A light emitting diode (LED) including a first-type doped GaN substrate, a first-type doped semiconductor layer, an active layer, a second-type semiconductor layer, a first electrode, and a second electrode is provided. The first-type doped GaN substrate has a first doped element. The first-type semiconductor layer is disposed on the first-type doped GaN substrate. The first-type semiconductor layer has a second doped element different from the first doped element, and the doped concentration of the second doped element—may have a peak from 3E18/cm3 to 1E20/cm3 at an interface between the first-type doped GaN substrate and the first-type semiconductor layer. The active layer is disposed on the first-type semiconductor layer, and the second-type semiconductor layer is disposed on the active layer. The first electrode and the second electrode are respectively disposed on the first-type doped GaN substrate and the second-type semiconductor layer. Other LEDs are also provided.