Promotion of Mo-based Ionic Crystal Precursor for MoS2 Wafer Growth

Abstract

Two-dimensional MoS2 semiconductor has been considered as the promising ingenious solution to extension Moore's law. However, its wafer-scale growth from lab to fab is still in the fancy stages in the field of chip industry. The distribution, concentration and activity of the sulfur-precursor and molybdenum-precursor significantly affect the MoS2 wafter uniform including its grain size, thickness and vacancy. Although the sulfur-precursor has gained much attention, for example, the sulfur source generated from ZnS facilitates the MoS2 growth, the effect of molybdenum-precursor and its growth mechanism is still unclear. In this study, we studied the influence of covalent/ionic molybdenum precursors starting from the principle of chemical vapor deposition and looking for a universal wafer synthesis path. It is found that the reaction speed of Na2MoO4 as a typical ion precursor is very favourable for wafer growth defect control and surface homogeneity compared with MoO3 as a typical covalent precursor. The evaporated [MoO4]2- ion with the smallest cluster has high activity which can easily realize the uniform control of the MoS2 wafer. In addition, the 2-inch monolayer MoS2 film can be grown in the growth time range of 3-5 minutes using ion precursors, which can achieve a mobility of 12 cm2V-1 s -1and maximum IOn/IOff ratio of 9.87×109. This study insights the MoS2 wafer growth mechanism and facilitates the development of a MoS2-based electronics system.