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University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2010 Controlled Assembly And Electronic Transport Studies Of Solution Processed Carbon Nanotube Devices Paul Stokes University of Central Florida Part of the Physics Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Stokes, Paul, "Controlled Assembly And Electronic Transport Studies Of Solution Processed Carbon Nanotube Devices" (2010). Electronic Theses and Dissertations, 2004-2019. 1545. https://stars.library.ucf.edu/etd/1545 CONTROLLED ASSEMBLY AND ELECTRONIC TRANSPORT STUDIES OF SOLUTION PROCESSED CARBON NANOTUBE DEVICES by PAUL STOKES B.S. West Virginia University, 2005 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics in the College of Sciences at the University of Central Florida Orlando, Florida Spring Term 2010 Major Professor: Saiful I. Khondaker © 2010 Paul Stokes ii ABSTRACT Developing techniques for the parallel fabrication of Complementary Metal Oxide Semiconductor (CMOS) compatible single walled carbon nanotube (SWNT) electronic devices is of great importance for nanoelectronic applications. In this thesis, solution processed SWNTs in combination with AC dielectrophoresis (DEP) were utilized to fabricate CMOS compatible SWNT field effect transistors (FETs) and single electron transistors (SETs) with high yield and their detailed electronic transport properties were studied. Solution processing of SWNTs is attractive not only for the high throughput and parallel manufacturing of SWNT devices but also due to the ease of processing at room temperature, and compatibility with various substrates. However, it is generally believed that solution processing introduces defects and can degrade electronic transport properties. The results presented in this dissertation show that devices assembled from stable solutions of SWNT can give rise to high quality FET devices at room temperature and relatively clean SET behavior at low temperature. This is a strong indication that there are no or few intrinsic defects in the SWNTs. The dissertation will also discuss the controlled fabrication of size tunable SWNT SET devices using a novel mechanical template approach which offers a route towards the parallel fabrication of room temperature SET devices. The approach is based on the formation of two tunnel barriers created in a SWNT a distance L apart by bending the SWNT at the edge of a local Al/Al2O3 bottom gate. The local gate tunes individual electrons one by one in the device and defines the size of the quantum dot though its width. By tuning both the back gate and local gate, it is possible to tune the transparency of tunnel barriers and the size of the quantum dot further. Detailed transport spectroscopy of these devices will be presented. iii To my wife and parents iv ACKNOWLEDGMENTS Like most doctorate students the past 5 years for me have been an up and down ride. There have been a number of people around me that have contributed significantly to my success. I would like to first thank my advisor, Dr. Saiful Khondaker. Saiful was the first person to spark my interest in nanoelectronics and never let me say that I can not do something. He spent countless hours sharing his wisdom with me. I have learned so much about science and life in general from him. He is one of the hardest working people I know, and pushed me to strive hard myself. Together we built a successful and competitive lab from almost scratch, a truly priceless experience. He will always be a friend and a mentor to me. I would like to thank my lovely wife, Megan for always encouraging me when I was frustrated or discouraged. She supported me everyday and appreciated the intense focus it takes to obtain a PhD. I could have not done it without her. I am most indebted to my parents. My parents have been the most influential people in my life. Both of them are some of the hardest working people I know. My mother’s job is tougher than any science I have ever done. And my father, the smartest person I know. If there is something that can be fixed, he can find a way to fix it, a quality that I think I acquired from him and greatly appreciate. Support from parents and my sister’s, Kym and Melinda though my entire education has been crucial for my career. I would also like to thank a number of professors at UCF who have helped me though my PhD: Dr. Peale, who first mentored me and taught me how to use a machine shop; Dr. Ishigami for numerous discussions on carbon nanotube and being a second mentor to me; Dr. Mucciolo v for a number of helpful discussions on nanotube quantum dots; Dr. Zhai for insights on chemistry, and Dr. Artem Masunov and Dr. Lee Chow for serving on my committee. Post-docs such as Dr. Jianhua Zou and former student, Harish Raman have also been extremely helpful in teaching me chemistry. I would also like to thank Dr. Ivan Divliansky, Ed Dein, Kevin Casey, and David Bradford for their technical help, the late Paul Alman for help around NSTC, and former and current staff members at NSTC. Finally, I would like to thank all of my previous and current lab members for making my PhD enjoyable. It was a pleasure advising Eliot and Kristy. They are both terrific undergraduate students. I thank Daeha, Biddut, Rakib, Arif, Shashank, Surajit, Tanushri, Yodchay, Firoze, and Liwei for their support, help and scientific insights. vi TABLE OF CONTENTS LIST OF FIGURES ........................................................................................................................ x LIST OF TABLES.....................................................................................................................xviii CHAPTER 1: INTRODUCTION................................................................................................... 1 1.1 Motivation............................................................................................................................. 1 1.2 Organization of this thesis .................................................................................................... 6 References................................................................................................................................... 7 CHAPTER 2: BACKGROUND..................................................................................................... 8 2.1 Historical overview of carbon nanotubes ............................................................................. 8 2.2 Carbon nanotube structure .................................................................................................... 9 2.3 Electronic properties of carbon nanotubes.......................................................................... 10 2.4 Assembly of carbon nanotube devices................................................................................ 12 2.4.1 Find ‘em’ and wire ‘em’ technique.............................................................................. 12 2.4.2 Direct growth techniques ............................................................................................. 13 2.4.3 Post-synthesis techniques............................................................................................. 15 2.4.4 Dielectrophoresis ......................................................................................................... 17 2.5 Carbon nanotube field effect transistors ............................................................................. 22 2.6 Single electron tunneling and coulomb blockade ............................................................... 26 2.6.1 The single electron transistor....................................................................................... 26 2.6.2 Transport though a single electron transistor............................................................... 28 2.6.3 Fabrication of single electron transistors ..................................................................... 31 2.6.4 Nanotube quantum dots ............................................................................................... 32 2.6.5 Scaling towards room temperature operation .............................................................. 34 References................................................................................................................................. 35 CHAPTER 3: DEVICE FABRICATION AND EXPEREMENTAL METHODS...................... 42 3.1 Introduction......................................................................................................................... 42 3.2 Fabrication of electrodes..................................................................................................... 43 3.2.1 Photolithography.......................................................................................................... 43 3.2.1.1 Bi-layer resist recipe ......................................................................................... 43 3.2.1.2 Metallization ..................................................................................................... 44 3.2.1.3 Lift-off..............................................................................................................

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