Light emitting devices with improved light extraction efficiency
View Patent ↗A device includes a light emitting semiconductor device bonded to an optical element. In some embodiments, the optical element may be elongated or shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element. In some embodiments, the semiconductor light emitting device and optical element are positioned in a reflector or adjacent to a light guide. The optical element may be bonded to the first semiconductor light emitting device by a bond at an interface disposed between the optical element and the semiconductor light emitting device. In some embodiments, the bond is substantially free of organic-based adhesives.
1. A device comprising:
a semiconductor light emitting device comprising a stack of semiconductor layers including an active region; and
an optical element bonded to the semiconductor light emitting device by a bond disposed at an interface between the optical element and the semiconductor light emitting device;
wherein the optical element is shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element.
2. The device of claim 1 wherein the optical element comprises a wedge comprising:
a first surface adjacent to the bond connecting the optical element to the semiconductor light emitting device;
a substantially flat second surface substantially perpendicular to the first surface; and
a substantially flat third surface connecting the first and second surfaces.
3. The device of claim 2 further comprising a mirror adjacent to at least a portion of the third surface.
4. The device of claim 1 wherein the optical element comprises:
a first surface adjacent to the bond connecting the optical element to the semiconductor light emitting device;
a substantially flat second surface substantially perpendicular to the first surface; and
a curved third surface.
5. The device of claim 4 further comprising a mirror adjacent to at least a portion of the third surface.
6. The device of claim 4 wherein the curved third surface connects the first and second surface.
7. The device of claim 4 wherein the curved third surface curves downward from the second surface toward a point on a central axis of the optical element and semiconductor light emitting device.
8. The device of claim 1 wherein a cross section of the optical element is thinner in a central region than in a peripheral region.
9. The device of claim 1 wherein a surface of the optical element comprises a reflector.
10. The device of claim 9 wherein the reflector is selected from the group of a metallization, a dielectric layer, a reflective coating, and a total internal reflector.
11. The device of claim 1 wherein said bond is substantially free of organic-based adhesive.
12. The device of claim 1 wherein the optical element is elongated.
13. The device of claim 12 wherein the optical element comprises a rectangular slab.
14. The device of claim 1 wherein said bond comprises a bonding layer.
15. The device of claim 1 wherein the optical element is directly bonded to a surface of the semiconductor light emitting device.
16. The device of claim 1 wherein the semiconductor light emitting device comprises a substrate, wherein a surface of the semiconductor light emitting device bonded to the optical element is a surface of the substrate.
17. The device of claim 1 wherein the semiconductor light emitting device comprises a metal contact, wherein a surface of the semiconductor light emitting device bonded to the optical element is a surface of the metal contact.
18. The device of claim 1 wherein a surface of the semiconductor light emitting device bonded to the optical element is a surface of the stack of semiconductor layers.