In this project, we propose to develop the baseline process to form low source-drain contact resistance to the CNTs. This includes finding the right metal stack and annealing recipe to form good ohmic contact to the CNTs. The goal is to achieve a resistance less than 25 k? at per nanotube contact. To reach such goal, we will leverage the interfacial dipole alignment of conjugated polyelectrolytes to form ohmic contact between metal and semiconducting materials developed in Professor Guillermo C. Bazans group. We will leverage our aerosol jet printing technology to precisely deposit carbon nanotube thin film inside drain/source contacts. This will reduce etching step using plasma or electron beam which could generate doping or defects. The carbon nanotube ink will be single chirality (6,5) single-walled carbon nanotubes extracted from high pressure carbon monoxide raw powder. Such a super pure carbon nanotube is less defective. Moreover, the uniform diameter of carbon nanotubes can mitigate the variation of electric properties including contact resistance. The end outcome is to develop a high-linearity Carbon Nanotube Field Effect Transistor (CFET) for RF amplification to dramatically improve the power and spectral efficiencies in wireless communication.;
Benefit: Broader impacts include (1) pin-to-pin drop in replacement RF transistors for radio communication products, (2) discrete power amplifier modules for base stations and Wireless semiconductor devices in popular products such as smartphones, tablets and mobile devices accounting for over half of the demand for semiconductors. Given this rapid increase, the demand placed on RF transistor devices is ever so important. Needs for increased functionality in terms of operating frequency, linearity and cost is required to enable the communication explosion. Our approach is to go beyond traditional semiconductor device solutions based on Si and III-V by evoking ballistic transport regimes in one dimensional nanomaterials such as carbon nanotubes (CNT). Ballistic device transport allows for ultimate device efficiency and spectral linearity to accommodate for 4G interference averaging techniques such as frequency hopping where spectral efficiency, filter technology and interference cancellation is falling short. RF CNT devices have the potential to offer higher bandwidth (GHz operation towards THz), improved linearity (less radio elements and filtering demands), higher efficiency (increased battery life) and compatibility with existing CMOS integration processes (reduced cost).
