Thin-film LED with P and N contacts electrically isolated from the substrate
View Patent ↗A thin-film LED includes an insulating substrate, an electrode on the insulating substrate, and an epitaxial structure on the electrode.
1. A thin-film light emitting diode, comprising:
an insulating substrate;
a conductive adhesive disposed directly on the insulating substrate;
a reflective metal electrode disposed directly on the conductive adhesive, wherein the conductive adhesive layer is metal and with the metal electrode together form a metallic current spreading layer, the metallic current spreading layer having a thickness greater than about 1 um; and
a single epitaxial structure on the electrode.
2. The thin-film light emitting diode of claim 1 , further comprising a metal layer on a bottom surface of the insulating substrate.
3. The thin-film light emitting diode of claim 1 , further comprising a metal contact coupled to the metal electrode.
4. The thin-film light emitting diode of claim 3 , wherein the metal contact is on the metal electrode.
5. The thin-film light emitting diode of claim 1 , wherein the insulating substrate is transparent for the wavelengths between about 300 nm and 700 nm with a transmittance greater than about 50%.
6. The thin-film light emitting diode of claim 1 , wherein the insulating substrate is reflective for the wavelength between about 300 nm and 700 nm with a reflectance greater than about 50%.
7. 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.
8. The thin film light emitting diode of claim 7 , 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.
9. The thin-film light emitting diode of claim 7 , wherein the first epitaxial layer is an n-type GaN-based layer and the second epitaxial layer is a p-type GaN-based layer.
10. The thin-film light emitting diode of claim 7 , further comprising a patterned second electrode is on the first epitaxial layer.
11. The thin-film light emitting diode of claim 10 , 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.
12. The thin-film light emitting diode of claim 1 , wherein the insulating substrate is not an original growth substrate for the epitaxial structure.