Light emitting device with reflective electrode
View Patent ↗A light-emitting device includes a semiconductor light emitting stack and an electrode on the semiconductor light emitting stack, wherein the electrode includes a mirror layer, an adhesion layer inserted between the mirror layer and the semiconductor light emitting stack, a bonding layer, and a barrier layer inserted between the mirror layer and the bonding layer and covering the mirror layer to prevent the mirror layer from reacting with the bonding layer, wherein the barrier layer includes a first pair of different metals.
1. A light-emitting device, comprising:
a semiconductor light emitting stack;
an electrode on the semiconductor light emitting stack, the electrode comprising a mirror layer, an adhesion layer inserted between the mirror layer and the semiconductor light emitting stack, a bonding layer, and a barrier layer inserted between the mirror layer and the bonding layer and covering the mirror layer to prevent the mirror layer from reacting with the bonding layer; and
a plurality of pits between the electrode and the semiconductor light emitting stack,
wherein the barrier layer comprises a first pair of metal layers and a second pair of metal layers, and the adhesion layer is electrically conductive and has a thickness smaller than or equal to 30 Å, and one of the plurality of pits is not filled up by the adhesion layer and the mirror layer.
2. The light-emitting device according to claim 1 , wherein the semiconductor light emitting stack comprises a first semiconductor layer, a second semiconductor layer and an active layer between the first semiconductor layer and the second semiconductor layer, and the electrode ohmically contacts the first semiconductor layer or the second semiconductor layer.
3. The light-emitting device according to claim 1 , wherein the first pair of metal layers comprises a first metal layer and a second metal layer, and the adhesion between the first metal layer and the mirror layer is higher than the adhesion between the second metal layer and the mirror layer.
4. The light-emitting device according to claim 3 , wherein the first metal layer is easier to react with the mirror layer than the second metal layer is.
5. The light-emitting device according to claim 1 , wherein the second pair of metal layers comprises a third metal layer and a fourth metal layer, and the adhesion between the third metal layer and the mirror layer is lower than the adhesion between the fourth metal layer and the mirror layer.
6. The light-emitting device according to claim 5 , wherein the third metal layer is easier to react with the mirror layer than the fourth metal layer.
7. The light-emitting device according to claim 1 , wherein the first pair of metal layers or the second pair of metal layers comprises any two of Cr, Pt, Ti, TiW, and Ni.
8. The light-emitting device according to claim 1 , wherein a total thickness of the first pair of metal layers or the second pair of metal layers is greater than or equal to 400 Å.
9. The light-emitting device according to claim 1 , wherein the barrier layer fully covers the mirror layer to prevent the mirror layer from contacting the bonding layer.
10. The light-emitting device according to claim 1 , wherein the barrier layer comprises a first surface contacting the bonding layer and a second surface contacting the mirror layer, and the first surface is more even than the second surface.
11. The light-emitting device according to claim 1 , wherein a thickness of the mirror layer is greater than or equal to 1000 Å.
12. The light-emitting device according to claim 1 , wherein a reflectivity of the mirror layer is greater than or equal to 70% for a light emitted from the semiconductor light emitting stack.
13. The light-emitting device according to claim 1 , wherein a material of the mirror layer comprises Al or Ag.
14. The light-emitting device according to claim 1 , wherein the adhesion layer comprises Cr or Rh.
15. The light-emitting device according to claim 1 , wherein the thickness of the adhesion layer is smaller than or equal to 5 Å.
16. The light-emitting device according to claim 1 , wherein the adhesion layer is discontinuous and comprises a plurality of adhesion regions.
17. The light-emitting device according to claim 1 , wherein the bonding layer fully covers the barrier layer.
18. The light-emitting device according to claim 1 , wherein the second pair of metal layers fully covers the first pair of metal layers.
19. The light-emitting device according to claim 1 , wherein the plurality of pits is filled up by the barrier layer.
20. The light-emitting device according to claim 1 , further comprising a transparent conductive layer, wherein a top surface of the transparent conductive layer comprises the plurality of pits.