LIGHT EMITTING DEVICE
This disclosure discloses a light-emitting device. The light-emitting device comprises a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer; a reflective structure formed on the first-type semiconductor layer; and a first interface and a second interface formed between light-emitting stack and the reflective structure; wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface; wherein the reflective structure electrically connects to the first-type semiconductor layer at the first interface, and an area of the first interface is more than an area of the second interface.
1 . A light-emitting device, comprising:
a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer;
a reflective structure formed on the first-type semiconductor layer; and
a first interface and a second interface formed between light-emitting stack and the reflective structure; wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface; wherein the reflective structure electrically connects to the first-type semiconductor layer at the first interface, and an area of the first interface is more than an area of the second interface.
2 . The light-emitting device of claim 1 , wherein the reflective structure comprises a transparent conductive layer, and the first interface is between the first-type semiconductor layer and the transparent conductive layer.
3 . The light-emitting device of claim 1 , wherein the reflective structure comprises a void, and the second interface is between the first-type semiconductor layer and the void.
4 . The light-emitting device of claim 2 , wherein the reflective structure comprises a metal layer contacting the transparent conductive layer.
5 . The light-emitting device of claim 3 , further comprising an electrode on the second-type semiconductor layer, wherein the void has a width larger than a width of the electrode from a cross section view of the light-emitting device.
6 . The light-emitting device of claim 5 , wherein the void is formed at a position corresponding to the electrode.
7 . The light-emitting device of claim 1 , further comprising a bonding structure covering the reflective structure and contacting the first-type semiconductor layer.
8 . A light-emitting device, comprising:
a light-emitting stack having a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer;
a reflective structure formed on the first-type semiconductor layer; and
a first interface and a second interface formed between the light-emitting stack and the reflective structure; wherein the reflective structure comprises a transparent conductive layer and a void formed in the transparent conductive layer, and the first interface is formed between the transparent conductive layer and the first-type semiconductor layer; and
wherein a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface, and the reflective structure electrically connects to the first-type semiconductor layer at the first interface.
9 . The light-emitting device of claim 8 , wherein the reflective structure further comprises a metal layer contacting the transparent conductive layer.
10 . The light-emitting device of claim 8 , wherein the void contains air, N 2 , He, or Ar.
11 . The light-emitting device of claim 8 , wherein the void has a height smaller than 800 Å.
12 . The light-emitting device of claim 8 , further comprising an electrode on the second-type semiconductor layer, wherein the void is at a position corresponding to the electrode.
13 . The light-emitting device of claim 12 , wherein the void has a width larger than a width of the electrode structure from a cross section view of the light-emitting device.
14 . The light-emitting device of claim 8 , wherein the second interface is formed between the void and the first-type semiconductor layer.
15 . A light-emitting device, comprising:
a light-emitting stack comprises a first-type semiconductor layer, a second-type semiconductor layer, and an active layer formed between the first-type semiconductor layer and the second-type semiconductor layer;
a reflective structure formed on the first-type semiconductor layer; and
a bonding structure covering the reflective structure and contacting the first-type semiconductor layer;
wherein the reflective structure electrically connects to the first-type semiconductor layer.
16 . The light-emitting device of claim 15 , wherein a first interface and a second interface formed between the light-emitting stack and the reflective structure, and a critical angle at the first interface for a light emitted from the light-emitting stack is larger than that at the second interface; wherein the reflective structure electrically connects to the first-type semiconductor layer at the first interface.
17 . The light-emitting device of claim 16 , wherein a third interface is formed between the bonding structure and the first-type semiconductor layer, and a critical angle at the third interface for the light emitted from the light-emitting stack is larger than that at the second interface.
18 . The light-emitting device of claim 15 , wherein the bonding structure is between a substrate and the light-emitting stack.
19 . The light-emitting device of claim 15 , wherein the bonding structure comprises a first bonding layer contacting the reflective layer and a second bonding layer devoid of contacting to the reflective layer.
20 . The light-emitting device of claim 15 , wherein the bonding structure comprises metal material.