Femtosecond Laser Irradiation-Mediated MoS-Metal Contact Engineering for High-Performance Field-Effect Transistors and Photodetectors.

2D materials exhibit intriguing electrical and optical properties, making them promising candidates for next-generation nanoelectronic devices. However, the high contact resistance of 2D materials to electrode material often limits the ultimate performance and potential of 2D materials and devices. In this work, we demonstrate a localized femtosecond (fs) laser irradiation process to substantially minimize the resistance of MoS-metal contacts. A reduction of the contact resistance exceeding three orders of magnitude is achieved for mechanically exfoliated MoS, which remarkably improves the overall FET performance. The underlying mechanisms of resistance reduction are the removal of organic contamination induced by the transfer process, as well as the lowering of Schottky barrier resistance () attributed to interface Fermi level pinning (FLP) by Au diffusion, and the lowering of interlayer resistance () due to interlayer coupling enhancement by Au intercalation under fs laser irradiation. By taking advantage of the improved MoS-metal contact behavior, a high-performance MoS photodetector was developed with a photoresponsivity of 68.8 A W at quite a low of 0.5 V, which is ∼80 times higher than the pristine multilayer photodetector. This contamination-free, site-specific, and universal photonic fabrication technique provides an effective tool for the integration of complex 2D devices, and the mechanism of MoS-metal interface modification reveals a new pathway to engineer the 2D material-metal interface.