Study of single-walled carbon nanotubes for applications in transistors, photodetectors, and stretchable electrodes for tactile sensors [electronic resource]
Keywords: Materials Science and Engineering.

Single-walled carbon nanotubes (SWNTs) are tubular carbon-based nanostructures that can be envisioned as graphene rolled up into a seamless cylinder. They are an ideal candidate for use in various electronic and optoelectronic applications due to their unique properties such as high carrier mobility, high light absorption, mechanical flexibility, and solution processability that enable large area, and low cost electronics. Some of the applications include circuits, RFID tags, photodetectors, electronic paper, and robotic systems with skin-like sensing capabilities. To enable these exciting applications, characterization, optimization of device performance, and novel device concepts with properties tailored to specific applications are critical. There are generally two different ways of using SWNTs in electronic devices: 1) as active semiconducting material (in devices like transistors, photodetectors etc.) and 2) as metallic electrodes (as interconnects, electrodes in stretchable tactile sensors etc.). In Chapter I, we will review the recent progress of using SWNTs in both of these applications. Chapter I should equip the reader with a background and understanding of current trends and future outlook of SWNT-based electronics. In Chapter II and Chapter III, we will discuss a novel technique to generate electrical contacts to individual SWNTs, known as dip-pen nanolithography, to characterize their electrical properties. Characterization of electrical properties of individual SWNTs is critical to the understanding of their behavior in large-scale systems. In Chapter II, we will emphasize on the methods and insights to fabricating high quality electrodes with uniform dimensions and functionality. In Chapter III, we will focus on the electrical characterization of individual SWNTs using DPN-fabricated short-channel transistors. Here, we will use our short-channel devices to statistically quantify the percentage of semiconducting versus metallic SWNTs of a solution sorting system, along with critical device parameters such as on-conductance, on/off ratio, and threshold voltage. In Chapter IV, we will move onto discussing large-scale, SWNT film-based transistors. Here, we will introduce a novel technique known as solution shearing to densely align SWNTs over a large area. We will compare aligned SWNT versus randomly oriented SWNTs to elucidate how dense packing and alignment affects the electrical properties of SWNT films. In Chapter V, we will present a hybrid film of SWNT and fullerene as highly sensitive infrared photodetectors. Here, we will discuss how sensitivity can be enhanced using various parameters, and how it can potentially be used in various application such as flexible infrared imaging devices. Finally, in Chapter VI, we will present a stretchable energy harvesting electronic skin device, where SWNTs were used as stretchable electrodes. Here, we will discuss the key concepts in enhancing pressure sensitivity, how to differentiate between different tactile information, and how energy can efficiently be harvested to generate electrical power. Each chapter will conclude with a brief summary, and will discuss the challenges that need to be met to fully realize the potential of SWNTs. This thesis should not only provide new insights to enhancing device performance, but should also excite the reader on the promising outlook of SWNT-based electronics, and motivate them to pursue them.