Limits of Performance Gain of Aligned CNT Over Randomized Network: Theoretical Predictions and Experimental Validation

• Published in: IEEE electron device letters Vol. 28; no. 7; pp. 593 - 595
• Main Authors: Pimparkar, N., Kocabas, C., Seong Jun Kang, Rogers, J., Alam, M.A.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.07.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aligned carbon nanotube (CNT) networks; Alignment; Applied sciences; Biological system modeling; Biosensors; Carbon nanotubes; Chemical and biological sensors; Chemical technology; Degradation; Devices; Displays; Electronics; Exact sciences and technology; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Joining processes; Mathematical models; Nanostructure; Nanotubes; Networks; Niobium; percolation threshold; Performance gain; Physics; random CNT networks; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; stick percolation; Studies; Thin film transistors; thin-film transistors (TFTs); transistor models; Transistors; Performance evaluation; High performance; Amorphous material; percolation threshold; Measurement sensor; stick percolation; Carbon nanotubes; Optimization; thin-film transistors (TFTs); Long channel; Singlewalled nanotube; Large area electronics; random CNT networks; Drain current; Percolation; Thin film transistor; transistor models; Current gain; Aligned carbon nanotube (CNT) networks
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2007.898256

Nanobundle thin-film transistors (NB-TFTs) that are based on random networks of single-walled carbon nanotubes are often regarded as high performance alternative to amorphous-Si technology for various macroelectronic applications involving sensors and displays. Here, we use stick-percolation model to study the effect of collective (stick) alignment on the performance of NB-TFTs. For long-channel TFT, small degree of alignment improves the drain current due to the reduction of average path length; however, near-parallel alignment degrades the current rapidly, reflecting the decrease in the number of connecting paths bridging the source/drain. In this paper, we 1) use a recently developed alignment technique to fabricate NB-TFT devices with multiple densities D, alignment thetas, stick length L S , and channel length L C ; 2) interpret the experimental data with a stick- percolation model to develop a comprehensive theory of NB-TFT for arbitrary D,thetas, L S , and L C ; and 3) demonstrate theoretically and experimentally the feasibility of fivefold enhancement in current gain with optimized transistor structure.