E!10527 New CERamic sputtering targets manufactured by SPS using tailored powders for TCO COATing deposition

A large number of electronic devices such as solar cells and touchscreens rely on a key component: a display that is both transparent and able to conduct electrical charge. Traditionally, the most commonly used transparent conducting materials are doped metal oxides (TCO), which are only transparent when coated very thinly on a device. While this is convenient in terms of saving weight and space on small objects, transparent conducting films are challenging to deposit on larger products including solar cells and windscreens, especially for achieving sufficient quality. Films are traditionally deposited by sputtering, a process whereby particles are ejected from a solid target material to deposit on the product, the quality of the film being directly related to the quality of the solid target. Conventional TCO sputtering targets are prone to defect formation, inducing lack of reproducibility during deposition, deterioration of film properties and reduction of sputtering process efficiency. In this EUROSTARS project CerCoat, four European SMEs are developing innovative and better performing transparent conducting films using high quality solid targets from optimized raw materials, while reducing productions costs for solar cell and locomotive heated windscreen applications. The CerCoat project is benefiting from the expertise of highly qualified partners covering the whole value chain, including raw material (powder) producer (Cerpotech, Norway), sputtering target manufacturer (Nanoker, Spain) and end-users of sputtering targets (Midsummer, Sweden and Arino Duglass, Spain). CerCoat has a multiple market approach where each partner will commercialize its own optimized product(s) at the end of the project.

The participation in CERCOAT entailed several outcomes for its partners. The most important outcome for Cerpotech AS was gain of significant technological expertise, e.g. development of new products and protocols, addition of a new element into company portfolio and broad knowledge in powder production upscaling. Another important outcome is developing and consolidation of business relationship and social network between the partners, which may lead to future collaborations. CERCOAT results showed that transparent conducting oxides (In,Sn)O3 (ITO) and (Al,Zn)O3 (AZO) have similar performance in solar cell application. Being widely used in solar cells, ITO is an expensive oxide containing indium, which is in list of critical raw materials of EU. An opportunity to replace ITO with AZO has strong commercial benefits such as lower cost and use of available non-critical materials. Solar cells with AZO will have lower price and be more available, which is in direct interest of the society.

The development of sputtering targets characterized by high density, uniform distribution and high electrical conductivity to prevent nodule formation is aimed at CerCoat. New target features will be tailored by fine-tuning of raw powder properties and Spark Plasma Sintering (SPS) application for target manufacturing. Accordingly, CerCoat first results are: -High purity nanostructured ITO/AZO complex powders produced by spray pyrolysis designed for target manufacturing by SPS (CER). -Dense, uniform and nodule-free industrial size ITO/AZO sputtering targets manufactured by SPS that will lead to optimize ITO/AZO film deposition at higher sputtering rates. - An improved performance/cost ratio for the end users of sputtering targets. The second objective of CerCoat is the development of high quality TCO (ITO and AZO) films by magnetron sputtering. Besides the improvement fostered by new sputtering target utilization, an in-deep optimization of sputtering process parameters will be accomplished to tailor new TCO film properties. New ITO/AZO films will be particularly designed and incorporated in CIGS solar cells and locomotive windscreens for the development of new products within photovoltaic and railway industry: -CIGS solar cells with higher power conversion efficiency due to better-performing TCO layer as front contact electrode. -New locomotive heated windscreens with better optical properties and higher heating power capacity based on TCO layer.