A light-emitting layer includes: a base layer with a plurality of base segments that have a composition subject to stress strain from a first semiconductor layer and are formed in a random net shape; and a quantum well structure layer including at least one quantum well layer and at least one barrier layer that are formed on the base layer. The base layer includes: a first sub-base layer; a trench that partitions the first sub-base layer for each of the plurality of base segments; and a second sub-base layer formed to bury the first sub-base layer.