  The defect-free transfer of chemical vapour deposition (CVD) grown monolayer
MoS2 is important for both fabrication of 2D devices and fundamental point of
view for various studies where substrate effects need to be minimized. Among
many transfer techniques, two well-known techniques that use the polymer as
carriers are wet-transfer technique and the surface-energy-assisted transfer
technique. In this work, we transferred a single CVD grown monolayer MoS2 by
these two transfer methods on a similar substrate, and the intervention of
strain and defects in the transfer process is probed by Raman and
photoluminescence (PL) spectroscopy, respectively. We found that the
conventional and commonly used wet transfer technique degraded the monolayer
due to KOH contamination. In contrast, monolayers transferred using the
surface-energy-assisted transfer method possess structural integrity and
optical quality on a par with the as-grown MoS2 layers. As compared to the wet
process a strain-free transfer was recorded in the surface-energy-assisted
technique using Raman spectroscopic studies.
