A light emitting semiconductor device comprising: a first semiconductor layer ; a second semiconductor layer disposed on the first semiconductor layer and comprising V-pits (V); an active layer disposed on the second semiconductor layer including on the V-pits (V), wherein the active layer includes a plurality of well layers and a plurality of barrier layers alternately disposed; a third semiconductor layer having a bandgap wider than that of the barrier layer of the active layer disposed on the active layer including on the V-pits (V); a fourth semiconductor layer disposed on the third semiconductor layer including on the V-pits (V); a fifth semiconductor layer having a bandgap wider than that of the fourth semiconductor layer disposed on the fourth semiconductor layer including on the V-pits (V): and a sixth semiconductor layer disposed on the fifth semiconductor layer , wherein a thickness of the second semiconductor layer is 60 nm to 300 nm wherein the third semiconductor layer and the fifth semiconductor layer comprise an aluminum composition, wherein the fifth semiconductor layer has a bandgap equal to or wider than that of the third semiconductor layer , wherein the fourth semiconductor layer has a bandgap lower than the third semiconductor layer and the fifth semiconductor layer , wherein, a first width (D1) of the V-pits in an upper portion of the active layer , which is parallel to the upper portion of the active layer in the horizontal direction, is smaller than a second width (D2) of the V-pits (V) at an upper portion of the fifth semiconductor layer , which is parallel to the upper portion of the fifth semiconductor layer in the horizontal direction. a first semiconductor layer ; a second semiconductor layer disposed on the first semiconductor layer and comprising V-pits (V); an active layer disposed on the second semiconductor layer including on the V-pits (V), wherein the active layer includes a plurality of well layers and a plurality of barrier layers alternately disposed; a third semiconductor layer having a bandgap wider than that of the barrier layer of the active layer disposed on the active layer including on the V-pits (V); a fourth semiconductor layer disposed on the third semiconductor layer including on the V-pits (V); a fifth semiconductor layer having a bandgap wider than that of the fourth semiconductor layer disposed on the fourth semiconductor layer including on the V-pits (V): and a sixth semiconductor layer disposed on the fifth semiconductor layer , wherein a thickness of the second semiconductor layer is 60 nm to 300 nm wherein the third semiconductor layer and the fifth semiconductor layer comprise an aluminum composition, wherein the fifth semiconductor layer has a bandgap equal to or wider than that of the third semiconductor layer , wherein the fourth semiconductor layer has a bandgap lower than the third semiconductor layer and the fifth semiconductor layer , wherein, a first width (D1) of the V-pits in an upper portion of the active layer , which is parallel to the upper portion of the active layer in the horizontal direction, is smaller than a second width (D2) of the V-pits (V) at an upper portion of the fifth semiconductor layer , which is parallel to the upper portion of the fifth semiconductor layer in the horizontal direction. <EOS>