The Woodruff School

SUMMARY

Carbon nanotubes (CNTs) are known for their exceptional electrical, thermal, mechanical, optical, and chemical properties. Presently, the commercial use of CNTs is limited to a few products such as rechargeable batteries, automotive parts, and sporting goods. However, the recent advances in CNTs synthesis, purification and assembly have paved the way for their application in microelectronics. In particular, CNT network based thin-film devices and composites have been explored for a range of electronics applications such as flexible e-displays, sensors, RFID tags and antennas. The proposed work investigates the properties and performance of CNT network based devices and composites with focus on: (1) CNT network thin-film transistors (CN-TFTs) and (2) CNTs doped liquid crystals (LCs). CNT networks in CN-TFTs are typically supported on thermally insulating substrates such as glass or plastics which have very low thermal conductivity. In the absence of active cooling mechanism, the excessive self-heating in these devices can lead to the breakdown causing performance and reliability issues. A self-consistent electro-thermal computational model is developed and employed in order to investigate the issues related to the heat dissipation and reliability of CN-TFTs. The modeling framework predicts the current and temperature profile of percolating CNT network and the supporting structure. The model is validated against the experimental results. The computational method allows to examine the role of various device parameters such as network morphology (i.e., network density, CNT junction topology, and CNT length and alignment distribution) and channel geometry (i.e., channel length and width) on heat dissipation and thermal reliability of CN-TFTs. High-field breakdown study of CN-TFTs is conducted which provides useful guidelines for the design and optimization of the CN-TFTs with respect to the aforementioned parameters in order to enhance the performance and reliability. A mesoscopic simulation technique, dissipative particle dynamics, is employed to understand the dynamics of CNT-doped-LCs systems under electric field.

SUBJECT:	Ph.D. Proposal Presentation

BY:	Man Prakash Gupta

TIME:	Friday, September 27, 2013, 10:00 a.m.

PLACE:	MRDC Building, 4211

TITLE:	Numerical Investigation of Carbon Nanotube Network Thin-film Composites and Devices

COMMITTEE:	Dr. Satish Kumar, Chair (Mechanical Engineering) Dr. Baratunde Cola (Mechanical Engineering) Dr. Alexander Alexeev (Mechanical Engineering) Dr. Manos Tentzeris (Electrical Engineering) Dr. Abhijit Chatterjee (Electrical Engineering)

SUMMARY Carbon nanotubes (CNTs) are known for their exceptional electrical, thermal, mechanical, optical, and chemical properties. Presently, the commercial use of CNTs is limited to a few products such as rechargeable batteries, automotive parts, and sporting goods. However, the recent advances in CNTs synthesis, purification and assembly have paved the way for their application in microelectronics. In particular, CNT network based thin-film devices and composites have been explored for a range of electronics applications such as flexible e-displays, sensors, RFID tags and antennas. The proposed work investigates the properties and performance of CNT network based devices and composites with focus on: (1) CNT network thin-film transistors (CN-TFTs) and (2) CNTs doped liquid crystals (LCs). CNT networks in CN-TFTs are typically supported on thermally insulating substrates such as glass or plastics which have very low thermal conductivity. In the absence of active cooling mechanism, the excessive self-heating in these devices can lead to the breakdown causing performance and reliability issues. A self-consistent electro-thermal computational model is developed and employed in order to investigate the issues related to the heat dissipation and reliability of CN-TFTs. The modeling framework predicts the current and temperature profile of percolating CNT network and the supporting structure. The model is validated against the experimental results. The computational method allows to examine the role of various device parameters such as network morphology (i.e., network density, CNT junction topology, and CNT length and alignment distribution) and channel geometry (i.e., channel length and width) on heat dissipation and thermal reliability of CN-TFTs. High-field breakdown study of CN-TFTs is conducted which provides useful guidelines for the design and optimization of the CN-TFTs with respect to the aforementioned parameters in order to enhance the performance and reliability. A mesoscopic simulation technique, dissipative particle dynamics, is employed to understand the dynamics of CNT-doped-LCs systems under electric field.