Electronic Devices on Plastic Substrates

近年来新的应用，如大面积共形显示器，多色有机显示器。容错太字节存储器、大面积太阳能电池、用于生物应用的保形电子传感器等要求有源电子器件生长在塑料膜上。除了有机LED之外，几乎所有的这种器件都使用非晶硅作为活性材料。然而，非晶硅材料具有低载流子迁移率和差的稳定性。因此，在塑料基底上用结晶硅基材料生长薄膜电子器件的能力可以在这些应用中提供更好的性能和更大的稳定性。这样的发展还将允许在聚酰亚胺层上生长c-Si器件，聚酰亚胺层在标准的基于c-Si晶片的器件技术中被广泛用作平坦化绝缘体，从而允许三维器件架构。薄膜晶体器件的发展将是非常有用的有机发光二极管与驱动电路在聚合物基板上的有效集成。这是本提案的目标，以开发高性能的晶体硅基电子器件在塑料基板上。拟议的工作是基于我们最近的成功，在NSF SGER基金，在能够存款高品质的c-Si薄膜聚酰亚胺。并在其中制造概念验证的单晶硅太阳能电池。我们计划进行一项全面的研究项目，以改善薄膜的电子性能，并在thcse薄膜中制造新型TFT器件。该项目包括以下任务：o在一种新型的、控制良好的ECR反应器中，在生长过程中使用H、Cl和F的反应离子束来控制薄膜的结晶度。o使用拉曼、TEM对结构特性进行系统研究。SEM和x射线衍射。o通过DLTS、霍尔测量和缺陷能级的电容谱系统研究电子特性。o研究稳定场氧化物的生长（MOS器件中的栅极绝缘体），并使用电容和电导技术研究氧化物/半导体界面。包括电荷泵浦和电荷注入后的沟道迁移率和稳定性。这一成果依赖于我们在材料生长、材料分析、器件制造以及器件设计和分析方面的经验。有开展这项工作的设施。一个重要的教育组成部分计划，包括研究生和本科生的参与。本科生将从我们正在进行的NSF-REU网站程序绘制。一个重要的少数民族学生的研究经验也计划。女学生，特别是高中一级的女学生也将参加该方案。该计划将导致在这一领域的新课程的开发，从而整合研究和教育。该项目可能对工业产生重大影响。我们计划与美光科技公司进行强有力的合作，该公司预计将提供现金资助，以支持该研究领域的其他研究生。

In recent years. new applications such as large area conformal displays, multi-color organic displays. fault-tolerant terra-byte memories, large area solar cells, conformal electronic sensors for biological applications etc. have demanded that active electronic devices be grown on plastic films. With the exception of organic LED's, almost all such devices use amorphous Si as the active materiaL However, a-Si material suffers from low carricr mobilities, and poor stability. Therefore, the ability to grow thin film electronic devices in cri stalline Si-based materials on plastic substrates may provide both better performance and greater stability in these applications. Such a development would also allow one to grow c-Si devices on polyimide layers, which are widely used as planarizing insulators in standard c-Si wafer-based device technology, and thereby allow three dimensional device architecture. The development of thin film crystalline devices would be very useful for efficient integration of organic LED's with driver circuits on a polymer substrate. It is the objective of this proposal to develop hi2h performance crystalline Si- based electronic devices on plastic substrates.The proposed work is based on our recent success, under a NSF SGER grant, in being able to deposit high quality c-Si films on polyimide. and making proof-of-concept c-Si solar cells in them. We plan a comprehensive research project to improve the electronic properties of the film and to make novel TFT devices in thcse films. The project embraces the following tasks:o Control of crystallinity of the films by using reactive ion beams of H, Cl and F during growth in a novel, well-controlled ECR reactor.o Systematic investigation of structural properties by using Raman, TEM. SEM and x-ray diffraction.o Systematic investigation of electronic properties by using DLTS, Hall measurements and capacitance spectroscopy of defect levels.o Study of growth of stable field-oxides (gate insulators in MOS devices) by controlled plasma-oxidation with F and 0 and study of oxide/semiconductor interfaces, using capacitance and conductance techniques.o Fabrication of horizontal TFT devices.o Measurement of properties of these devices, including channel mobility and stability after charge pumping and charge injection.o Fabrication of novel proottof. concept vertical TFT which may not be affected by grain boundaries.The effort relies on using our past experience in material growth, material analysis, device fabrication and device design and analysis. The facilities exist to carry out this work. A significant educational component is planned, including graduate student and undergraduate student involvement. The undergraduate students will be drawn from our on-going NSF-REU site program. A significant minority student research experience is also planned. Women students, particularly at the high school level, will also participate in the program. The program will lead to development of new courses in this area, thereby integrating research and education. The project has a potentially significant impact on industry. We have planned a strong collaboration with a company, Micron technologies, which is expected to provide a cash grant for supporting additional graduate students in this research area.