Direct Growth of WSe2 on SiO2 by Chemical Vapor Deposition with Seeding Promoter
Han Yeh1*, Zhen-Yu Juang1, Wen-Hao Chang1
1Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
* presenting author:Han Yeh, email:maggieyeh15@yahoo.com.tw

Direct growth of large-area two-dimensional (2D) materials on suitable substrate is essential for mass production and on-chip integrations. Chemical vapor deposition (CVD) has been demonstrated to be useful for the growth of high-quality and large-area monolayer transition metal dichalcogenides (TMDCs) on sapphire substrates. For device applications, the CVD-grown TMDC monolayers on sapphires must be transferred onto SiO2/Si substrates for fabrications of back-gate or front-gate contacts. However, structural defects and contaminations were inevitably created during the transfer processes. While direct growth of TMDCs on SiO2/Si substrate is preferable, the amorphous surface of SiO22makes homogeneous nucleation of TMDCs very difficult. In this works, we used organic molecules, perylene-tetracarboxylicacid-dianhydride (PTCDA), as seeding promoters to grow monolayer WSe2 on SiO2 substrates. Heterogeneous nucleations provided by organic molecules effectively reduce the formation energy of WSe2 nuclei in comparison with homogeneous nucleation. We found that the PTCDA seeding promoters facilitate lateral growth of monolayer WSe2 with single-crystalline grain size will up to 40 μm. Experimentally, we observed that the WSe2 monolayers on SiO2 exhibit stronger photoluminescence and Raman intensities than that on sapphire substrates. The WSe2 monolayers grown on SiO2/Si substrates have also been fabricated into field-effect transistors, which shows improved electrical performance comparing with that fabricated through transfer processes. The PTCTA seeding promoters work not only on SiO2, but also on the quartz substrates.


Keywords: WSe2, seeding promoter, transition metal dichalcogenides