Catalytic strategies for uniform monolayer MoSe 2 growth in CVD processes

To facilitate the widespread utilization of devices based on two-dimensional transition metal dichalcogenide (TMDC) materials, addressing the challenge of producing large -area and uniform monolayers is crucial. In this study, we investigated the efficacy of various catalysts in promoting the growth of monolayer MoSe 2 through chemical vapor deposition (CVD) as a potential solution to improve surface coverage and uniformity while maintaining the monolayer structure. Five distinct water-soluble catalysts (sodium chloride (NaCl), zinc chloride (ZnCl 2 ), potassium hydroxide (KOH), potassium chloride (KCl), potassium oxalate (K 2 C 2 O 4 )) were employed in conjunction with a glass substrate for the CVD-based growth of monolayer MoSe 2 . We applied these catalyst solutions as thin layers onto SiO 2 /Si substrates to observe their specific catalytic effects on monolayer MoSe 2 formation. MoSe 2 was selected as the target material due to its promising characteristics within the TMDC family, particularly its high mobility. Our findings revealed that NaCl, ZnCl 2 , KCl, and K 2 C 2 O 4 catalysts enhanced monolayer growth in the 2H phase on SiO 2 /Si substrates, while the glass substrate resulted in a hybrid 1T/2H MoSe 2 structure, albeit with the highest surface coverage. Furthermore, the use of a catalyst allowed us to bypass the laborious transfer step by enabling direct growth of the MoSe 2 flakes on the Si/SiO 2 substrate, eliminating the risk of flake damage arising from the transfer process. Among the catalyst solutions, NaCl yielded the most homogeneous MoSe 2 monolayer growth with relatively high coverage.