Patent ID: 8653551

Claim:
A light-emitting element having a front surface and a back surface and adapted to extract light from the back surface with the front surface facing down, the light-emitting element comprising: a substrate transparent to a light-emitting wavelength λ and defining the back surface; an n-type nitride semiconductor layer provided on the substrate; a light-emitting layer which is provided on the n-type nitride semiconductor layer and emits light at the light-emitting wavelength λ; a p-type nitride semiconductor layer provided on the light-emitting layer; a transparent electrode layer which is provided on the p-type nitride semiconductor layer and is transparent to the light-emitting wavelength λ of the light-emitting layer; and a reflective electrode layer which is provided on the transparent electrode layer and reflects light passing through the transparent electrode layer toward the back surface; wherein the transparent electrode layer has a thickness T satisfying the following expression (1): 3 ⁢ λ 4 ⁢ ⁢ n + 0.30 × ( λ 4 ⁢ ⁢ n ) ≤ T ≤ 3 ⁢ λ 4 ⁢ ⁢ n + 0.45 × ( λ 4 ⁢ ⁢ n ) ( 1 ) wherein λ is the light-emitting wavelength of the light-emitting element, and n is a refractive index of the transparent electrode layer.