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Siliconoxid barrier layers for thin film photovoltaic on flexible metal strips produced by high-rate deposition for large area coatings

: Händel, F.; Morgner, H.; Metzner, C.

Society of Vacuum Coaters -SVC-, Albuquerque/NM:
Society of Vacuum Coaters. 52nd Annual Technical Conference 2009. Proceedings : May 9-14, 2009, Santa Clara, CA USA
Albuquerque: SVC, 2009
ISBN: 978-1-878068-29-3
Society of Vacuum Coaters (Annual Technical Conference) <52, 2009, Santa Clara/Calif.>
Fraunhofer FEP ()
photovoltaic; metal strips; high rate deposition

For thin film photovoltaic applications functional layers are inevitable in terms of electrical insulation and diffusion resistance. The change of material from rigid glass to flexible metal foil as thin film solar cell substrates demands the prevention of diffusion of foreign atoms out of the metal. Furthermore modules with monolithic serial connection need an electrical separation of the cell back contact from the conducting metal substrate. SiOX based layers on metal strips were produced by plasma activated electron beam (EB) technology, hollow cathode arc activated deposition (HAD), plasma polymerization and by a combination of these deposition processes. These methods are distinguished by their in-line capability and dynamic rates of up to 1?m m s-1. Moreover the possibility arises to produce applications with adhesive coatings scaled up to common industrial width and larger dimensions. A big challenge is to provide thermal and chemical stability of the barrier layer during the Copper-Indium/Gallium-Selenium deposition (CIGS) with substrate temperatures of about 600°C. Thus the insulating resistance was determined before and after the CIGS process. Also the breakdown voltage was evaluated for samples without the CIGS layer. The insulating layers are characterized by a breakdown voltage of some hundred volts for layers in the thickness range of about 10?m. Furthermore the efficiency of the barrier diffusion properties was determined by secondary ion mass spectroscopy measurements (SIMS). The positive effect of the barrier layer is apparent from the strong reduction of Fe concentration in the CIGS layer. Additionally structure and layer growth were analyzed with a scanning electron microscope (SEM).