W. Rod Harrell
Associate Professor of Electrical and Computer Engineering
Ph.D. - University of Maryland, College Park
M.S. - University of Kentucky
B.S. - University of Kentucky
Office: 205 Riggs Hall
Office Phone: 864.656.5918
Rod Harrell was born in Lebanon Kentucky. He received the B.S. and M.S. Degrees in Electrical Engineering from the University of KY. After completing the M.S. degree he worked for the National Security Agency (NSA) as a microelectronics research engineer. He was awarded an NSA Graduate Fellowship to attend the University of Maryland at College Park, where he earned the Ph.D. Degree in Electrical Engineering in 1994. His doctoral research was conducted at the Microelectronics Research Laboratory (MRL) of NSA. After completing the Ph.D., he continued working at the MRL until August 1997, when he joined the Department of Electrical and Computer Engineering at Clemson University as an Assistant Professor. Dr. Harrell is a member of IEEE, and has served as a peer reviewer for IEEE Transactions on Electron Devices, Solid-State Electronics, and Applied Physics Letters. He is listed in the 1996-1997 edition of Marquis Who's Who in Science and Engineering.
Professor Harrell's research interests are in the broad areas of electronic materials and devices. Specifically, his research interests include: IV-IV compound semiconductor materials and devices, specifically silicon-carbide; organic polymer-based semiconductor devices; metal contacts to electronic materials; thin dielectrics for MIS devices; modeling of Poole-Frenkel mechanisms in dielectrics and semiconductors; and the electrical characterization of semiconductor materials and devices. Additionally, he is generally interested in expanding the range of electronic applications for elemental and compound silicon, as well as organic polymer-based materials and devices.
Organic Electronics: Polymer-Based Devices
Polymers are materials consisting of long chains of repeating structural units, or monomers, connected by covalent bonds. Most polymers are plastics and are very poor conductors of electricity. However, in recent years a new class of polymer has been developed which does conduct electrical current, and these materials are usually referred to as Inherently Conducting Polymers (ICPs). When and ICP is mixed with a solvent and doped with an protonic acid, the solution can be spun or printed onto a substrate and dried. Depending on the synthesis and doping, layers of ICPs can be deposited with conductivities ranging from insulating to semiconducting to metallic. These materials can be prepared at relatively low cost with a wide range of electronic, optical, and mechanical properties, and thus have wide applications in micro- and nanoelectronics. We are currently investigating the electronic, thermal, and mechanical properties of various ICPs, using different solvents and protonic acid dopants. In addition, we perform research into electronic device applications using ICPs. Devices such as capacitors, diodes, and transistors made with ICPs are a major focus in our lab. These devices have applications in sensors, photonics, flexible microelectronic chips, and solar cells just to name a few. The potential for these materials and devices are really only limited by the imagination.
Polymer/Carbon Nanotube Composites
Carbon Nanotubes (CNT) have generated significant interest in recent years for nanostructure and materials technology. CNTs are known to possess exceptional electronic, mechanical, and thermal properties. Likewise, ICPs have potential applications in nanoelectronics due to their high potential to provide low cost, lightweight, flexible electronic and photonic materials using relatively simple processing methods. Although both CNTs and ICPs have very promising physical properties, there are significant challenges in bringing them to their full potential in practical applications. Combining these two materials to form composites can potentially exploit the strengths of each while overcoming some of the challenges involved in utilizing the individual materials. There are essentially two perspectives with which to view this class of nanocomposites. Either conducting polymers functionalize CNTs, or CNTs effectively dope the polymer. CNTs have been shown to improve the thermal stability, mechanical strength, and electrical conductivity of ICPs. Combining the unique properties of conducting polymers and CNTs into functional nanocomposites offers many opportunities for research into basic materials science as well as technological applications. In our lab we are not only studying the electronic, thermal, and mechanical properties of these nanocomposite materials, but investigating electronic device applications such as supercapacitors, sensors, diodes, and transistors.
Electronics is fundamentally the study of the physics, chemistry, & materials science of charge motion in a semiconductor, gas, or vacuum. Bioelectronics, therefore, is the study of the movement of charges (electrons and/or ions) within biological materials. Our lab has recently become involved with Clemson’s Center for Bioelectronics, Biosensors and Biochips (C3B). This area of research applies many of the ideas and techniques used in our organic and inorganic nanoelectronics work to understand the interface between biological materials and solid state materials such as metals, insulators, and semiconductors. This research has applications in implantable biological sensors and diagnostic biochips for future clinical use.