Experimental and Computational Study on the Mechanism of Hydrogen on MoSe2 Growth and Etching in CVD

초록

Transitional metal dichalcogenides (TMDC) have great attractive to electronic, photoelectric devices for its outstanding electric properties. To apply TMDC to various application, it is necessary to provide large-scale and high crystalline monolayer TMDC. Typical synthesis for high quality TMDC is chemical vapor deposition(CVD). In CVD, the hydrogen helps growth of TMDC by reduction of metal oxide precursor, but also it etchs grown-TMDC domain. Metal oxides which remain as impurity could effect on adsorption of hydrogen to TMDC. Here, we have investigated that the existence of metal oxide prevents TMDC monolayer to be desorbed by hydrogen etching. Pure TMDC monolayer and TMDC monolayer with oxide seeds (TMDC+Ox) are treated under hydrogen condition. It is obtained using SEM and AFM analysis that the shape of pure TMDC are changed but TMDC+Ox are not changed much after hydrogen treatment. In energetically, hydrogen prefers to adsorb to metal oxide than atoms in TMDC layer, so that metal oxide hinders etching of TMDC. It also demonstrates that hydrogen supports the growth of TMDC by reducing precursor rather than etching nuclei in nucleation steps. Our research offer insight into the TMDC growth mechanism and pave a way to synthesize high quality TMDC for electronic devices.