Light emitting diode

• US 20030230757A1
• Filed: 03/24/2003
• Published: 12/18/2003
• Est. Priority Date: 04/04/2002
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Suehiro, Yoshinobu, Takahashi, Yuji, Hirano, Atsuo, Takashima, Tatsuya, Kawano, Hitomi
• Granted Patent: US 6,943,379 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material

Abstract

In a light emitting diode, a blue light emitting element is mounted on a base having a cup through a phosphor-containing mount so that the light emitting element is located within the cup and is mounted on the bottom of the cup through the phosphor-containing mount. The light emitting diode includes a light emitting element and a p electrode. By virtue of the above construction, blue light emitted from the light emitting element can be reflected from the lower surface of the p electrode without being radiated directly from the upper surface of the light emitting element to the outside of the light emitting diode. As a result, the blue light emitted from the light emitting element can be efficiently mixed with yellow light given off from the phosphor in the phosphor-containing mount to provide white light which is radiated to the outside of the light emitting diode with high efficiency. The white light can be perceived by a viewer to be uniformly radiated from the light radiating surface of the light emitting diode.

Claims

1. A light emitting diode comprising:

a base;

a light emitting element formed of a compound semiconductor provided on the base;

a mount which is provided between the base and the light emitting element to bond the base to the light emitting element, said mount containing therein a phosphor which absorbs light emitted from the light emitting element and gives off light with a wavelength different from the absorbed light; and

a light nontransparent conductive layer which is provided in its emitted light viewing surface side and reflects the light emitted from a light emitting layer of the light emitting element toward the mount.

2. The light emitting diode according to claim 1, wherein the base is a metallic mount lead provided with a reflector for reflecting the light emitted from the light emitting element toward the emitted light viewing surface side.

3. The light emitting diode according to claim 1, wherein the conductive layer is a p electrode formed of at least one metal or an alloy of two or more metals selected from the group consisting of rhodium (Rh), gold (Au), platinum (Pt), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), cobalt (Co), magnesium (Mg), palladium (Pd), vanadium (V), manganese (Mn), bismuth (Bi), tin (Sn), and rhenium (Re).

4. The light emitting diode according to claim 3, wherein the p electrode is provided on the whole surface of a p-type layer in the light emitting element.

5. The light emitting diode according to claim 3, wherein the p electrode has been wire bonded directly to the base.

6. The light emitting diode according to claim 1, wherein the light emitting element is formed of a gallium nitride compound semiconductor which emits blue light.

7. The light emitting diode according to claim 6, wherein the phosphor is cerium-doped yttrium-aluminum-garnet which absorbs blue light and gives off yellow light.

8. The light emitting diode according to claim 1, wherein the light emitting element, the mount, and the conductive layer have been sealed with a light transparent resin which has been molded in a lens form as a whole.

9. The light emitting diode according to claim 1, wherein the base is an insulating board with a lead pattern being formed on the upper and lower sides thereof and a reflector for reflecting the light emitted from the light emitting element toward the emitted light viewing surface side is provided on the insulating board so as to surround the light emitting element.

10. The light emitting diode according to claim 9, wherein a light transparent resin for sealing the light emitting element, the mount, and the conductive layer is provided in a space within the reflector.

11. A light emitting diode comprising:

a base;

a light emitting element formed of a compound semiconductor provided on the base;

a mount which is provided between the base and the light emitting element to bond the base to the light emitting element, said mount containing therein a phosphor which absorbs light emitted from the light emitting element and gives off light with a wavelength different from the absorbed light; and

a phosphor-mixed layer that is provided on the light emitting surface side and side surface of the light emitting element and contains a phosphor which absorbs light emitted from the light emitting element and gives off light with a wavelength different from the absorbed light.

12. The light emitting diode according to claim 11, wherein the concentration of the phosphor in the phosphor-mixed layer is lower than the concentration of the phosphor in the mount.

13. The light emitting diode according to claim 11, wherein a reflector is provided on the light emitting surface side so as to face the light emitting element to reflect the light emitted from the light emitting element before the radiation of the light to the outside of the light emitting diode.

14. The light emitting diode according to claim 11, wherein the base is a pair of leads for supplying electric power to the light emitting element.

15. The light emitting diode according to claim 11, wherein the light emitting element, the mount, and the phosphor-mixed layer have been sealed with a light transparent resin which has been molded in a lens form as a whole.

16. The light emitting diode according to claim 13, wherein a light shielding sheet having one or more openings is provided on the emitted light viewing surface side as viewed from the base side.

17. The light emitting diode according to claim 11, wherein the light emitting element, the mount, and the phosphor-mixed layer have been sealed with a light transparent resin which has been molded to form a reflecting surface in such a shape that a part of a parabola, of which the focal point is the light emitting surface of the light emitting element with the axis of symmetry being the horizontal direction, has been rotated in a vertical direction.

18. The light emitting diode according to claim 11, wherein the light emitting element is formed of a gallium nitride compound semiconductor which emits blue light.

19. The light emitting diode according to claim 11, wherein the phosphor is cerium-doped yttrium-aluminum-garnet which absorbs blue light and emits yellow light.