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The Coming of Materials Science p9

Các chuyên ngành cơ bản của cơ khí bao gồm: động học, tĩnh học, sức bền vật liệu, truyền nhiệt, động lực dòng chảy, cơ học vật rắn, điều khiển học, khí động học, thủy lực, chuyển động học và các ứng dụng nhiệt động lực học. Các kỹ sư cơ khí cũng đòi hỏi phải có kiến thức và năng lực áp dụng những khái niệm trong môi trường kỹ thuật điện và hóa học. Với một mức độ nhỏ, cơ khí còn trở thành kỹ thuật phân tử - một mục tiêu viễn cảnh của nó là tạo. | 260 The Coming of Materials Science retrospect by Herman 1984 . Bell Labs also had some gate-keepers physicists with encyclopedic solid-state knowledge who could direct researchers in promising new directions the prince among these was Conyers Herring characterised by Herman as a virtual encyclopedia of solid-state knowledge . Herring not long ago Herring 1991 wrote an encyclopedia entry on Solid State Physics . an almost but not quite impossible task. However physicists alone could never have produced a reliable mass-producable transistor. We have seen that in the run-up to the events of 1947 Scaff and Theuerer had identified p- and n-regions and performed the delicate chemical analyses that enabled their nature to be identified. There was much more to come. The original transistor was successfully made with a slice of germanium cut out of a polycrystal and early pressure to try single crystals was rebuffed by management. One Bell Labs chemist Gordon Teal a natural loner pursued his obsession with single crystals in secret until at last he was given modest backing by his manager eventually the preferred method of crystal growth came to be that based on Czochralski s method Section 4.2.1 . It soon became clear that for both germanium and silicon this was the essential way forward especially because intercrystalline boundaries proved to be electrically active . It also became clear that dislocations were likewise electrically active and interfered with transistor action and after a while it transpired that the best way of removing dislocations was by carefully controlled single crystal growth to simplify the geometry of the crystal was so arranged that dislocations initially present grew out laterally leaving a crystal with fewer than 100 dislocation lines per square centimetre contrasted with a million times that number in ordinary material. This was the achievement of Dash 1958 1959 whom we have already met in relation to Figure 3.14 an early confirmation of the .