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Aluminium and tantalum nitride barriers against copper diffusion in solar absorbers

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Original languageEnglish
Pages (from-to)615-623
Number of pages9
JournalSurface Engineering
Issue number8
Publication statusPublished - 2016
Publication typeA1 Journal article-refereed


The thermal stability of magnetron sputtered solar absorber coatings was investigated at temperatures of 200-500 degrees C. Diffusion barriers of aluminium (Al) and tantalum nitride (TaNx) were studied against thermal diffusion of copper substrate atoms. The diffusion barriers studied were experimental DC magnetron sputtered Al and TaNx layers between a copper substrate and an absorber coating. The absorbers were aged by means of heat treatment in air. The influence of diffusion barriers was analysed by optical and microstructural analyses before and after the ageing procedures. Without a barrier coating, copper substrate atoms diffused through the absorber to the surface, which degraded optical selectivity. The diffusion can be prevented or retarded with a dense diffusion barrier layer. The 500-nm-thick Al barrier layer prevented Cu diffusion and retained optical selectivity at 300 degrees C. At higher temperatures, diffusion was observed but the Al barrier retarded the degradation when compared to an absorber without the barrier layer.


  • Solar absorber, Diffusion barrier, Thermal ageing, Copper diffusion, THERMAL-STABILITY, SELECTIVE ABSORBERS, OPTICAL-PROPERTIES, SILICON, CU, FAILURE, TANX, METAL, FILMS, OXIDE

Publication forum classification

Field of science, Statistics Finland