Selective oxidation of the surface layer of bilayer WSe₂ by laser heating

WSe₂ films have several anisotropies between the in-plane and out-of-plane directions, which affects their responses to external operation. Guided by the anisotropies, we provide adequate heat propagation to oxidize selectively the surface layer of bilayer WSe₂ and characterized the structure of monolayer WSe₂ covered with an oxidized layer by optical and atomic force microscopy, Raman spectroscopy and photoluminescence measurements. Furthermore, we found indications that laser treatments of monolayer WSe₂ covered with an oxidized layer have possibility to cause photoactivated oxidation. Our observations suggest clues to understand low-dimensional oxidation behaviours.