Light emitting device and light emitting device structure

A light emitting device including a epitaxial structure, a first electrode and a second electrode is provided. The epitaxial structure has a first surface and a second surface opposite to each other, a plurality of first dislocation density regions and a plurality of second dislocation density regions. The first dislocation density regions and the second dislocation density regions are alternately arranged between the first surface and the second surface. The dislocation density of each first dislocation density region is lower than the dislocation density of each second dislocation density region and the quantity of the first dislocation density regions are at least ten. The epitaxial structure further includes a light emitting layer, a first-type semiconductor layer and a second-type semiconductor layer disposed on two opposite sides of the light emitting layer. The first electrode and the second electrode are electrically connected to the first-type semiconductor layer and the second-type semiconductor lay