Transparent conducting films in the Zn-Sn-O tie line

Abstract

Coatings were obtained on borosilicate glass and fused silica substrates with thicknesses of up to 230 nm from solutions with compositions along the Zn-Sn-O tie line. The preparation of the sols was accomplished by combinatorial chemistry with a robotic sample processor using different Zn-II, Sn-II and Sn-IV salts and alkoxides, as well as salts of different doping agents ( e. g. Sb-V, Ta-V, In-III) dissolved in various solvents and additives. The films were made by spin- coating followed by a thermal treatment in air, inert or reducing atmosphere at temperatures up to 1000°C. Except for a few cases, mixed crystalline phases of ZnO, SnO2 and ZnSnO3 or Zn2SnO4 are usually observed within the range 0.4 < [Zn]/([ Zn] + [ Sn]) < 0.75. Pure Zn2SnO4 and ZnSnO3 coatings exhibit good optical properties with a haze < 0.2% and a transmission in the visible range > 85%. In contrast to literature, results obtained for similar coatings by sputtering and pulsed laser deposition, all the sol - gel coatings showed a high resistivity of rho > 3 &Omega;cm even after a forming gas treatment and/ or doping.