A light-emitting device includes a substrate including a top surface and a first side surface, wherein an area of the top surface is larger than an area of the first side surface, and a light-emitting structure on the first side surface of the substrate, the light-emitting structure having a first-conductivity-type semiconductor layer, a second-conductivity-type semiconductor layer, and an active layer between the first-conductivity-type semiconductor layer and the second-conductivity-type semiconductor layer, wherein the light-emitting structure emits a first light having a first peak wavelength, and wherein an emission area of a first light emitted through the top surface of the substrate is larger than an emission area of a first light emitted through the first side surface of the substrate.