Controllable growth of monolayer MoS₂by chemical vapor deposition via close MoO₂precursor for electrical and optical applications

Abstract

MoO₂ is used as a new source material for the growth of large area and high optical quality monolayer MoS₂. However, a systematic study of the growth parameters is still missing and large-area growth of discreet single crystals is still challenging. Hereby, we report the shape evolution of monolayer growth of MoS₂ and develop a methodology to achieve centimeter-scaled discrete MoS₂ by adopting MoO₂ as Mo source material in an atmospheric-pressure chemical vapor deposition process. Our results indicate the growth of monolayer MoS₂ could benefit from the precise control of the introduction time of sulfur and the S/MoO₂ ratio in experiments. Micro-Raman and photoluminescence spectra confirm the properties of the material. E-beam lithography was utilized to make contact with the as-grown MoS₂ located at the selective area. The electrical properties of MoS₂ with different morphologies were compared. In the end, the persistent photoconductivity properties of monolayer MoS₂ were emphasized and the underlying mechanism was proposed. These studies demonstrate a better understanding of the growth and application of MoS₂-based 2D materials.