Light-emitting device with patterned current diffusion layer
View Patent ↗Disclosed is a light-emitting device including a permanent substrate, an adhesive layer on the permanent substrate, a current diffusion layer on the adhesive layer, and a semiconductor stack layer on the current diffusion layer. The current diffusion layer has an etched portion and an unetched portion, wherein the etched and unetched portions have a horizontal height difference. The horizontal height difference and the current diffusion layer thickness have a ratio of 20:100 to 70:100.
1. A light-emitting device, comprising:
a permanent substrate;
an adhesive layer on the permanent substrate;
a current diffusion layer on the adhesive layer, wherein the current diffusion layer has an etched portion and an unetched portion;
a semiconductor stack layer on the current diffusion layer, comprising:
a second type semiconductor layer on the current diffusion layer;
an active layer on the second type semiconductor layer; and
a first type semiconductor layer on the active layer, wherein the first type semiconductor layer and the second type semiconductor layer have different electrical properties; and
a middle layer between the current diffusion layer and the semiconductor stack layer, wherein the difference between a thickness of the etched portion and a thickness of the unetched portion is about 20% to 70% of the thickness of the unetched portion of the current diffusion layer.
2. The light-emitting device as claimed in claim 1 , wherein the permanent substrate is a transparent insulation substrate.
3. The light-emitting layer as claimed in claim 2 , wherein the adhesive layer is a transparent adhesive layer.
4. The light-emitting device as claimed in claim 1 , wherein the permanent substrate is an opaque insulation substrate.
5. The light-emitting layer as claimed in claim 4 , wherein the adhesive layer is a metal adhesive layer.
6. The light-emitting layer as claimed in claim 4 , further comprising a reflection layer between the permanent substrate and the adhesive layer.
7. The light-emitting layer as claimed in claim 1 , wherein the current diffusion layer has a doping concentration greater than or equal to 5×10 17 /cm 3 .
8. The light-emitting layer as claimed in claim 1 , wherein the current diffusion layer is doped by Mg or Zn.
9. The light-emitting device as claimed in claim 1 , wherein a ratio of the doping concentration of the middle layer to the doping concentration of the current diffusion layer is less than or equal to 1:3.
10. The light-emitting layer as claimed in claim 1 , wherein the middle layer is doped by Mg or Zn.
11. The light-emitting device as claimed in claim 1 , wherein the band gap of the current diffusion layer is greater than the band gap of any layer in the semiconductor stack layer.
12. The light-emitting device as claimed in claim 1 , wherein the current diffusion layer comprises GaP or ZnO.
13. The light-emitting device as claimed in claim 1 , wherein the middle layer comprises GaP or ZnO.
14. The light-emitting device as claimed in claim 1 , wherein the current diffusion layer has a thickness greater than or equal to 4 μm.
15. The light-emitting device as claimed in claim 1 , wherein the current diffusion layer has a rough top surface and/or a rough bottom surface.
16. The light-emitting device as claimed in claim 5 , wherein the metal adhesive layer is selected form the group consisting of Au, Au—Sn, Sn, In, Au—Ag, and Pb—Sn.