Light-emitting diode and fabrication method thereof
A light emitting diode includes: a substrate of front and back main surfaces; a V-shaped groove, which has a reflecting surface, formed over front surface of the conductive substrate; a light-emitting epitaxial layer, the margin of which has its vertical projection between the bottom and the inner margin of the V-shaped groove, formed over the substrate, so that light emitted from the light-emitting epitaxial layer margin is incident to the mirror surface of the V-shaped groove and emits outwards. This structure can effectively improve extraction efficiency of device and control path of light at peripheral region of the light-emitting epitaxial layer.
1. A light emitting diode, comprising:
a substrate having front and back main surfaces, and at least one V-shaped groove having a reflecting surface formed over the front main surface of the substrate;
a light-emitting epitaxial layer over the substrate, wherein a peripheral region of the light-emitting epitaxial layer has a vertical projection between a bottom and an inner portion of the V-shaped groove, such that light emitted from the light-emitting epitaxial layer peripheral region is incident upon the reflecting surface of the V-shaped groove and reflected outwards.
2. The light emitting diode of claim 1 , wherein an optical path of the light emitted from the peripheral region of the light-emitting epitaxial layer is adjusted by the V-shaped groove.
3. The light emitting diode of claim 2 , wherein an angle between two side walls of the V-shaped groove is about 90 degrees such that light emitted at a vertical direction is reflected by the V-shaped groove and emits vertically after a parallel displacement outwards.
4. The light emitting diode of claim 3 , wherein: the V-shaped groove has a depth of about 5-20 μm.
5. The light emitting diode of claim 2 wherein an angle between two side walls of the V-shaped groove is an obtuse angle such that light emitted at a vertical direction is reflected by the V-shaped groove and emits outwards, thereby expanding a light emitting angle.
6. The light emitting diode of claim 1 , wherein a reflecting structure is formed between the substrate and the light-emitting epitaxial layer, and wherein a vertical projection of the reflecting structure is at an inner side of the V-shaped groove.
7. The light emitting diode of claim 6 , wherein the reflecting structure is an omni-directional reflector comprising a low-refractivity dielectric layer and a metal reflecting layer.
8. A light-emitting system comprising a plurality of LEDs, each LED including:
a substrate having front and back main surfaces, and at least one V-shaped groove having a reflecting surface formed over the front main surface of the substrate;
a light-emitting epitaxial layer over the substrate, wherein a peripheral region of the light-emitting epitaxial layer has a vertical projection between a bottom and an inner portion of the V-shaped groove, such that light emitted from the light-emitting epitaxial layer peripheral region is incident upon the reflecting surface of the V-shaped groove and reflected outwards.
9. The system of claim 8 , wherein an optical path of the light emitted from the peripheral region of the light-emitting epitaxial layer is adjusted by the V-shaped groove.
10. The system of claim 9 , wherein an angle between two side walls of the V-shaped groove is about 90 degrees such that light emitted at a vertical direction is reflected by the V-shaped groove and emits vertically after a parallel displacement outwards.
11. The system of claim 10 , wherein: the V-shaped groove has a depth of about 5-20 μm.
12. The system of claim 8 wherein an angle between two side walls of the V-shaped groove is an obtuse angle such that light emitted at a vertical direction is reflected by the V-shaped groove and emits outwards, thereby expanding a light emitting angle.
13. The system of claim 12 , wherein a reflecting structure is formed between the substrate and the light-emitting epitaxial layer, and wherein a vertical projection of the reflecting structure is at an inner side of the V-shaped groove.
14. The system of claim 13 , wherein the reflecting structure is an omni-directional reflector comprising a low-refractivity dielectric layer and a metal reflecting layer.