Chemical vapor deposition of clean and pure MoS2 crystals by the inhibition of MoO3−x intermediates

Abstract

Molybdenum disulfide (MoS₂) synthesized via chemical vapor deposition (CVD) is commonly accompanied by some intermediate products in the form of MoO_3−x, resulting in MoS₂–MoO_3−x hybrids with diverse structures. In this study, we show that through the rational design of heating evaporation rate of the precursors of sulfur and MoO₃ separately in a CVD system with double temperature zones, the intermediate product of MoO_3−x involved in the CVD growth of MOS₂ (generally in the form of quadrilateral MoO₂/MoS₂ composites and/or stacks of quadrilateral MoO₂/triangular MoS₂) can be inhibited largely. On this basis, the appropriate sulfur sublimation versus the evaporated MoO₃ powder is revealed to be the key factor for the inhibition of intermediates, obtaining high-quality MoS₂ crystals with as high as >90% cleanness/purity. This study will assist our understanding of the fundamental CVD growth mechanisms of transition metal dichalcogenides (TMDCs) and provides a facile direction for the controlled synthesis of high-quality MoS₂ and other TMDCs with or without intermediate hybrids for applications.