Method for making a light-emitting device
View Patent ↗This disclosure discloses a method for making a light-emitting device, comprising steps of: providing a substrate; forming a light-emitting stack on the substrate; forming a first layer on the light-emitting stack; providing a permanent substrate; forming a second layer on the permanent substrate; bonding the first layer and the second layer to form a bonding layer to connect the substrate and the permanent substrate; wherein a refractive index of the bonding layer decreases from the light-emitting stack toward the permanent substrate.
1. A method for making a light-emitting device, comprising steps of:
providing a substrate;
forming a light-emitting stack on the substrate;
forming a first layer on the light-emitting stack;
providing a permanent substrate;
forming a second layer on the permanent substrate; and
bonding the first layer and the second layer to connect the substrate and the permanent substrate;
wherein a refractive index of the second layer decreases from the light-emitting stack toward the permanent substrate, and
wherein the second layer comprises an intermediate layer on the permanent substrate and a semiconductor optical layer on the intermediate layer, and a refractive index of the intermediate layer is between a refractive index of the permanent substrate and a refractive index of the semiconductor optical layer.
2. The method according to claim 1 , wherein the second layer further comprises a nucleation layer between the semiconductor optical layer and the intermediate layer.
3. The method according to claim 2 , wherein the nucleation layer and the semiconductor optical layer are formed under different temperature.
4. The method according to claim 3 , wherein the nucleation layer is formed at a temperature lower than a temperature of forming the semiconductor optical layer.
5. The method according to claim 3 , wherein the nucleation layer is formed at a temperature between 300˜550° C.
6. The method according to claim 3 , wherein the semiconductor optical layer is formed at a temperature between 600˜800° C.
7. The method according to claim 2 , wherein a thickness of the semiconductor optical layer is greater than a thickness of the nucleation layer.
8. The method according to claim 2 , wherein the nucleation layer has a refractive index ranging from 2.4 to 3.4.
9. The method according to claim 1 , wherein the first layer has a refractive index greater than a refractive index of the intermediate layer.
10. The method according to claim 1 , wherein the refractive index of the intermediate layer ranges from 1.7 to 3.4.
11. The method according to claim 1 , wherein the semiconductor optical layer has a refractive index ranging from 2.4 to 3.4.
12. The method according to claim 1 , wherein the permanent substrate is transparent.
13. The method according to claim 1 , wherein the permanent substrate comprises glass, sapphire, or quartz.
14. The method according to claim 1 , wherein the permanent substrate has a surface with a patterned portion.
15. The method according to claim 1 , wherein the light-emitting stack comprises GaN based material.
16. The method according to claim 1 , further comprising a step of forming a reflective layer on a side of the permanent substrate opposing to a side connected to the light-emitting stack.
17. The method according to claim 1 , further comprising a step of removing the substrate from the light-emitting stack after the step of bonding the first layer and the second layer.
18. The method according to claim 1 , wherein the light-emitting device further comprises a bonding interface between the first layer and the second layer after the step of bonding the first layer and the second layer.
19. The method according to claim 1 , further comprising a step of performing a surface treatment on the first layer and on the second layer before the step of bonding the first layer and the second layer.