Light emitting device and method for making the same

A light emitting device comprises a substrate, a semiconductor body, and a transition layer. The semiconductor body is configured to generate light and comprises an n-type layer disposed on the substrate, a p-type layer disposed on the n-type layer, and an active layer disposed between the n-type layer and the p-type layer. The transition layer is disposed on the substrate and located between the n-type layer and the substrate, and comprises a plurality of sub-layers. The plurality of the sub-layers comprise compositions different from each other, and each sub-layer comprise the composition including IIIA metal, transition metal, and nitrogen. The light emitting device further comprises a p-contact layer disposed on the p-type layer of the semiconductor body. A substrate structure and a method for making the light emitting device are also presented.