Light-emitting device having a patterned substrate and the method thereof
A light-emitting device comprises a textured substrate comprising a plurality of textured structures, wherein the textured structures and the textured substrate are both composed of sapphire; and a light-emitting stack overlaying the textured substrate, comprising a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer, wherein each of the plurality of textured structures comprises a top portion having a first top-view shape, and a bottom portion parallel to the top portion and having a second top-view shape, wherein the first top-view shape comprises a circle or an ellipse, the first top-view shape comprises a first periphery and the second top-view shape comprises a second periphery, the first periphery is enclosed by the second periphery, and various distances are between each of the first periphery and the second periphery.
1. A light-emitting device, comprising:
a sapphire substrate comprising a flat surface, a lower surface, and a plurality of depressions between the flat surface and the lower surface;
a semiconductor buffer layer filled the plurality of depressions and formed on the flat surface; and
a light-emitting stack comprising III-V semiconductor, overlaying the semiconductor buffer layer, comprising a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer,
wherein in a plan view of the light-emitting device, one of the plurality of depressions comprises an opening top portion having a first top-view shape and a bottom portion having a second top-view shape,
wherein in a cross-sectional view of the light-emitting device, the one of the plurality of depressions comprises a sidewall portion connecting the opening top portion and the bottom portion, and
wherein in a cross-sectional view of the light-emitting device, the sidewall portion near the opening top portion or the bottom portion is a curve.
2. The light-emitting device according to claim 1 , wherein the opening top portion is closer to the light-emitting stack than the bottom portion to the light-emitting stack.
3. The light-emitting device according to claim 1 , wherein the first top-view shape is different from the second top-view shape.
4. The light-emitting device according to claim 1 , wherein the first top-view shape comprises a circle or an ellipse.
5. The light-emitting device according to claim 1 , wherein the second top-view shape comprises a triangle.
6. The light-emitting device according to claim 1 , wherein the semiconductor buffer layer comprises Ill-nitride materials.
7. The light-emitting device according to claim 6 , wherein the semiconductor buffer layer comprises AN.
8. The light-emitting device according to claim 1 , wherein the sidewall portion comprises three symmetric planes.
9. The light-emitting device according to claim 1 , wherein the bottom portion comprises an area smaller than an area of the opening top portion.
10. The light-emitting device according to claim 1 , wherein the bottom portion is flat.
11. A light-emitting device, comprising:
a sapphire substrate comprising a flat surface, a lower surface, and a plurality of depressions between the flat surface and the lower surface;
a semiconductor buffer layer filled the plurality of depressions and formed on the flat surface; and
a light-emitting stack comprising III-V semiconductor, overlaying the semiconductor buffer layer, comprising a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer,
wherein in a plan view of the light-emitting device, one of the plurality of depressions comprises an opening top portion having a top-view shape,
wherein in a cross-sectional view of the light-emitting device, the one of the plurality of depressions comprises a plurality of sidewall planes intersected at a bottom point, and
wherein in a cross-sectional view of the light-emitting device, the sidewall portion near the opening top portion or the bottom portion is a curve.
12. The light-emitting device according to claim 11 , wherein the opening top portion is closer to the light-emitting stack than the bottom point to the light-emitting stack.
13. The light-emitting device according to claim 11 , wherein the top-view shape comprises a circle or an ellipse.
14. The light-emitting device according to claim 11 , wherein the semiconductor buffer layer comprises Ill-nitride materials.
15. The light-emitting device according to claim 14 , wherein the semiconductor buffer layer comprises AlN.
16. The light-emitting device according to claim 11 , wherein the plurality of sidewall planes comprises sapphire R plane.
17. The light-emitting device according to claim 11 , wherein the flat surface comprises sapphire C plane.