Two-step chemical vapor deposition synthesis of NiTe-MoS vertical junctions with improved MoS transistor performance.

The primary challenge for the widespread application of two-dimensional (2D) electronics is to achieve satisfactory electrical contacts because, during the traditional metal integration process, difficulties arise due to inevitable physical damage and selective doping. Two-dimensional metal-semiconductor junctions have attracted attention for the potential application to achieve reliable electrical contacts in future atomically thin electronics. Here we demonstrate the van der Waals epitaxial growth of 2D NiTe-MoS metal-semiconductor vertical junctions where the upper NiTe selectively nucleates at the edge of the underlying MoS. Optical microscopy (OM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and scanning transmission electron microscope (STEM) studies confirmed that NiTe-MoS metal-semiconductor vertical junctions had been successfully synthesized. The electrical properties of the NiTe-contacted MoS field-effect transistors (FETs) showed higher field-effect mobilities (μ ) than those with deposited Cr/Au contacts. This study demonstrates an effective pathway to improved MoS transistor performance with metal-semiconductor junctions.