Group iii nitride semiconductor light-emitting device

Abstract

An object of the present invention is to provide a Group III nitride semiconductor light-emitting device with high emission efficiency. The inventive Group III nitride semiconductor light-emitting device has an n-type layer, a light-emitting layer and a p-type layer composed of a Group III nitride semiconductor on a substrate, with the light-emitting layer sandwiched between the n-type layer and p-type layer, wherein the range for Δa as the ratio of the difference between the a-axis lattice constant of the layer between the light-emitting layer and substrate (or in the case of multiple layers with different compositions between the light-emitting layer and substrate, where each layer is grouped according to composition, the a-axis lattice constant of the group having the maximum thickness considering all of the layers belonging to the group) aand the a-axis lattice constant of the light-emitting layer (or if the light-emitting layer has a multiple quantum well structure, the a-axis lattice constant determined from the zero-order peak representing the average composition of the well layers and barrier layers) a, represented by the following formula (I), is −0.05≦Δa≦0.05 (unit: %).Δ=100(-)/  (I)