Patent ID: 8362459

Claim:
A light emitting device comprising: a substrate; a light-emitting structure layer on the substrate, the light-emitting structure layer including a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer between the first and second conductive type semiconductor layers; and a light-transmitting electrode layer on the second conductive type semiconductor layer, wherein the second conductive type semiconductor layer has a thickness satisfying Equation (1): 2·Φ1+Φ2 =N· 2π±Δ,(0≦Δ≦π/2) (1) where Φ1 is a phase change that is generated when light of a vertical direction passes through the second conductive type semiconductor layer, Φ2 is a phase change that is generated when the light is reflected by the light-transmitting electrode layer, and N is a natural number, wherein Φ1 is expressed as Equation (2): Φ1=2 πn 2 d/λ (2) where n 2 is a refractive index of the second conductive type semiconductor layer, λ is a wavelength of light emitted from the active layer, and d is the thickness of the second conductive type semiconductor layer, wherein the active layer has a thickness equal to or less than λ/n 1 , where n 1 is a refractive index of the active layer, wherein all layers between the active layer and the substrate are formed in a nitride-based semiconductor.