Iodide-substitution-induced phase transition of chemical-vapor-deposited MoS2

Abstract

Molybdenum disulfide (MoS₂)-based electronic devices, particularly field effect transistors, have outstanding performance. However, a large contact resistance between electrode metals and MoS₂ limits the full potential of these devices. Here we report an effective, rapid, and convenient approach to inducing phase transitions of MoS₂via treatment with a potassium iodide (KI) solution during device fabrication. The transition from the 2H to the 1T phase in monolayer MoS₂ was confirmed using Raman spectroscopy and transmission electron microscope imaging. In electrical transport measurements of the MoS₂ transistors subjected to the phase-transition treatment, the normalized on-state current was nearly 50 times greater than that of an untreated transistor. The treatment also resulted in a greater on–off ratio, better output characteristics and a significantly lower contact resistance owing to the phase transition of MoS₂. Hence, we report a new method for inducing a phase transition of MoS₂ and provide a reasonable mechanism for this phase transition, offering a new and efficient approach to improved MoS₂ devices.