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

摘要- Parsons - 9624612 大面积电子系统，包括有源矩阵液晶显示器、图像传感器和光伏电池，利用目前必须在超过300 ℃的温度下形成的有源半导体层。 因此，构成器件平台的衬底限于在这些温度下稳定并且能够承受温度循环的材料，例如熔融石英、玻璃或金属。 允许在较低温度下形成高质量半导体层的新化学工艺将为器件平台材料带来新的选择，从而产生新一代重量轻且柔性的大面积电子器件。 当在非常低的温度下尝试形成非晶硅薄膜的常规方法时，通常会产生多孔结构，导致显著的沉积后氧化和高电荷陷阱态密度，这限制了其作为有源半导体的用途。 已经确定了用于膜合成的新方法，其在室温附近产生致密的无孔材料，并且这些材料中的一些在通过低温（150（C）退火的“激活”之后显示出电荷陷阱密度的降低。 此外，初步结果表明，在等离子体激活的化学气相沉积，这是以前没有记录的离子增强的氢解吸过程，可能是实现高膜密度的关键。 本研究的目的包括这些等离子体活化沉积过程的描述和分析。 这些结果将导致硅薄膜材料的新的低温copabilities和设计，并扩展等离子体活化材料合成和等离子体/表面相互作用的低温表面化学的理解。 电子材料领域的本科和研究生教育将通过以下项目推进：1）电子材料高级课程的开发; 2）本科化学工程课程中的新电子材料选项; 3）强调课堂上的合作学习和学习风格。 这些将为学生提供机会，扩大他们的教育范围，并帮助他们为就业或研究生学习做好准备，在这个对工程师的需求不断增长的领域。

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.