Height reversal in Au coverage on MoS_2 flakes/SiO_2: Thermal control of interfacial nucleation

摘要

In this study, we examined the growth of Au over monolayer MoS2 flakes on SiO2/Si(001) substrates at a temperature range of 25-230 degrees C. Based on atomic force microscopy (AFM) images, a height reversal phenomenon was observed after deposition of 2-8nm Au. Depending on the growth temperature and Au coverage, the height difference between the MoS2 flake and the SiO2 area reversed from a single layer height of MoS2 (similar to+0.7 nm) to a range -1.0 to -3.5 nm. This indicates that, based on AFM data, the apparent height of Au/MoS2 is significantly lower than that of Au/SiO2. Scanning electron microscopy results indicate the different lateral nucleation size and shapes of Au coverage on the MoS2 and SiO2 surfaces. In addition, transmission electron microscopy images confirmed the two dimensional and three dimensional growth of Au on the MoS2 and SiO2 surfaces, respectively. The different growth modes of Au on the MoS2 and SiO2 surfaces led to significant changes in the apparent height and thus blocked electrical conduction. These results provide information about nucleation and morphology of Au coverage on MoS2/SiO2 and will be valuable for future applications. Published under license by AIP Publishing.