Light-emitting device having a patterned substrate and the method thereof
View Patent ↗This disclosure provides a light-emitting device including a patterned substrate and the manufacturing method thereof. The patterned substrate has a plurality of depressions and/or extrusions for scattering light emitted from a light-emitting layer. Each of the plurality of depressions and/or extrusions comprises a top portion, a bottom portion, and a sidewall portion enclosing the top portion and the bottom portion, and at least part of the sidewall portion comprises a curve. In a preferred embodiment, the light-emitting device further comprises a rough surface formed on at least one of the top portion, the bottom portion, and the sidewall portion.
1. A light-emitting device, comprising:
a patterned substrate having an uneven surface composed of a plurality of extrusions;
a light-emitting stack overlaying the patterned substrate, comprising a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer;
wherein at least one of the plurality of extrusions comprises a top portion, a bottom portion, and a sidewall portion formed between the top portion and the bottom portion, and wherein a surface roughness of the top portion is larger than a surface roughness of the sidewall portion.
2. The light-emitting device according to claim 1 , wherein each of the top portion and the bottom portion further comprises a rough surface comprising a regular pattern or an irregular pattern.
3. The light-emitting device according to claim 2 , wherein at least part of the sidewall portion comprises a curve.
4. The light-emitting device according to claim 2 , wherein the sidewall portion comprises a plurality of symmetric planes.
5. The light-emitting device according to claim 1 , wherein the substrate comprises sapphire.
6. The light-emitting device according to claim 5 , wherein the bottom portion comprises a sapphire C plane.
7. The light-emitting device according to claim 5 , wherein the sidewall portion comprises at least three symmetric sapphire R planes.
8. The light-emitting device according to claim 1 , wherein the top-view pattern of the extrusion comprises circle or ellipse.
9. The light-emitting device according to claim 1 , wherein the light-emitting stack comprises a III-nitride compound.
10. The light-emitting device according to claim 1 , wherein a ratio of an area of the bottom portion to an area of the top portion is substantially between 0.15 and 0.75.