimensions [mm]External dimensionsUsable areaThicknessup to 200°C for several hoursFlexible connectors can be appliedby conductive epoxyup to 590 x 730 mm (sputtering)up to 150 x 150 mm (EB)upon requestupon requestOther dimensions on requestSheet resistance (Rs) is specified for transparent conductive thin films.The spectral transmission/reflection and electrical conductivity dependon TCO-material and coating thickness.ResistivityRs =[Ω/square] no units of area!filmthicknessResistivity ρ is a property of bulk material – sheet resistance is a propertyof thin films for example: ρ = 3 x 10 –4 Ω cm, film thickness300 nm, then Rs = 10 Ω/squareIf a voltage is applied to electrodes on opposites edges of the film,the resistance Re is given by the length L and the distance D of theelectrodes and the sheet resistance:Transmittance, reflectance [%]100908070605040302010ITOLexample: Rs = 10 Ω/sq and L = 5 x DR e = 10 Ω/sq.x D = 2 ΩLD0300 500 700 900 1100 1300 1500 1700 1900Wavelength [nm]Lexample: Rs = 10 Ω/sq and L = D/5DR e = 10 Ω/sq.x D = 50 ΩLITO(8W/square)+ARITO(8W/square)ITO(8W/square) reflectionITO(20W/square)+AR/AR on backside