Electronic Devices on Plastic Substrates

在最近几年。大面积共形显示、多色有机显示等新应用。容错千兆字节存储器、大面积太阳能电池、用于生物应用的共形电子传感器等都要求在塑料薄膜上生长有源电子器件。除了有机LED，几乎所有的此类器件都使用非晶硅作为有源材料，但a-Si材料的载流子迁移率低，稳定性差。因此，在塑料衬底上生长晶体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人们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面化绝缘层，从而允许三维器件架构。薄膜晶体器件的开发将非常有助于有机LED与聚合物衬底上的驱动电路的有效集成。这项建议的目标是在塑料衬底上开发高性能的晶态硅基电子器件。建议的工作是基于我们最近在NSF SGER拨款下取得的成功，能够在聚酰亚胺上沉积高质量的c-Si薄膜。并在其中制造概念验证c-Si太阳能电池。我们计划进行一项全面的研究计划，以改善薄膜的电学性质，并在这些薄膜中制造新型的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，利用H、Cl和F的反应离子束控制薄膜的结晶度。o利用拉曼光谱、透射电子显微镜对薄膜的结构性质进行系统的研究。O利用DLTS、Hall测量和电容谱对缺陷能级的电子性质进行系统研究.o用F和O控制等离子体氧化生长稳定的场-氧化物(MOS器件中的栅绝缘体)；o利用电容和电导技术研究氧化物/半导体界面.o制作水平TFT器件.o测量这些器件的性能，包括电荷泵浦和电荷注入后的沟道迁移率和稳定性.o制作新型Prootto.我们致力于利用我们过去在材料生长、材料分析、器件制造以及器件设计和分析方面的经验，开发出不受晶界影响的垂直TFT。有开展这项工作的设施。计划了一个重要的教育组成部分，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现场项目中挑选出来。还计划进行一次重要的少数民族学生研究体验。女学生，特别是高中生，也将参加该计划。该计划将导致在这一领域开发新的课程，从而整合研究和教育。该项目可能会对行业产生重大影响。我们计划与一家名为美光科技的公司进行强有力的合作，预计该公司将提供现金补助，以支持该研究领域的更多研究生。

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.