WAVELENGTH-CONVERTED SEMICONDUCTOR LIGHT EMITTING DEVICE INCLUDING A FILTER AND A SCATTERING STRUCTURE

• US 20110012147A1
• Filed: 07/15/2009
• Published: 01/20/2011
• Est. Priority Date: 07/15/2009
• Status: Abandoned Application

• Current Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.), Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.), Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Krames, Michael R., Bierhuizen, Serge J.
• Application Number:
  US12/503,506
• Publication Number:
  US 20110012147A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 2215/0567 Solid-state light source, e.g. LED, laser
• CPC Class Codes: G03B 2215/0592 installed in front of light emitter
• 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 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/50 Wavelength conversion elements

Abstract

A semiconductor structure comprises a light emitting layer disposed between an n-type region and a p-type region. A wavelength converting material is disposed over the semiconductor structure. The wavelength converting material is configured to absorb light emitted by the semiconductor structure and emit light of a different wavelength. A filter configured to reflect blue ambient light is disposed over the wavelength converting material. A scattering structure is disposed over the wavelength converting layer. The scattering structure is configured to scatter light. In some embodiments, the scattering structure is a transparent material having a rough surface, containing non-wavelength-converting particles that appear substantially white in ambient light, or including both a rough surface and white particles.

Claims

1. A device comprising:

a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region;

a wavelength converting material disposed over the semiconductor structure, wherein the wavelength converting material is configured to absorb light emitted by the semiconductor structure and emit light of a different wavelength;

a filter disposed over the wavelength converting material, wherein the filter is configured to reflect at least a portion of blue ambient light; and

a scattering structure disposed over the wavelength converting layer, wherein the scattering structure is configured to scatter light.

2. The device of claim 1 wherein the scattering structure is a transparent material containing non-wavelength-converting particles that appear substantially white in ambient light.

3. The device of claim 2 wherein the particles comprise TiO₂.

4. The device of claim 2 wherein the particles comprise one of TiO_x, Al_xO_y, Al₂O₃, ZrO_x, and ZrO₂.

5. The device of claim 2 wherein the transparent material comprises silicone.

6. The device of claim 2 wherein the transparent material comprises one of epoxy, silres, and sol gel.

7. The device of claim 2 wherein the particles have an average diameter less than one micron.

8. The device of claim 2 wherein the particles comprise between 1% and 7% of the encapsulant.

9. The device of claim 1 wherein the scattering structure is a transparent material with a rough top surface.

10. The device of claim 9 wherein a top surface of the scattering structure has a roughness parameter Ra of at least 40 Å

rms.

11. The device of claim 1 wherein the light emitting layer is a III-nitride layer configured to emit blue light when forward biased.

12. The device of claim 1 wherein the wavelength converting material is a ceramic phosphor.

13. The device of claim 1 wherein the wavelength converting material is configured to emit yellow light.

14. The device of claim 1 wherein the filter is a dichroic filter.

15. The device of claim 1 wherein the scattering structure is configured such that at least 10% of a quantity of collimated light incident on the scattering structure at 0°

relative to a normal to a top surface of the filter is scattered into angles between 5° and

85°

relative to a normal to a top surface of the filter.