Reflective structure for light emitting devices

• US 10,665,759 B2
• Filed: 09/25/2017
• Issued: 05/26/2020
• Est. Priority Date: 09/27/2016
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Inventors: Nelson, Erik C., Deb, Parijat P.
• Primary Examiner(s): Anya, Igwe U
• Application Number:
  US15/714,613
• Publication Number:
  US 20180090645A1
• Time in Patent Office: 974 Days
• Field of Search: 257 98
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil

Abstract

Described is a reflector for light emitting devices. A device includes a reflector in contact with a first n-type region and a second n-type region. The reflector includes multiple layers. One layer having an index of refraction different than the other layers. The device includes a light emitting region (LER) in contact with the second n-type region, a p-type region in contact with the LER and a light extraction region (LXR) in contact with the p-type region. A majority of light escapes the device through the LXR. The reflector reflects light emitted by the LER back towards the LXR. In another device, a reflector is embedded in a n-type region of the device. The device includes a LER, a p-type region, and a wavelength converter structure. The reflector reflects light emitted by the wavelength converting structure back towards the wavelength converting structure.

Claims

1. A device comprising:

a n-type region;

a reflector embedded in the n-type region, the reflector including a plurality of layers and at least one layer of the plurality of layers having an index of refraction different than other layers of the plurality of layers;

a light emitting region in contact with the n-type region;

a p-type region in contact with the light emitting region; and

a wavelength converting structure in contact with the n-type region and configured to absorb light emitted by the light emitting region and in response emit light of a longer wavelength;

the plurality of layers in the reflector arranged and configured to transmit light emitted by the light emitting region into the wavelength converting structure and to reflect longer wavelength light emitted by the wavelength converting structure toward the n-type region back toward the wavelength converting structure.

2. The device of claim 1, wherein the at least one layer is a first plurality of layers alternating with a second plurality of layers of the plurality of layers, the first plurality of layers being more porous than the second plurality of layers.

3. The device of claim 1, wherein at the least one layer is more highly doped than the other plurality of layers.

4. The device of claim 1, wherein the at least one layer is a porous semiconductor layer and the other plurality of layers are non-porous semiconductor layers.

5. The device of claim 1, wherein the at least one layer is GaN and the other layers are AlInN.

6. The device of claim 1, wherein the at least one layer is InGaN and the other layers are AlGaN.

7. The device of claim 1, wherein the at least one layer is a first plurality of layers alternating with a second plurality of layers of the plurality of layers, the first plurality of layers each having a first index of refraction, and the second plurality of layers each have a second index of refraction different from the first index of refraction.

8. The device of claim 7, wherein the first plurality of layers have a first composition, and the second plurality of layers have a second composition different from the first composition.

9. The device of claim 7, wherein the first plurality of layers has a first porosity, and the second plurality of layers has a second porosity different from the first porosity.

10. The device of claim 7, wherein the first plurality of layers has a first n-type dopant concentration, and the second plurality of layers has a second n-type dopant concentration different from the first n-type doping concentration.