Thin-film LED with P and N contacts electrically isolated from the substrate

1. A thin-film light emitting diode, comprising:

a substrate;

an insulating dielectric film layer on the substrate;

a reflective electrode disposed on the insulating dielectric film layer via a conductive adhesive layer, wherein the conductive adhesive layer and the reflective electrode comprises metal and together form a metallic current spreading layer; and

an epitaxial structure on the reflective electrode.

2. The thin-film light emitting diode of claim 1 , wherein the substrate is electrically conductive.

3. The thin-film light emitting diode of claim 1 , wherein the substrate is an insulator.

4. The thin-film light emitting diode of claim 1 , wherein the metallic current spreading layer having a thickness greater than about 1 um.

5. The thin-film light emitting diode of claim 1 , wherein the reflective electrode and conductive adhesive layer are recessed from an edge of the thin-film light emitting diode.

6. The thin-film light emitting diode of claim 1 , further comprising a metal layer on a bottom surface of the substrate.

7. The thin-film light emitting diode of claim 1 , further comprising: a second insulating dielectric film layer on a bottom surface of the substrate; and a metal layer on the second insulating dielectric film layer.

8. The thin-film light emitting diode of claim 1 , further comprising a metal contact coupled to the electrode.

9. The thin-film light emitting diode of claim 8 , wherein the metal contact is on the electrode.

10. The thin-film light emitting diode of claim 1 , wherein the substrate is reflective for the wavelength between about 300 nm and 700 nm with a reflectance greater than about 50%.

11. The thin-film light emitting diode of claim 1 , wherein the substrate is transparent for the wavelengths between about 300 nm and 700 nm with a transmittance greater than about 50%.

12. The thin-film light emitting diode of claim 1 , wherein the epitaxial structure comprises a first epitaxial layer, a second epitaxial layer, and an active region between the first epitaxial layer and the second epitaxial layer.

13. The thin film light emitting diode of claim 12 , wherein the first epitaxial layer has a roughened surface with micro-structures, the micro-structures being between about 100 nm and 500 nm in size.

14. The thin-film light emitting diode of claim 12 , wherein the first epitaxial layer is an n-type GaN-based layer and the second epitaxial layer is a p-type GaN-based layer.

15. The thin-film light emitting diode of claim 12 , further comprising a patterned second electrode on the first epitaxial layer.

16. The thin-film light emitting diode of claim 15 , wherein the epitaxial structure is formed to be a mesa on the electrode and the patterned second electrode is on a top surface of the mesa.

17. The thin-film light emitting diode of claim 1 , wherein the substrate is not an original growth substrate for the epitaxial structure.