Abstract
Dispersions of particles of different shapes and sizes in fluids or solids modify the transport properties of the underlying matrix. A remarkable enhancement in the electrical, thermal and other transport properties of the matrix due to the long aspect ratio dispersions like nanotube/nanowires has been observed my many research groups. This has motivated tremendous research to explore these composites for various macro-electronic and micro-electronic applications in the last decade. Carbon nanotubes (CNTs) network based thin-film transistors (TFTs) promise improved performance for flexible plastic electronics with potential applications in displays, e-paper, e-clothing, bio-chemical sensing, conformal radar, and others. A detailed theoretical and numerical framework is required to understand the functioning of the CNT network transistors and to interpret different experimental observations.
In the present work we develop a computational model based on the classical transport equations to analyze the electro-thermal transport in isotropic 2D nanotube-net (Nanonet) based TFTs. We represent the Nanonet as a simple, two-dimensional, interpenetrating percolating network of metallic and semiconducting nanosticks. The methodology couples the electrical and thermal transport in an efficient and self-consistent manner. We show the effect of electro-thermal coupling on device performance and explore temperature rise as a function of different parameters like channel length (LC), network density, tube-to-substrate thermal conductance (BiS), and tube-to-substrate thermal conductivity ratio.
We also analyze the electrical characteristics of CNTs based organic thin-film-transistors. This technique relies on “doping” the organic host with metallic carbon nanotubes to increase the transconductance (equivalently, reduce effective channel length, Leff). Our analysis reproduces experimental characteristics and explains many trends not understood through the experimental observations. We show that Leff scales as a power-law of CNT-doping density and illustrate the importance of an active subpercolating network of semiconducting-CNTs in an organic host. To explore the viability and potential of this technology, we establish the upper limit of transistor-count for an IC based on this technology as a function of density, on-current and circuit-failure probability.
This work should be important both as a generalization of classical percolation theory to heterogeneous multi-component percolation as well as theory development and optimization of Nanonet transistors for flexible electronics.
Keywords
nanotube macroelectronics
Secondary Subject Category
Engineering, Mechanical (0548)
Date of this Version
October 2007
Department
ECE
Month of Graduation
December
Year of Graduation
2007
Degree
Master of Science in Electrical and Computer Engineering
Head of Graduate Program
M. R. Melloch
Advisor 1 or Chair of Committee
Muhammad A. Alam
Advisor 2
Jayathi Y. Murthy
Committee Member 1
Kaushik Roy