Self-patterning of liquid Field's metal for enhanced performance of two-dimensional semiconductors

Abstract

Two-dimensional (2D) van der Waals semiconductors show promise for atomically thin, flexible, and transparent optoelectronic devices in future technologies. However, developing high-performance field-effect transistors (FETs) based on 2D materials is impeded by two key challenges, namely, the high contact resistance at the 2D semiconductor–metal interface and limited effective doping strategies. Here, we present a novel approach to overcome these challenges using self-propagating liquid Field's metal, a eutectic alloy with a low melting point of approximately 62 °C. By modifying pre-patterned electrodes on WSe₂ FETs through the deposition of Field's metal onto contact pad edges followed by vacuum annealing, we create new semimetal electrodes that seamlessly incorporate the liquid metal into 2D semiconductors. This integration preserves the original electrode architecture while transforming to semimetal compositions of Field's metal, such as Bi, In, and Sn, modifies the work functions to 2D semiconductors, resulting in reduced contact resistance without inducing Fermi-level pinning, and improves charge carrier mobilities. Our method enhances the electrical performance of 2D devices and opens new avenues for designing high-resolution liquid metal circuits suitable for stretchable, flexible, and wearable 2D semiconductor applications.