Semiconductor light emitting device
View Patent ↗According to one embodiment, a semiconductor light emitting device includes a light emitting element, a phosphor layer, and a fluorescent reflection film. The phosphor layer has a transparent medium, a phosphor dispersed in the transparent medium, and a particle dispersed in the transparent medium. The phosphor is excited by the excitation light so as to emit a fluorescence. The particle is a magnitude of not more than 1/10 a wavelength of the excitation light. The particle has a different refractive index from a refractive index of the transparent medium. The fluorescent reflection film is provided between the light emitting element and the phosphor layer. The fluorescent reflection film has a higher reflectance with respect to a fluorescent wavelength of the phosphor, than a reflectance with respect to the wavelength of the excitation lights.
1. A semiconductor light emitting device comprising:
a light emitting element including a semiconductor layer, the semiconductor layer having a first face, a side surface continued from the first face, and an active layer configured to emit a light, a p-side electrode provided on the semiconductor layer, and an n-side electrode provided on the semiconductor layer;
a p-side interconnection portion being electrically connected to the p-side electrode;
an n-side interconnection portion being electrically connected to the n-side electrode;
an insulating material disposed on the side surface of the semiconductor layer, a periphery of the p-side interconnection portion, and a periphery of the n-side interconnection portion, the insulating material blocking light emitted by the light emitting element;
a phosphor layer disposed on the insulating material and the first face of the semiconductor layer, the phosphor layer comprising a transparent medium, phosphor dispersed in the transparent medium, and particles dispersed in the transparent medium, the phosphor, when excited by the light, emitting a fluorescence, the particles being of a magnitude of not more than 1/10 of a wavelength of the light and having a refractive index that is different from a refractive index of the transparent medium; and
a fluorescent reflection film provided between the light emitting element and the phosphor layer, the fluorescent reflection film having a reflectance with respect to a wavelength of the fluorescence emitted by the phosphor that is greater than a reflectance with respect to the wavelength of the light, the fluorescent reflection film being in contact with a substantial portion of the first face of the semiconductor layer and a surface of the insulating material disposed on the side surface of the semiconductor layer.
2. The device according to claim 1 , wherein an average grain diameter of the particles is not less than 15 nm and not more than 45 nm.
3. The device according to claim 1 , wherein
the semiconductor layer includes a second face opposite to the first face,
the p-side electrode is provided on the second face in a region including the active layer, and
the n-side electrode is provided on the second face in a region not including the active layer.
4. The device according to claim 3 ,
wherein the insulating material includes a first insulating material provided on a side of the second face, and having a first opening communicating with the p-side electrode and a second opening communicating with the n-side electrode,
the p-side interconnection portion is provided on the first insulating material, and electrically connected to the p-side electrode through the first opening, and
the n-side interconnection portion is provided on the first insulating material, and electrically connected to the n-side electrode through the second opening.
5. The device according to claim 4 , wherein the first insulating material is disposed on the side surface continued from the first face of the semiconductor layer.
6. The device according to claim 4 , wherein the insulating material includes a second insulating material provided between the p-side interconnection portion and the n-side interconnection portion.
7. The device according to claim 6 , wherein the second insulating material is disposed on the periphery of the p-side interconnection portion and the periphery of the n-side interconnection portion.
8. The device according to claim 4 , wherein the p-side interconnection portion includes:
a p-side interconnection layer provided inside the first opening and on the first insulating material; and
a p-side metal pillar provided on the p-side interconnection layer and being thicker than the p-side interconnection layer, and
the n-side interconnection portion includes:
an n-side interconnection layer provided inside the second opening and on the first insulating material; and
an n-side metal pillar provided on the n-side interconnection layer and being thicker than the n-side interconnection layer.
9. The device according to claim 1 , wherein the transparent medium is a resin layer.
10. The device according to claim 1 , wherein the fluorescent reflection film is a silicon nitride film.
11. The device according to claim 1 , further comprising a top coat film provided on the phosphor layer.
12. The device according to claim 11 , wherein the top coat film is a silicon nitride film.
13. The device according to claim 11 , wherein the top coat film is a silicon oxide film.
14. The device according to claim 11 , wherein the top coat film is a LiF film.
15. The device according to claim 11 , wherein the top coat film has a refractive index between a refractive index of the transparent medium of the phosphor layer and a refractive index of an air.
16. The device according to claim 11 , wherein
the transparent medium of the phosphor layer is a resin layer, and
the top coat film has a lower adhesion than a adhesion of the resin layer.
17. The device according to claim 11 , wherein a grain diameter of the particles is λ/10 n in the case in which the wavelength of the light of the light emitting element is set to λ and a refractive index of the transparent medium of the phosphor layer is set to n.
18. A semiconductor light emitting device, comprising:
a light emitting element including a semiconductor layer, the semiconductor layer having a first face, a side surface continued from the first face, and an active layer configured to emit a first light;
an insulating material covering the side surface of the semiconductor layer;
a phosphor layer disposed on the light emitting element, the phosphor layer comprising a transparent medium, phosphor dispersed in the transparent medium, and particles dispersed in the transparent medium, the phosphor, when excited by the first light, emitting a fluorescence, the particles being of a magnitude of not more than 1/10 of a wavelength of the first light and having a refractive index that is different from a refractive index of the transparent medium; and
a fluorescent reflection film provided as a continuous layer between the light emitting element and the phosphor layer, the fluorescent reflection film having a reflectance with respect to a wavelength of the fluorescence emitted by the phosphor that is greater than a reflectance with respect to the wavelength of the first light.
19. The device according to claim 18 , wherein the fluorescent reflection film is a planar film directly contacting the first face of the semiconductor layer.
20. The device according to claim 18 , wherein the fluorescent reflection film is directly contacting a surface of the insulating material covering the side surface of the semiconductor layer.