Light source using semiconductor devices mounted on a heat sink

• US 20030039122A1
• Filed: 08/24/2001
• Published: 02/27/2003
• Est. Priority Date: 08/24/2001
• Status: Active Grant

• Current Assignee: CAO Lighting, Inc. (CAO Group, Inc.)
• Original Assignee: CAO Group, Inc.
• Inventors: Cao, Densen
• Granted Patent: US 6,634,770 B2
• Time in Patent Office: Days
• US Class Current: 362/294
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 3/04 characterised by materials, surface treatments or coatings
• CPC Class Codes: F21Y 2107/40 on the sides of polyhedrons, e.g. cubes or pyramids
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F21Y 2115/30 Semiconductor lasers
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A semiconductor light source for illuminating a physical space has been invented. In various embodiments of the invention, a semiconductor such as and LED chip, laser chip, LED chip array, laser array, an array of chips, or a VCSEL chip is mounted on a heat sink. The heat sink may have multiple panels for mounting chips in various orientations. The chips may be mounted directly to a primary heat sink which is in turn mounted to a multi-panel secondary heat sink. A TE cooler and air circulation may be provided to enhance heat dissipation. An AC/DC converter may be included in the light source fitting.

Claims

1. A semiconductor light source for emitting light to illuminate a space used by humans, the semiconductor light source comprising:

an enclosure, said enclosure being fabricated from a material substantially transparent to white light,

a base to which said enclosure is mounted,

an interior volume within said enclosure,

a secondary heat sink located in said interior volume, said secondary heat sink being capable of drawing heat from one or more semiconductors devices,

a plurality of primary heat sinks mounted on said secondary heat sink, each of said primary heat sinks being smaller than said secondary heat sink,

a semiconductor chip capable of emitting light mounted on one of said primary heat sinks, said semiconductor chip being capable of emitting monochromatic light, said semiconductor chip being selected from the group consisting of light emitting diodes, light emitting diode arrays, laser chips, and VCSEL chips,

said chip including a substrate on which epitaxial layers are grown,

a buffer layer located on said substrate, said buffer layer serving to mitigate differences in material properties between said substrate and other epitaxial layers,

a first cladding layer serving to confine electron movement within the chip, said first cladding layer being adjacent said buffer layer,

an active layer, said active layer emitting light when electrons jump to a valance state,

a second cladding layer, said second cladding layer positioned so that said active layer lies between cladding layers, and

a contact layer on which an electron may be mounted for powering said chip, and

a coating for converting monochromatic light emitted by said chip to white light.

2. A device as recited in claim 1 further comprising a power module for powering the light source, said power module including a fitting for installation in a traditional light bulb socket and an AC/DC converter for converting AC power from traditional building wiring to DC power usable by a semiconductor devices.

3. A device as recited in claim 1 wherein at least one of said heat sink includes a material selected from the group consisting of include copper, aluminum, silicon carbide, boron nitride natural diamond, monocrystalline diamond, polycrystalline diamond, polycrystalline diamond compacts, diamond deposited through chemical vapor deposition and diamond deposited through physical vapor deposition.

4. A device as recited in claim 1 further comprising a quantity of heat conductive adhesive located between said chip and said primary heat sink and serving to conduct heat from said chip to said primary heat sink.

5. A device as recited in claim 1 further comprising a quantity of light reflective adhesive located between said chip and said primary heat sink.

6. A device as recited in claim 1 further comprising a first and a second reflective layers, each of said first and second reflective layers being located on opposite sides of said active layer, said reflective layers serving to reflect light emitted by said active layer.

7. A device as recited in claim 6 wherein said reflective layers include multiple quantum wells.

8. A device as recited in claim 1 wherein said substrate is selected from the group consisting of Si, GaAs, GaN, InP, sapphire, SiC, GaSb, InAs.

9. A device as recited in claim 1 wherein said substrate is electrically conductive.

10. A device as recited in claim 1 wherein said substrate is electrically insulative.

11. A device as recited in claim 1 wherein at least one of said epitaxial layers includes a material selected from the group consisting of GaN, AlGaN, AlN, AlGaN, GaInN, and GaInN.

12. A device as recited in claim 1 wherein said coating for converting monochromatic light is a phosphor coating located on said chip.

13. A semiconductor light source for creating white light to illuminate a space used by humans, the semiconductor light source comprising:

an enclosure, said enclosure being fabricated from a material substantially transparent to white light,

an interior volume within said enclosure,

a heat sink located in said interior volume, said heat sink being capable of drawing heat from one or more semiconductors devices,

a plurality of semiconductor devices located in said interior volume,

said semiconductor devices being capable of emitting light,

at least one of said semiconductor devices including

a substrate on which epitaxial layers are grown,

a buffer layer located on said substrate, said buffer layer serving to mitigate differences in material properties between said substrate and other epitaxial layers,

a first cladding layer serving to confine electron movement within the chip, said first cladding layer being adjacent said buffer layer,

an active layer, said active layer emitting light when electrons jump to a valance state,

a second cladding layer, said second cladding layer positioned so that said active layer lies between cladding layers, and

a contact layer on which an electron may be mounted for powering said chip.

14. A device as recited in claim 13 further comprising a coating for converting monochromatic light emitted by at least one of said semiconductor devices to white light.

15. A device as recited in claim 13 further comprising a first and a second reflective layers, each of said first and second reflective layers being located on opposite sides of said active layer, said reflective layers serving to reflect light emitted by said active layer.

16. A device as recited in claim 15 wherein said reflective layers include multiple quantum wells.

17. A device as recited in claim 13 wherein said heat sink includes a material selected from the group consisting of include copper, aluminum, silicon carbide, boron nitride natural diamond, monocrystalline diamond, polycrystalline diamond, polycrystalline diamond compacts, diamond deposited through chemical vapor deposition and diamond deposited through physical vapor deposition.

18. A semiconductor light source for creating white light to illuminate a space used by humans, the semiconductor light source comprising:

an enclosure, said enclosure being fabricated from a material substantially transparent to white light,

a base to which said enclosure is mounted,

an interior volume within said enclosure,

a heat sink located in said interior volume, said heat sink being capable of drawing heat from one or more semiconductors devices mounted on it,

a plurality of vertical cavity surface emitting laser chips capable of emitting light mounted on said heat sink,

said vertical cavity surface emitting laser chips including

a substrate,

a plurality of epitaxial layers of semiconductor materials,

panel of a conductive material located on said semiconductor materials, and

a plurality of apertures in said panel, said apertures being formed to permit light to pass therethrough, and

a coating for converting monochromatic light emitted by said chip to white light.

19. A device as recited in claim 18 wherein said panel of conductive material includes a material selected from the group consisting of Au/Ge and Au/Zn.

20. A devices as recited in claim 18 further comprising a primary heat sink mounted on said heat sink, said primary heat sink having one of said vertical cavity surface emitting laser chips mounted on it.