Large-area WS2 Deposited on Sapphire and Its In-Plane Raman and PL Spectral Distributions

Abstract Large-area and high-quality WS 2 monolayer has been fabricated on the Al 2 O 3 substrate. Three typical WS 2 configurations were adopted to examine the in-plane spectral properties. For the triangle WS 2 monolayer, the PL light region exhibits a large peak wavelength and could be deduced to be the relaxation of the compressed strain of the WS 2 monolayer and the low defect density. For triangle WS 2 monolayer with multilayer WS 2 on center, combining the peak intensity and position results of PL and Raman spectra, the line traces near the side of the center triangle can be demonstrated to be the defects or dislocations due to the exist of the central multilayer WS 2 . For large-area WS 2 monolayer with crystal domain, PL area integrated mapping shows a uniform light region across the whole surface, except the existing dark crystal domain boundary. The dark line traces could be attributed to compressed strain in the WS 2 monolayer due to the formation of the WS 2 /Al 2 O 3 hybrid structure. The in-plane PL and Raman spectra and mapping exhibited in this work reveal the distribution of stress and defects in this system and further clarify the effects of stress and defects on the optoelectronic properties of WS 2 monolayer on Al 2 O 3 .