Semiconductor light emitting device with light extraction surface
A semiconductor light emitting device which includes at least one concave on a light extraction surface opposite to a surface on which a semiconductor stack comprising a light emitting layer between a n-type semiconductor layer and a p-type semiconductor layer is mounted. The concave has not less than two slopes each having a different slope angle in a direction that a diameter of the concave becomes narrower toward a bottom of the concave from an opening of the concave and a slope having a gentle slope angle is provided with irregularities and a slope having a steep slope angle is a flat surface.
1. A semiconductor light emitting device comprising:
a semiconductor stack comprising an n-type semiconductor layer, a p-type semiconductor layer, and a light emitting layer between the n-type semiconductor layer and the p-type semiconductor layer,
wherein the semiconductor stack includes at least one concave structure,
wherein the concave structure has two slopes each having a different slope angle in a direction that a diameter of the concave structure becomes narrower toward a bottom of the concave structure from an opening of the concave structure,
wherein an upper surface of the semiconductor stack includes a higher planar portion outside the concave structure and a lower surface of the semiconductor stack includes a lower planar portion inside the concave structure,
wherein the two slopes connect the higher planar portion to the lower planar portion,
wherein a slope, of the two slopes, having a gentler slope angle is provided with irregularities and a slope, of the two slopes, having a steeper slope angle is a flat surface, and
wherein a depth of the concave structure has a length not less than half of a thickness between the upper surface and a top surface of the light emitting layer and less than the thickness between the upper surface and the top surface of the light emitting layer.
2. The semiconductor light emitting device according to claim 1 , wherein the slope of the concave structure having the gentler slope angle is closer to the opening of the concave structure than the slope having the steeper slope angle.
3. The semiconductor light emitting device according to claim 1 , wherein the lower surface is provided with irregularities.
4. The semiconductor light emitting device according to claim 1 , wherein a plurality of the at least one concave structure is disposed on a light extraction surface of the semiconductor stack, wherein adjacent openings of the plurality of the concave structures are separated from each other by the upper surface, and wherein the upper surface is provided with irregularities.
5. The semiconductor light emitting device according to claim 1 , wherein an electrode is disposed on a light extraction surface of the semiconductor stack.
6. The semiconductor light emitting device according to claim 1 , wherein a shape of the opening of the concave structure is a circle in plan view of the semiconductor stack.
7. The semiconductor light emitting device according to claim 1 , wherein a p-electrode is disposed on a surface of the semiconductor stack opposite to a surface where the concave structure is disposed.
8. The semiconductor light emitting device according to claim 1 , wherein the n-type semiconductor layer includes the concave structure.
9. The semiconductor light emitting device according to claim 1 , wherein the light emitting device further comprising a passivation film comprising an insulating material.