A light emitting device for emitting UVC radiation. The device comprises a substrate and a patterned layer. The patterned layer comprises a plurality of mask regions on the substrate. Exposed portions of the substrate are disposed between the mask regions. A plurality of nanostructures are disposed on the exposed portions of the substrate and over the mask regions, the plurality of nanostructures being a single crystal semiconductor and comprising a core tip. An active layer is disposed over the plurality of nanostructures. The active layer is a quantum well structure and comprises at least one material chosen from AlN, AlGaN and GaN. A p-doped layer is disposed over the active layer. Both the active layer and the p-doped layer are conformal to the plurality of nanostructures so as to form an emitter tip over the core tip.