Oxidation of atomically thin MoS 2 on SiO 2

摘要: Surface oxidation of MoS 2 markedly affects its electronic, optical, and tribological properties. However, oxidative reactivity of atomically thin MoS 2 has yet to be addressed. Here, we investigate oxidation of atomic layers of MoS 2 using atomic force microscopy and Raman spectroscopy. MoS 2 is mechanically exfoliated onto SiO 2 and oxidized in Ar/O 2 or Ar/O 3 (ozone) at 100-450 C. MoS 2 is much more reactive to O 2 than an analogous atomic membrane of graphene and monolayer MoS 2 is completely etched very rapidly upon O 2 treatment above 300 C. Thicker MoS 2 (> 15 nm) transforms into MoO 3 after oxidation at 400 C, which is confirmed by a Raman peak at 820 cm-1. However, few-layer MoS 2 oxidized below 400 C exhibits no MoO 3 Raman mode but etch pits are formed, similar to graphene. We find atomic layers of MoS 2 shows larger reactivity to O 3 than to O 2 and monolayer MoS 2 transforms …