from the conferences organized by TANGER Ltd. provisional website
In this contribution, the deposition of tin oxide thin films and the resulting layer properties are investigated. An atmospheric pressure PECVD process using a non-thermal plasma jet was applied, creating the coatings on silicon and glass slides. For a highly reactive oxygen atmosphere, the plasma process was driven with air as working gas. The precursor substance tetra-n-butyltin was provided as an aerosol towards the active plasma zone and is further converted to form the ~100 nm thin layers. Structural, electrical and gas sensing properties were determined of the undoped SnOx layers, deposited at substrate temperatures between 20°C and 500°C.With increasing substrate temperature a decrease in film thickness and roughness of the films could be observed. In general, the films consists of a dense part near the substrate surface and a more porous structure on top. At 300 °C the lowest electrical resistivity with about 7.2 × 10-2 Ωcm occurs in 4-point probe measurements. Experiments for the gas sensing characteristics revealed an electrical response to different atmospheres (water vapour, aqueous ammonia solution) already at elevated measuring temperatures of 150°C. Ammonia concentrations until 25% were tested. The thin films are showing distinct properties in gas selectivity between the changing atmospheres, gas sensitivity during ammonia interaction as well as recurring reversibility after a surface recovery step with pressurized air. So, tin oxide coatings created by atmospheric pressure PECVD are showing already in its undoped state and without further layer post-treatments high application potential.Keywords: Atmospheric pressure PECVD, plasma jet, tin oxide, transparent conductive oxide (TCO), gas sensor
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