Promotion of a Mo-based ionic crystal precursor for MoS wafer growth

Two-dimensional MoS 2 semiconductors have emerged as a promising solution for extending Moore's law. Nevertheless, their wafer-scale growth from lab to fab is still in infancy stages within the semiconductor industry. The distribution, concentration, and reactivity of both sulfur and molybdenum precursors exert a substantial influence on the uniformity of MoS 2 wafers, including on parameters such as the grain size, thickness, and vacancy density. While considerable emphasis has been directed towards sulfur precursors-such as those derived from ZnS, which facilitate MoS 2 growth-the role of molybdenum precursors and their associated growth mechanisms remain inadequately understood. In this study, we investigated the effects of covalent and ionic molybdenum precursors, grounded in the principles of chemical vapor deposition, with the aim of identifying a universal synthesis pathway for wafer production. Our findings indicate that the reaction kinetics of Na 2 MoO 4 , a representative ionic precursor, are particularly advantageous for controlling wafer growth defects and enhancing surface homogeneity in comparison to those of MoO 3 , a conventional covalent precursor. Evaporated [MoO 4 ] 2− ions, characterized by their smaller cluster size, exhibited high reactivity, facilitating uniform control over MoS 2 wafer characteristics. Furthermore, we demonstrate that a 2-inch monolayer MoS 2 film could be synthesized within a growth timeframe of 3-5 minutes using ionic precursors, achieving a mobility of 12 cm 2 V −1 s −1 and a maximum I on / I off ratio of 9.87 × 10 9 . This study elucidates the growth mechanisms of MoS 2 wafers and contributes to the advancement of MoS 2 -based electronic systems. The influence of covalent/ionic molybdenum precursors on the quality of MoS 2 is investigated. It is found that the reaction of Na 2 MoO 4 as a typical ionic precursor is highly favourable for defect control and surface homogeneity in wafer growth.