Intense ultraviolet emission from MgO/ZnS core-shell nanorods induced by subwavelength optical resonant cavity formation

초록

We demonstrated that sheathing well-faceted MgO nanorods, synthesized by the thermal evaporation of Mg3N2, with ZnS (~ 19 nm) resulted in ultraintense ultraviolet luminescence. The intensity ratio of the near-band edge emission to the deep level emission (INBE/IDL) of the MgO-core/ZnS-shell nanorods with a mean shell layer thickness of 19 nm was as high as ~ 23, whereas the INBd/IDL ratio of the bare MgO nanorods was O. This near-band edge emission intensity enhacement by sheathing the MgO nanorods with ZnS IS by far more significant than that by sheathing the ZnS nanorods with other materials including MgO. This is because subwavelength optical resonant cavities form in the MgO/ZnS core-shell nanorods with faceted surfaces whereas they do not form in the ZnS-core/MgO (or other material)-shell nanorods with no faceted surfaces.