A semiconductor device according to an embodiment comprises: a substrate; a buffer layer provided on the substrate; a first conductivity type semiconductor layer provided on the buffer layer; a second conductivity type semiconductor layer; a light emitting structure, provided between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer, comprising an active layer which emits ultraviolet light; and a plurality of air voids provided within the buffer layer, wherein the air voids can be formed to have two or more inclined surfaces.