UV light emitting diode and method of fabricating the same

An UV light emitting device comprising:

• a first semiconductor layer having a first type conductivity;
• an electron blocking layer disposed on a first surface of the first semiconductor layer;
• an active layer disposed on the electron blocking layer;
• a second semiconductor layer disposed on the active layer and having a second type conductivity;
• an electrode disposed on the second semiconductor layer and electrically connected to the second semiconductor layer, the electrode structured to provide electric current to the second semiconductor layer;
• a reflective metal layer disposed on a second surface of the first semiconductor layer that is opposite to the first surface of the first semiconductor layer and including a material having reflectivity with respect to UV light;
• and
• a metal material disposed on the reflective metal layer to be opposite to the first semiconductor layer and electrically connected to the first semiconductor layer;
• wherein the second semiconductor layer has a surface with roughness through which the UV light is extracted to an outside,
• the second semiconductor layer has Al content changing along a thickness direction of the second semiconductor layer, and
• a rate of the change of Al content in the second semiconductor layer varies along a thickness direction of the second semiconductor layer, and
• wherein the second semiconductor layer includes a first portion that includes AlxGa(1-x)N with a first doping concentration and a second portion that includes AlyGa(1-y)N with a second doping concentration different from the first doping concentration and wherein x decreases along a direction towards the surface of the second semiconductor layer and y gradually increases in the direction, wherein x has a range of 0<x<1 and y has a range of 0<y<1.