The road to high performance single walled carbon nanotube thin film transistors: purification, densification, and integration

carbon nanotubes;purification;transfer printing;thin film transistors

Du, Frank

关键词: carbon nanotubes;    purification;    transfer printing;    thin film transistors;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/50468/Frank_Du.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Single walled carbon nanotubes (SWNTs) have garnered substantial interest in the electronic materials research community due to their unparalleled intrinsic electrical properties. In particular, aligned arrays of SWNTs grown via chemical vapor deposition (CVD) on quartz enable device uniformity and wafer scale integration with existing commercial semiconductor processing methods. However, major crucial roadblocks continue to hinder the incorporation of SWNTs in commercial electronics.First, co-existence of metallic and semiconducting SWNTs results in thin film transistors with unacceptably poor switching ratios. Demanding device metrics in high performance and complex integrated electrical devices, sensors, and other applications dictate the necessity of pristine, purely semiconducting arrays of SWNTs. Here we present a simple, robust process that yields pristine arrays of purely semiconducting SWNTs (s-SWNTs) by use of irradiation with an infrared laser. Systematic experimental studies and computational modeling of the thermal physics reveal all essential aspects of this process. We also demonstrate high performance thin film transistors using purified s-SWNTs arrays. Second, low spatial density of SWNTs in aligned arrays grown on quartz limits the current density necessary for high performance modern electronics. We present an advanced, precisely aligned iterative transfer printing process for densification of aligned arrays. This process incorporates new polymeric encapsulation media, resulting in substantially cleaner substrates.Lastly, we describe new results on the advanced development of soft lithography techniques with the ability to transfer print aligned arrays of SWNTs onto alternative substrates after synthesis and processing, thereby completing a direct pathway to achieve complex, high performance, and highly integrated SWNT electronics, sensors, or other devices.