Semiconductor light emitting device having a p-type semiconductor layer with a p-type impurity

A semiconductor light emitting device comprising:

• an n-type semiconductor layer;
• a p-type semiconductor layer;
• a light emitting part provided between the n-type semiconductor layer and the p-type semiconductor layer, the light emitting part including a plurality of barrier layers and a plurality of well layers, the well layers being provided between the barrier layers;
• and
• a p-side electrode contacting the p-type semiconductor layer,
• the p-type semiconductor layer including:
• a first p-type layer contacting the p-side electrode and containing a p-type impurity in a first concentration;
• a second p-type layer contacting the light emitting part, containing Al and containing a p-type impurity in a second concentration lower than the first concentration;
• a third p-type layer provided between the first p-type layer and the second p-type layer, the third p-type layer containing a p-type impurity in a third concentration lower than the second concentration;
• and
• a fourth p-type layer provided between the second p-type layer and the third p-type layer, the fourth p-type layer having a concentration of a p-type impurity decreasing from the second concentration to the third concentration along a first direction from the n-type semiconductor layer toward the p-type semiconductor layer.