A semiconductor device is provided. The semiconductor device includes a first semiconductor layer; a second semiconductor layer on the first semiconductor layer; an active region between the second semiconductor layer and the first semiconductor layer; an electron blocking structure on the active region; a first In-containing layer between the active region and the electron blocking structure; and a second In-containing layer on the electron blocking structure; wherein the first In-containing layer has a first indium content, the second In-containing layer has a second indium content, and the second indium content is different from the first indium content.