Phosphor converted light emitting device
View Patent ↗A phosphor converted light emitting device includes a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region, the light emitting layer being configured to emit light having a first peak wavelength; a first phosphor configured to emit light having a second peak wavelength; and a second phosphor configured to emit light having a third peak wavelength. The second phosphor is an Eu 3+ -activated phosphor, configured such that in the excitation spectrum at 298K and 1.013 bar, a maximum intensity in a wavelength range between 460 nm and 470 nm is at least 5% of a maximum intensity in a wavelength range between 220 nm to 320 nm.
1. A device comprising:
a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region, the light emitting layer being configured to emit light having a first peak wavelength;
a first phosphor disposed in a path of light emitted by the light emitting layer, the first phosphor being configured to emit light having a second peak wavelength; and
a second phosphor disposed in a path of light emitted by the light emitting layer, the second phosphor being configured to emit light having a third peak wavelength, wherein:
the second phosphor comprises Eu 3+ ; and
in the excitation spectrum of the second phosphor at 298K and 1.013 bar, a maximum intensity in a wavelength range between 460 nm and 470 nm is at least 5% of a maximum intensity in a wavelength range between 220 nm to 320 nm.
2. The device of claim 1 wherein the semiconductor structure comprises a III-nitride structure.
3. The device of claim 1 wherein:
the first peak wavelength is blue;
the second peak wavelength is yellow or green; and
the third peak wavelength is red.
4. The device of claim 1 wherein the third peak wavelength is longer than the second peak wavelength.
5. The device of claim 1 wherein the first phosphor is formed over the semiconductor structure and the second phosphor is formed over the first phosphor.
6. The device of claim 1 wherein the first phosphor is disposed in a ceramic member.
7. The device of claim 6 wherein the second phosphor comprises a plurality of particles disposed in a transparent material disposed over the ceramic member.
8. The device of claim 6 wherein:
the ceramic member is a first ceramic member; and
the second phosphor is disposed in a second ceramic member.
9. The device of claim 8 wherein:
the second ceramic member is disposed over the first ceramic member; and
the first and second ceramic members are connected by an adhesive.
10. The device of claim 1 wherein the first phosphor is a conformal layer disposed over a top and a side surface of the semiconductor structure.
11. The device of claim 10 wherein the second phosphor comprises a plurality of particles disposed in a transparent material disposed over the conformal layer.
12. The device of claim 1 wherein the first phosphor is one of (Lu 1-x-y-a-b Y x Gd y ) 3 (Al 1-z Ga z ) 5 O 12 :Ce a Pr b wherein 0<x<1, 0<y<1, 0<z≦0.1, 0<a≦0.2 and 0<b≦0.1; Lu 3 Al 5 O 12 :Ce 3+ ; Y 3 Al 5 O 12 :Ce 3+ ; SrSi 2 N 2 O 2 :Eu 2+ ; (Sr 1-u-v-x Mg u Ca v Ba x )(Ga 2-y-z Al y In z S 4 ):Eu 2+ ; SrGa 2 S 4 :Eu 2+ ; and Sr 1-x Ba x SiO 4 :Eu 2+ .
13. The of claim 1 wherein in an emission spectrum of the second phosphor at 298 K and 1.013 bar, a peak area in a wavelength range between 680 nm and 720 nm is at least 15% of a peak area in a wavelength range between 570 nm and 720 nm.
14. The device of claim 1 wherein an atomic dopant level of Eu in the second phosphor material is less than or equal to 20%.
15. The device of claim 1 wherein the second phosphor further comprises a co-dopant comprising one of Bi, In, Tl, Sb, and mixtures thereof.
16. The device of claim 15 wherein a ratio in atom % of Eu:codopant in the second phosphor material is between 0.1:1 and 10:1.
17. The device of claim 1 wherein the second phosphor is selected from a group comprising oxides, oxyhalogenides, garnets, vanadates, tungstates, borates, silicates, germanates and mixtures thereof.
18. The device of claim 1 wherein the second phosphor is selected from a group comprising (Gd 1-x-z Lu x ) 2 O 3 :Eu z , (Y 1-x-y-z Gd x Lu y ) 3 Al 5 O 12 :Eu z , Ba 2 (Y 1-x-y-z Gd x Lu y ) 2 Si 4 O 13 :Eu z , Ba 2 (Y 1-x-y-z Gd x Lu y ) 2 Ge 4 O 13 :Eu z , (Y 1-x-y-z Gd x Lu y )VO 4 :Eu z , (Y 1-x-y-z Gd x Lu y )OF:Eu z , (Y 1-x-y-z Gd x Lu y )OCl:Eu z , Ba(Y 1-x-y-z Gd x Lu y )B 9 O 16 :Eu z , Ba 3 (Y 1-x-y-z Gd x Lu y )(BO 3 ) 3 :Eu z , (Y 1-x-y-z Gd x Lu y ) 2 SiO 5 :Eu z , (Ca 1-a Sr a ) 3 (Y 1-w-x-y-z Lu w Ga w In y ) 2 Ge 3 O 12 :Eu z (a, w, x, y=0.0-1.0, z=0.0-0.2), (Ca 1-a Sr a ) 3 (Y 1-w-x-y-z Lu v Ga w In x ) 2 Ge 3 O 12 :Eu y Bi z (a, v, w, x=0.0-1.0, y, z=0.0-0.2), LaOM:Eu with M=(Br, Cl, I), Na 9 [(Y 1-x-y-z Lu x Gd y )W 10 O 36 ]:EU z , (Y 1-x-y-z Lu x Gd y )[P(Mo 3 O 10 ) 4 ]:Eu z (x, y=0.0-1.0, z=0.0-0.2), and mixtures thereof.
19. The device of claim 1 wherein composite light emitted from the device, the composite light comprising a portion of light emitted by the light emitting layer, a portion of light emitted by the first phosphor, and a portion of light emitted by the second phosphor, has a correlated color temperature between 2800 and 3300K.
20. The device of claim 1 wherein composite light emitted from the device, the composite light comprising a portion of light emitted by the light emitting layer, a portion of light emitted by the first phosphor, and a portion of light emitted by the second phosphor, has a color rendering index Ra between 80 and 87.