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 ωCM) and metal coverage (CCM) 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.