Light-emitting device and manufacturing method thereof

1. An LED manufacturing method comprising steps of:

providing a substrate comprising a first surface;

forming a first portion of a first semiconductor layer on the first surface in a reaction chamber in a first atmosphere comprising a first carrier gas; and

forming a second portion of the first semiconductor layer on the first portion in the reaction chamber in a second atmosphere comprising a second carrier gas;

wherein a plurality of first cavities is formed on a surface of the first portion during forming the first portion; and

wherein the plurality of first cavities is transformed to a plurality of second cavities during forming the second portion, and one of the second cavities comprises a first inclined surface and a second inclined surface above the first inclined surface.

2. The LED manufacturing method according to claim 1 , wherein the first inclined surface has a larger slope than the second inclined surface.

3. The LED manufacturing method according to claim 1 , wherein the first carrier gas is N 2 , and the second carrier gas is H 2 , and wherein the first atmosphere is devoid of the second carrier gas, and the second atmosphere is devoid of the first carrier gas.

4. The LED manufacturing method according to claim 1 , wherein the first atmosphere

comprises the first carrier gas and the second carrier gas, and a gas flow rate of the first carrier gas is higher than that of the second carrier gas.

5. The LED manufacturing method according to claim 4 , wherein the first carrier gas is N 2 , and the second carrier gas is H 2 .

6. The LED manufacturing method according to claim 1 , wherein the second atmosphere comprises the first carrier gas and the second carrier gas, and a gas flow rate of the second carrier gas is higher than that of the first carrier gas.

7. The LED manufacturing method according to claim 6 , wherein the first carrier gas is N 2 , and the second carrier gas is H 2 .

8. The LED manufacturing method according to claim 1 , wherein one of the first cavity is etched by the second carrier gas to form the first inclined surface and the second inclined surface.

9. The LED manufacturing method according to claim 1 , wherein each of the second cavities comprises a hexagonal form in a top view.

10. The LED manufacturing method according to claim 1 , before forming the first semiconductor layer, further comprising steps of: forming a second semiconductor layer on the first surface of the substrate; and forming a light-emitting layer on the second semiconductor layer.

11. The LED manufacturing method according to claim 10 , wherein the substrate is placed in a MOCVD reaction chamber, and the second carrier gas, a first precursor, a second precursor and a third precursor are introduced into the MOCVD reaction chamber, wherein the first precursor comprises a Group III element, the second precursor comprises a Group V element and the third precursor comprises an n-type dopant, wherein the second carrier gas moves the first, second, and third precursors to deposit the second semiconductor layer on the first surface.

12. The LED manufacturing method according to claim 11 , wherein the Group III element comprises Ga or Al.

13. The LED manufacturing method according to claim 11 , after the second semiconductor layer is formed, the first carrier gas, the first precursor, the second precursor and the third precursor are introduced into the MOCVD reaction chamber, wherein the first carrier gas moves the first, second, and third precursors to deposit the light-emitting layer on the second semiconductor layer.

14. The LED manufacturing method according to claim 13 , wherein the Group III element comprises Ga or Al.

15. The LED manufacturing method according to claim 10 , wherein the substrate is placed in a MOCVD reaction chamber, and after the light-emitting layer is formed, the first carrier gas, a first precursor, a second precursor and a third precursor are introduced into the MOCVD reaction chamber, wherein the first precursor comprises a Group III element, the second precursor comprises a Group V element and the third precursor comprises a p-type dopant, wherein the first carrier gas moves the first, second, and third precursors to deposit the first portion on the light-emitting layer.

16. The LED manufacturing method according to claim 15 , after the first portion is formed, the second carrier gas, the first precursor, the second precursor and the third precursor are introduced into the MOCVD reaction chamber, wherein the second carrier gas moves the first, second, and third precursors to deposit the second portion on the first portion.

17. The LED manufacturing method according to claim 15 , wherein the Group III element comprises Ga or Al.

18. The LED manufacturing method according to claim 16 , wherein the Group III element comprises Ga or Al.

19. The LED manufacturing method according to claim 10 , before forming the second semiconductor layer, further comprising a step of: forming a buffer layer on the first surface of the substrate.

20. The LED manufacturing method according to claim 1 , wherein a vertical height corresponding to the first inclined surface is H 1 , and a vertical height corresponding to the second inclined surface is H 2 , and 1.5≦H 1 /H 2 ≦2.

21. The LED manufacturing method according to claim 1 , wherein each of the second cavities comprises a deepest point, and at least two of the second cavities have different distances from the deepest point to the first surface.

22. The LED manufacturing method according to claim 1 , wherein the reaction chamber is a MOCVD reaction chamber.

23. The LED manufacturing method according to claim 1 , wherein the first semiconductor layer further comprises a top surface substantially parallel to the first surface, and the second inclined surface is directly connected to the first inclined surface and the top surface.