CAREER: Plasma Chemical Vapor Deposition of Amorphous Silicon Thin Films near Room Temperature Using Inert Ion Enhanced Processes

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Abstract - Parsons - 9624612 Large area electronic systems, including active matrix liquid crystal displays, image sensors, and photovoltaic cells utilize active semiconducting layers that must currently be formed at temperatures exceeding 300(C. Substrates which make up the device platform are limited, therefore, to materials such as fused silica, glass, or metals which are stable at these temperatures and can withstand temperature cycling. New chemical processes that will allow for high quality semiconducting layers to be formed at lower temperatures will lead to new options for device platform materials, leading to a new generation of light weight and flexible large area electronic devices. When conventional methods to form amorphous silicon thin films are attempted at very low temperature, a porous structure commonly results, leading to significant postdeposition oxidation and a high charge trap state density which limits its use as an active semiconductor. Novel approaches for film synthesis have been identified that result in dense, non-porous materials near room temperature, and some of these materials show a reduction in charge trap density after 'activation' by a low temperature (150(C) anneal. In addition, preliminary results indicate that an ion-enhanced hydrogen desorption process in plasma activated chemical vapor deposition, which has previously not been documented, may be critical for achieving high film density. The objectives of this study include the description and analysis of these plasma activated deposition processes. The results will lead to new low temperature copabilities in silicon thin film materials and devised, and extend understanding of low temperature surface chemistry in plasma activated materials synthesis and plasma/surface interactions. Undergraduate and graduate education in the area of electronic materials will be advanced by projects in: 1) the development of an upper level course in electronic materials; 2) a new electronic materials option in the undergraduate chemical engineering curriculum; and 3) an emphasis on cooperative learning and learning styles in the classroom. These will offer students and opportunity to broaden their education scope, and help prepare them for employment or graduate studies in an area where there is a growing need for engineers.