Anomalous enhancement oxidation of few-layer MoS_(2)and MoS_(2)/h-BN heterostructure

Because of profound applications of two-dimensional molybdenum disulfide(MoS_(2))and its heterostructures in electronics,its thermal stability has been spurred substantial interest.We employ a precision muffle furnace at a series of increasing temperatures up to 340℃to study the oxidation behavior of continuous MoS_(2)films by either directly growing mono-and fewlayer MoS_(2)on SiO_(2)/Si substrate,or by mechanically transferring monolayer MoS_(2)or hexagonal boron nitride(h-BN)onto monolayer MoS_(2)substrate.Results show that monolayer MoS_(2)can withstand high temperature at 340℃with less oxidation while the few-layer MoS_(2)films are completely oxidized just at 280℃,resulting from the growth-induced tensile strain in few-layer MoS_(2).When the tensile strain of films is released by transfer method,the stacked few-layer MoS_(2)films exhibit superior thermal stability and typical layer-by-layer oxidation behavior at similarly high temperature.Counterintuitively,for the MoS_(2)/h-BN heterostructure,the h-BN film itself stacked on top is not damaged and forms many bubbles at 340℃,whereas the underlying monolayer MoS_(2)film is oxidized completely.By comprehensively using various experimental characterization and molecular dynamics calculations,such anomalous oxidation behavior of MoS_(2)/h-BN heterostructure is mainly due to the increased tensile strain in MoS_(2)film at elevated temperature.