Tunable phosphor for luminescent

• US 8,716,731 B2
• Filed: 04/11/2011
• Issued: 05/06/2014
• Est. Priority Date: 04/11/2011
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: TSMC Solid State Lighting Ltd. (Epistar Corporation)
• Inventors: Yeh, Chiao-Wen, Liu, Ru-Shi
• Primary Examiner(s): Such, Matthew W
• Assistant Examiner(s): Harrison, Monica D
• Application Number:
  US13/084,135
• Publication Number:
  US 20120256212A1
• Time in Patent Office: 1,121 Days
• Field of Search: 257/98, 257/E33.061
• US Class Current: 257/98
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/7728 containing europium
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source

Abstract

The present disclosure provides an illuminating system including a light emitting diode (LED); and a tunable luminescent material disposed approximate the light-emitting diode, wherein the tunable luminescent material includes alkaline earth metal (AE) and silicon aluminum nitride doped by a rare earth element (RE), formulated as (AE)Si_6−pAl_pN₈, wherein p is a parameter defining a relative aluminum content in weight and p is greater than zero.

Claims

1. An illuminating system comprising:

a light emitting diode (LED); and

a tunable luminescent material disposed approximate the light emitting diode, wherein the tunable luminescent material includes alkaline earth metal (AE) and silicon aluminum nitride doped by a rare earth element (RE), formulated as (AE)Si<sub>6−

p</sub>Al_pN₈, wherein p is a parameter defining a relative aluminum content in weight and p is greater than zero, wherein the alkaline earth metal includes strontium (Sr), calcium (Ca), barium (Ba), or a combination thereof, and wherein the tunable luminescent material is formulated as (Sr<sub>1−

x−

y</sub>Ca_xBa_y)<sub>1−

z</sub>Si<sub>6−

p</sub>Al_pN₈;

RE_z; and

parameters x, y, and z are relative composition contents in weight.

2. The illuminating system of claim 1, wherein the parameters x, y, z, and p ranges are 0≦

x≦

1, 0≦

y≦

1, 0.001≦

z≦

0.4, and 0≦

p≦

3, respectively.

3. The illuminating system of claim 2, wherein p is less than or equal to 1.2.

4. The illuminating system of claim 1, wherein the tunable luminescent material is activated by europium (Eu²⁺) and is formulated as (Sr₁₋

x−

yCa_xBa_y)<sub>1−

z</sub>Si<sub>6−

p</sub>Al_pN₈;

Eu²⁺_Z.

5. The illuminating system of claim 1, wherein the tunable luminescent material emits light tunable from red to blue by the parameter p.

6. The illuminating system of claim 1, wherein the light emitting diode includes an emission spectrum with a peak ranging from 440 nm to 650 nm.

7. The illuminating system of claim 1, wherein the tunable luminescent material has an excitation spectrum tunable by the parameter p and the excitation spectrum ranges from about 300 nm to about 500 nm.

8. The illuminating system of claim 1, wherein the tunable luminescent material is embedded in epoxy around the LED.

9. The illuminating system of claim 1, wherein the LED includes an indium gallium nitride (InGaN) LED.

10. A tunable luminescent material comprising:

a rare earth element doped nitridosilicate phosphor formulated as (AE)_zSi<sub>1−

p</sub>Al_pN₈;

RE_z, where AE is one of calcium (Ca), strontium (Sr), barium (Ba), and a combination thereof;

RE is a rare earth element;

z is 0.001≦

z≦

0.4; and

p is 0≦

p≦

3.

11. The tunable luminescent material of claim 10, wherein the rare earth element doped nitridosilicate phosphor includes (Sr₁₋

x−

yCa_xBa_y)<sub>1−

z</sub>Si<sub>6−

p</sub>Al_pN₈;

Eu_z;

x ranges between 0 and 1; and

y ranges between 0 and 1.

12. The tunable luminescent material of claim 10, comprising an excitation spectrum peak ranging from 300 nm to 500 nm.

13. The tunable luminescent material of claim 10, comprising an emission spectrum peak ranging from 440 nm to 650 nm.

14. The tunable luminescent material of claim 10, wherein an emission spectrum and the excitation spectrum of the luminescent material are tunable with an aluminum content of the luminescent material.

15. The tunable luminescent material of claim 10, wherein the luminescent material is embedded in epoxy.

16. A method, comprising:

mixing stoichiometrically powdered strontium nitride (Sr₃N₂), silicon nitride (Si₃N₄), aluminum nitride (AIN), and europium nitride (EuN), thereby forming a mixture free of oxide; and

sintering the mixture under a high pressure and a high temperature, thereby forming a tunable luminescent material having a strontium silicon aluminum nitride.

17. The method of claim 16, wherein the high pressure ranges from about 0.7 MPa to about 1.2 MPa under a nitrogen atmosphere.

18. The method of claim 16, wherein the high temperature ranges between about 1700°

C. and about 2300°

C., and the sintering includes a sintering duration greater than about 0.5 hour.

19. The method of claim 16, wherein the mixing stoichiometrically powdered Sr₃N₂, Si₃N₄, AlN, and EuN includes mixing stoichiometrically powdered Sr₃N₂, calcium nitride (Ca₃N₂), barium nitride (Ba₃N₂), Si₃N₄, AlN, and EuN.

20. The method of claim 16, wherein the mixing stoichiometrically powdered Sr₃N₂, Si₃N₄, AlN, and EuN includes mixing powdered Sr₃N₂, Si₃N₄, and AlN with weights of about 25.45 to about 25.85, about 71.94 to about 60.45, and about 2.19 to about 13.25, respectively.

21. The method of claim 16, further comprising distributing the tunable luminescent material around a light emitting diode (LED).