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Semiconductor manufacture. Worker, wearing protective clothing, inspects a bar of silicon crystal. The bar has been manufactured by a process called crystal pulling. Silicon wafers for use in semiconductor devices must be made from high- quality crystals of precisely controlled orientation and electrical properties. Molten silicon is treated with trace amounts of electrically active elements. A small seed crystal with the desired orientation is then inserted and slowly removed so that the molten silicon solidifies around it. Photographed in Bavaria, Germany. (KEYSTONE/SCIENCE PHOTO LIBRARY/MAXIMILIAN STOCK LTD)