A light emitting diode (100, 100A, 100B, 150, 151) comprising: a first conductivity type semiconductor layer doped with an type dopant; an active layer consisting of a plurality of barrier layers and a plurality of well layers alternately disposed on the first conductivity type semiconductor layer; and a second conductivity type semiconductor layer on the active layer, the second conductivity type semiconductor layer being doped with a p type dopant; wherein a defect density on a surface of the active layer is lower than a defect density on a surface of the first conductivity type semiconductor layer, wherein at least one well layer of the plurality of well layers includes an indium (In) cluster having a density of 1E11/cm 2 to 1E13/cm 2, wherein the at least one well layer has a thickness of 3nm to 4nm which is thinner than a thickness of at least one barrier layer of the plurality of barrier layers, wherein the at least one well layer includes a material having a compositional formula ofIn x Al y Ga (1-x-y) N with 0<x≤1, 0≤y≤1, 0<x+y≤1 wherein a first barrier layer of the plurality of barrier layers closer to the first conductivity type semiconductor layer than the second conductivity type semiconductor layer includes the n type dopant, and wherein the defect density of a second barrier layer of the plurality of barrier layers nearer to the second conductivity type semiconductor layer than the first conductivity type semiconductor layer is lower than the defect density of the first barrier layer nearer to the first conductivity type semiconductor layer than the second conductivity type semiconductor layer, characterised in that the first barrier layer of the plurality of barrier layers does not have the same composition as the first conductivity type semiconductor layer. a first conductivity type semiconductor layer doped with an type dopant; an active layer consisting of a plurality of barrier layers and a plurality of well layers alternately disposed on the first conductivity type semiconductor layer; and a second conductivity type semiconductor layer on the active layer, the second conductivity type semiconductor layer being doped with a p type dopant; wherein a defect density on a surface of the active layer is lower than a defect density on a surface of the first conductivity type semiconductor layer, wherein at least one well layer of the plurality of well layers includes an indium (In) cluster having a density of 1E11/cm 2 to 1E13/cm 2, wherein the at least one well layer has a thickness of 3nm to 4nm which is thinner than a thickness of at least one barrier layer of the plurality of barrier layers, wherein the at least one well layer includes a material having a compositional formula ofIn x Al y Ga (1-x-y) N with 0<x≤1, 0≤y≤1, 0<x+y≤1 wherein a first barrier layer of the plurality of barrier layers closer to the first conductivity type semiconductor layer than the second conductivity type semiconductor layer includes the n type dopant, and wherein the defect density of a second barrier layer of the plurality of barrier layers nearer to the second conductivity type semiconductor layer than the first conductivity type semiconductor layer is lower than the defect density of the first barrier layer nearer to the first conductivity type semiconductor layer than the second conductivity type semiconductor layer, characterised in that the first barrier layer of the plurality of barrier layers does not have the same composition as the first conductivity type semiconductor layer.