Electrical contacts to few-layer MoS₂ with phase-engineering and metal intercalation for tuning the contact...

Due to Fermi-level pinning in metal-two-dimensional MoS₂ junctions, improving the performance of MoS₂-based electrical devices is still under extensive study. The device performance of few-layer MoS₂ depends strongly on the number of layers. In this work, via density-functional theory calculations, a comprehensive understanding from the atomistic view was reached for the interlayer interaction between metal and few-layer MoS₂ with phase-engineering and intercalation doping, which are helpful for improving the contact performance. These two methods are probed to tune the performance of few-layer MoS₂-based field-effect transistors, and both of them can tune the Schottky barrier height. Phase-engineering, which means that the MoS₂ layer in contact with metal is converted to the T phase, can transform the Schottky barrier from n- to p-type. Intercalation doping, which takes advantage of annealing and results in metal atom interaction in between MoS₂ layers, makes the MoS₂ layers become quasi-freestanding and converts the indirect bandgap into direct bandgap. Our atomistic insights help improve the performance of few-layer MoS₂-based electronic devices.