The roles of H2 in TMDC synthesis by CVD

초록

The monolayer (or few-layer) transitional metal dichalcogenides(TMDC) attract attention for its unique electrical properties. A typical method for synthesis of TMDC is chemical vapor deposition(CVD). Monolayer MoSe2, heterostructure MoSe2/MoS2 or MoSe2/WSe2 are synthesized by using CVD method. In CVD, hydrogen gas plays role as creating reduction condition to make easy decomposition of metal precursor, MoO3, and etching as-grown MoSe2 layers. In our study, the effect of an existence of hydrogen in CVD process is observed by SEM, AFM, Raman, and PL spectroscopy. The mechanism of MoSe2 growth is comprehended by insitu controlling hydrogen flux in nucleation step and growth step. As a result, the structure and shape of MoSe2 are controlled.