Patent ID: 8525220

Claim:
A light emitting diode (LED), comprising: an N-type semiconductor layer; a P-type semiconductor layer; and an active layer interposed between the N-type semiconductor layer and the P-type semiconductor layer, wherein the P-type semiconductor layer comprises a laminated structure, the laminated structure comprising: a P-type clad layer positioned on the active layer; a hole injection layer positioned on the P-type clad layer; a P-type contact layer positioned on the hole injection layer; and an upper undoped layer interposed between the hole injection layer and the P-type contact layer, the upper updoped layer contacting the hole injection layer, wherein a doping concentration of the hole injection layer is lower than a doping concentration of the P-type clad layer, wherein a bandqap of the P-type clad layer is wider than a bandqap of the hole injection layer, and the bandqap of the hole injection layer is equal to a bandqap of the P-type contact layer, and wherein the hole injection layer, the upper undoped layer contacting the hole injection layer, and the P-type contact layer are semiconductor layers having a substantially identical band gap.