Healing Sulfur Vacancies in Monolayer MoS₂ by High-Pressure Sulfur and Selenium Annealing: Implication for High-Performance Transistors

Developing a technology to terminate chalcogen vacancies for transition-metal dichalcogenides is a crucial task for applications, such as transistors, diodes, and sensors, because chalcogen vacancies degrade the electronic and optical properties. This article reports a healing method of S vacancies in MoS2 by high-pressure annealing under a S vapor pressure of 5 atm. The crystal quality after mechanical transfer, S annealing, and vacuum annealing was systematically studied by observing the photoluminescence (PL). The remarkable recovery of the A-exciton emission peak in the PL spectrum indicated repair of the crystal quality in MoS2 by the S annealing. We also demonstrated that the S vacancies could be terminated by Se atoms using a high-pressure annealing method. The crystal quality of MoS2(1–x)Se2x alloys was confirmed by transmission electron microscopy and electron diffraction.