Light emitting device and lighting system

A light emitting device comprising:

• a first electrode;
• a first semiconductor layer disposed on the first electrode and including a first conductive dopant;
• a second semiconductor layer disposed on the first semiconductor layer and including the first conductive dopant having a doping concentration lower than a doping concentration of the first semiconductor layer;
• a third semiconductor layer disposed on the second semiconductor layer to adjust stress;
• a first conductive semiconductor layer on the third semiconductor layer;
• an active layer on the first conductive semiconductor layer;
• a second conductive semiconductor layer on the active layer;
• and
• a second electrode on the second conductive semiconductor layer,
• wherein the third semiconductor layer has a doping concentration in a range between the doping concentration of the second semiconductor layer and a doping concentration of the first conductive semiconductor layer, and the doping concentration of the third semiconductor layer is increased toward the first conductive semiconductor layer, and
• wherein the first conductive semiconductor layer includes the first conductive dopant having a doping concentration higher than a doping concentration of the second semiconductor layer and the third semiconductor layer.