Multilayer MoS2 prepared by one-time and repeated chemical vapor depositions: anomalous Raman shifts and transistors with high ON/OFF ratio

We show that multilayer molybdenum disulfide (MoS2) grown with the chemical vapor deposition (CVD) may exhibit quite distinct behaviors of Raman shifts from those of exfoliated ones. The anomalous Raman shifts depend on CVD growth modes and are attributed to the modified dielectric screening and interlayer coupling of MoS2 in various growth conditions. With repeated CVD growths, we demonstrated the precise control over the layer number of MoS2. A decently large drain current, high ON/OFF ratio of 10(5), and enhanced field-effect mobility can be achieved in transistors fabricated on the six-layer MoS2.