University of Illinois Urbana-Champaign

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

Du, Frank

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Frank_Du.pdf

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https://hdl.handle.net/2142/50468

Description

Title
The road to high performance single walled carbon nanotube thin film transistors: purification, densification, and integration
Author(s)
Du, Frank
Issue Date
2014-09-16
Director of Research (if dissertation) or Advisor (if thesis)
Rogers, John A.
Doctoral Committee Chair(s)
Rogers, John A.
Committee Member(s)
  • Braun, Paul V.
  • Lyding, Joseph W.
  • Dillon, Shen J.
Department of Study
Materials Science & Engineerng
Discipline
Materials Science & Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2014-09-16T17:17:48Z
Keyword(s)
  • carbon nanotubes
  • purification
  • transfer printing
  • thin film transistors
Abstract
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.
Graduation Semester
2014-08
Permalink
http://hdl.handle.net/2142/50468
Copyright and License Information
Copyright 2014 Frank Du

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