Transmission Line Modeling and Statistic Analysis of Nanoscale Tunneling Electrical Contacts

The growing popularity of novel electronic circuits based low-dimensional materials, such as carbon nanotubes (CNTs), has made contact engineering crucial. CNT based devices, in particular, experience significant challenges because of the inter-tube connections. On a macroscopic level, the exceptional intrinsic electrical properties of CNTs become elusive [1]. Contact resistances between CNTs profoundly affect the electron transport and reduce the electrical conductivity of carbon nanofiber (CNF) [2] and greatly limit the performance of CNT thin film based Field Effect Transistors (FETs). In the partially overlapped parallel contacts between CNTs, the tunneling effects plays an important role for the macroscopic conductivity of CNF [3]. By coupling the transmission line model and tunneling current, a self-consistent contact model was established to solve the current and voltage distribution along the contact length and the overall contact resistance for various electrical contact dimensions (contact length and thickness of interface layer), input voltage and material properties [4]. With the self-consistent model, statistical analysis is performed by changing the contact length and gap distance using Gaussian distributions. The resulted conductivity of the fiber is to be compared with experimental measurements [5].