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2009
Conference Paper
Titel
Reactive magnetron sputtering of ZnO:Al
Titel Supplements
A status report
Abstract
Transparent and conductive ZnO:Al films to be applied as transparent electrodes and window layers in thin film solar cells have received strong interest in the last few years. This material competes against SnO2:F by AP-CVD or LP-CVD and against ZnO:B by LP-CVD. For display application and OLED lighting, on the other hand, ZnO:Al competes against ITO by magnetron sputtering. The state of the art for industrial manufacturing of ZnO:Al films is ceramic target sputtering using sintered target materials, either from planar or rotatable targets since this technique allows for acceptable process stability and cost level at present time [1]. The reactive magnetron sputtering of ZnO:Al, on the other hand, has not achieved industrial relevance for mass production up to now due to the severe demands on closed loop control. This hindered the integration in processing lines for mass production in spite the fact that superior film properties result from reactive sputtering in terms of low absorption, high conductivity and proper light scattering [2]. Furthermore, a substantial decrease of costs can be expected when cost effective metallic Zn:Al targets are used instead of ceramic ZnO:Al2O3 compounds. This paper gives a report on the status of reactive MF magnetron sputtering using an in-line coater for 60 x 100 cm2 substrates at Fraunhofer IST [3]. The paper reports on the performance of ZnO:Al coatings and thin film solar cells and OLEDs utilizing a variety of ZnO:Al films and also on our estimations on the production readiness and cost structure of the reactive ZnO:Al process.