Unveiling Metal–CNT Interfacial Wetting and Coverage in Aligned Carbon Nanotube Array-Based Field Effect Transistors

The interface between metal contacts and aligned, high-density carbon nanotube arrays (A-CNTs) critically impacts CNT field-effect transistor (FET) performance, yet fundamental understanding is hindered by complex packing and intertube variability. Here, we employ cross-sectional high-resolution transmission electron microscopy (X-TEM) to investigate contact interfaces between A-CNTs and five key metals (Pd, Pt, Au, Sc, and Y) in FET structures. We introduce quantitative parameters for interfacial wetting (derived parameter ω_<i>CM</i>) and metal coverage (<i>C</i>_<i>CM</i>) to analyze varied array morphologies. Our results reveal a transition from wetting to nonwetting behavior with increasing CNT density, significantly affecting metal coverage and, consequently, contact resistance. By correlating microscopic interface structure with electrical performance, we identify an optimal A-CNT density range for contact engineering and benchmark predicted contact resistance scaling against advanced technology node requirements. This work establishes a quantitative microscopic framework for understanding metal-A-CNT interfaces, offering practical design guidance for high-performance, CMOS-compatible CNT electronics.