LIGHT-EMITTING ELEMENT

1 . A light-emitting element, including:

a substrate including an upper surface;

a plurality of protrusions formed on the upper surface, wherein the plurality of protrusions includes a height less than or equal to 1 μm; and

a stack structure formed on the substrate, wherein the stack structure includes a first doped semiconductor layer, a light-emitting layer, and a second doped semiconductor layer, wherein the stack structure includes a total thickness less than 4 μm.

2 . The light-emitting element in accordance with claim 1 , wherein the substrate includes a sapphire substrate.

3 . The light-emitting element in accordance with claim 1 , wherein the plurality of protrusions includes a cone shape.

4 . The light-emitting element in accordance with claim 1 , wherein the height is between 0.65 μm˜0.95 μm.

5 . The light-emitting element in accordance with claim 3 , wherein the plurality of protrusions includes a width between 0.6 μm˜1.6 μm.

6 . The light-emitting element in accordance with claim 3 , wherein the plurality of protrusions includes an aspect ratio between 0.55˜0.85.

7 . The light-emitting element in accordance with claim 3 , wherein a distance between the plurality of protrusions is between 0.1 μm˜0.3 μm.

8 . The light-emitting element in accordance with claim 3 , wherein a distance between the plurality of protrusions is between 0.6 μm˜1.6 μm.

9 . The light-emitting element in accordance with claim 3 , wherein a ratio of an area of the substrate not occupied by the plurality of protrusions to an area of the plurality of protrusions is greater than 35%.

10 . The light-emitting element in accordance with claim 1 , further including a buffer layer including aluminum oxynitride conformably formed on the upper surface of the substrate and the plurality of protrusions.

11 . The light-emitting element in accordance with claim 10 , wherein a ratio of an aluminum content to a nitrogen content of the buffer layer is between 0.45˜0.9.

12 . The light-emitting element in accordance with claim 10 , wherein a difference between an aluminum content of the buffer layer on a sidewall of the plurality of protrusions and an aluminum content of the buffer layer on the upper surface of the substrate is less than 5%.

13 . The light-emitting element in accordance with claim 10 , wherein a difference between an aluminum content of the buffer layer on a sidewall of the plurality of protrusions and an aluminum content of the buffer layer on the upper surface of the substrate is greater than 5% but less than 12%.

14 . The light-emitting element in accordance with claim 11 , wherein the buffer layer includes a thickness between 15 nm and 25 nm.

15 . The light-emitting element in accordance with claim 11 , wherein a thickness of the buffer layer on a sidewall of the plurality of protrusions is smaller than a thickness of the buffer layer on the upper surface of the substrate.

16 . The light-emitting element in accordance with claim 1 , wherein the stack structure further includes an undoped semiconductor layer formed between the substrate and the first doped semiconductor layer, and a thickness of the first doped semiconductor layer and a thickness of the undoped semiconductor layer include a ratio between 0.9˜1.1.

17 . The light-emitting element in accordance with claim 1 , wherein the stack structure further includes an undoped semiconductor layer formed between the substrate and the first doped semiconductor layer, and the undoped semiconductor layer includes a thickness less than 2 μm.

18 . The light-emitting element in accordance with claim 1 , wherein the undoped semiconductor layer includes a thickness 1.5 μm thicker than the height of the plurality of protrusions.

19 . The light-emitting element in accordance with claim 1 , the light-emitting element includes a total thickness less than 110 μm.

20 . The light-emitting element in accordance with claim 19 , wherein the total thickness is between 70 μm˜90 μm.