Carbon nanotube nanoelectronics and macroelectronics

In this dissertaion, I discuss the applications of carbon nanotubes in digital integrated circuits, display electronics, and radio-frequency electronics. Despite the fact that researchers have previously demonstrated excellent field-effect transistors and integrated circuits using an individual single-walled carbon nanotube, the real challenge is to integrate those devices, minimize the device-to-device performance variation, and to make the fabrication process scalable and compatible with industry standards. To overcome these challenges, instead of using individual carbon nanotube for electronic devices, developing assembly techniques that are capable of providing thin films of highly orderd and uniformly distributed carbon nanotubes is indispensable ❧ ❧ With demonstrating scalable, practical, and high performance carbon nanotube electronics as the major objective of my PhD research, I have developed two material platforms, both of which are capable of providing high-performance nanotube transistors at complete wafer-scale. The two material platforms are horizontally aligned carbon nanotubes and thin-films of preseparated high purity semiconducting carbon nanotubes. Besides scalable material platforms, many other essential technology components, including metallic nanotube removal, increasing nanotube density, and methods to obtain air-stable n-type nanotube transistors have also been demonstrated. On the basis of the above achievements, I have further demonstrated various kinds of electronic applications including integrated circuits, display electronics, and radio-frequency electronics. ❧ ❧ The dissertation is structured as follows. First, chapter 1 gives a brief introduction to the electronic properties of carbon nanotubes, which serves as the knowledge background for the following chapters of the dissertation. In chapters 2, 3, and 4, the works related to horizontally aligned carbon nanotubes grown using chemical vapor deposition are presented. The topics include wafer-scale processing of aligned carbon nanotube electronics, improving nanotube density for better device performance, and using metal contact engineering for air-stable n-type nanotube transistors and CMOS integrated circuits. Chapters 5, 6, and 7 discuss the work related to separated nanotube thin-films, where techniques for separated nanotube thin-film assembly, fabrication of high-performance separated nanotube thin-film transistors, and applications in integrated circuits, display electronics, and radio-frequency electronics are explored. Finally, a brief summary is drawn, and some future research directions are proposed in Chapter 8. ❧ ❧ This dissertation, through experimental demonstration, proofs the potential and feasibility of using carbon nanotubes for future beyond-silicon nanoelectronics and macroelectronics. ❧

本论文探讨了碳纳米管在数字集成电路、显示电子学以及射频电子学领域的应用。尽管此前研究者已利用单根单壁碳纳米管（single-walled carbon nanotube）制备出性能优异的场效应晶体管（field-effect transistor）与集成电路，但真正的挑战在于如何实现此类器件的规模化集成、抑制器件间的性能波动，同时使制备工艺具备可扩展性，并与行业标准工艺兼容。为克服上述挑战，相较于仅使用单根碳纳米管制备电子器件，开发能够制备高度有序、均匀分布碳纳米管薄膜的组装技术不可或缺。❧ ❧
本博士研究以实现可规模化、实用化且高性能的碳纳米管电子学为核心目标，开发了两种材料平台，二者均可在完整晶圆尺度上制备高性能碳纳米管晶体管。这两种材料平台分别为水平取向碳纳米管，以及经预分离的高纯度半导体碳纳米管薄膜。除可规模化的材料平台外，本研究还实现了多项关键技术突破，包括金属碳纳米管去除工艺、提升碳纳米管密度的方法，以及制备空气稳定n型碳纳米管晶体管的技术方案。基于上述研究成果，本研究进一步展示了碳纳米管在集成电路、显示电子学与射频电子学领域的各类电子应用。❧ ❧
本论文结构如下：第一章为碳纳米管的电子学特性简介，作为后续章节的知识背景。第二、三、四章阐述基于化学气相沉积（chemical vapor deposition，CVD）生长的水平取向碳纳米管的相关研究工作，内容涵盖取向碳纳米管电子学的晶圆尺度制备工艺、提升碳纳米管密度以优化器件性能，以及利用金属接触工程制备空气稳定n型碳纳米管晶体管与互补金属氧化物半导体（CMOS，Complementary Metal-Oxide Semiconductor）集成电路。第五、六、七章围绕经分离的碳纳米管薄膜展开研究，内容包括分离碳纳米管薄膜的组装技术、高性能分离碳纳米管薄膜晶体管的制备，以及其在集成电路、显示电子学与射频电子学领域的应用。第八章为全文总结，并对未来的研究方向进行展望。❧ ❧
本论文通过实验验证，证明了碳纳米管应用于未来后硅时代纳米电子学与宏电子学的潜力与可行性。