| 초록 |
Transition metal chalcogenides(TMDs) monolayers such as MoSe2, WS2, etc. exhibit distinct electronic properties due to direct band gap and promise numerous potential applications for next generation photonic and optoelectronic devices. Despite these unique properties originate from monolayer structure, their fabrication has remained difficult due to several limitations- e.g., multilayer formation, oxide residues from precursors, in CVD process. Here we propose a process to fabricate MoSe2 on sapphire via CVD using to promote monolayer deposition. By varying H2 flow rate, MoSe2 growth rate can be modulated and detailed Raman microscopy and PL spectroscopy analysis indicates that H2 plays a key role in precursor reduction, leading to MoSe2 monolayer epitaxy. We hypothesize that the absence of H2 in the nucleation step leads to the optimal mono- or sub-monolayer deposition of metal oxide precursor on substrate, while H2 introduction during the growth step results in the complete reduction of oxides and the epitaxial monolayer formation of MoSe2. Our results provide an important information to fabricate large-area monolayer MoSe2 crucial for a variety of electronic applications. |
