A light emitting device can be used for light emitting diodes and laser diodes. The light emitting device includes a substrate, a first semiconductor layer on the substrate, a second semiconductor layer on the first semiconductor layer, and a multi-quantum well structure including at least one well layer and at least one barrier layer between the first and second semiconductor layers. A carrier trap portion is formed in at least one layer within the multi-quantum well structure. The carrier trap portion has a band-gap energy that gradually decreases from a periphery of the carrier trap portion to a center thereof.