LED white light source with broadband excitation

• US 6,734,467 B2
• Filed: 05/03/2002
• Issued: 05/11/2004
• Est. Priority Date: 11/03/1999
• Status: Expired due to Term

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Härle, Volker, Stath, Norbert, Schlereth, Karl-Heinz
• Primary Examiner(s): CRANE, SARA W
• Application Number:
  US10/137,885
• Publication Number:
  US 20020167014A1
• Time in Patent Office: 739 Days
• Field of Search: 257/79, 257/89, 257/90, 257/96, 257/100
• US Class Current: 257/89
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/50 Wavelength conversion elements

Abstract

A white light source is described and has a UV-/blue-emitting semiconductor LED and an embedding compound provided with phosphor particles. The LED is provided with a plurality of light-emitting zones that are applied within a layer structure on a common substrate. An emission maxima of the light-emitting zones are energetically detuned relative to one another by different choice of the composition or of the layer thickness of the semiconductor material.

Claims

1. A white light source, comprising:

a semiconductor light emitting diode (LED) having a light exit side and a main radiating direction, said semiconductor LED emitting a light; and

an encapsulation at least partly surrounding said semiconductor LED and made of a transparent material containing a converter substance for at least partial wavelength conversion of the light emitted by said semiconductor LED;

said semiconductor LED having at least two light-emitting zones embodied such that a maxima of their emission spectra are energetically detuned relative to one another and enerqetically lie above an emission spectrum of said converter substance, said light-emitting zones disposed one behind another in said main radiating direction of said semiconductor LED such that an energy of an emission maximum increases in a direction of said light exit side of said semiconductor LED.

2. The white light source according to claim 1, wherein said semiconductor LED has exactly one pn junction and said light-emitting zones are embodied by a corresponding number of quantum well layers having at least one of different thicknesses and different material compositions.

3. The white light source according to claim 1, wherein said light-emitting zones are formed by a corresponding number of pn junctions.

4. The white light source according to claim 3, wherein said pn junctions are formed from a bulk material having different material compositions.

5. The white light source according to claim 3, wherein at least one of said pn junctions contains a quantum well selected from the group consisting of a single quantum well layer and a multiple quantum well layer.

6. The white light source according to claim 5, wherein each of said pn junctions contains said quantum well selected from the group consisting of a single quantum well layer and a multiple quantum well layer, said quantum well of different ones of said pn junctions have at least one of different thicknesses and different material compositions.

7. The white light Source according to claim 3, wherein:

each of said pn junctions has an n-type region and a p-type region; and

said semiconductor LED has a n+p + tunnel junction contact-connecting respectively adjacent ones of said pn junctions to one another, said n⁺p⁺ tunnel junction containing an n³⁰ -doped layer and a directly adjoining p⁺-doped layer, said n⁺-doped layer adjoining said n-type region of one of said pn junctions and said p⁺-doped layer adjoining said p-type region of another one of said pn junctions, and said n⁺-doped layer and said p⁺-doped layer having an n⁺-type and p⁺-type doping concentration, respectively, being chosen in such a way as to produce a relatively low electrical resistance of said n+p+ tunnel junction during operation.

8. The white light source according to claim 3, wherein said semiconductor LED has a metallic contact layer respectively electrically connecting adjacent ones of said pn junctions to one another.

9. The white light source according to claim 8, wherein said metallic contact layer is a solder layer.

10. The white light source according to claim 1, wherein said semiconductor LED is constructed on a basis of one of GaN and InGaN.

11. The white light source according to claim 2, wherein said quantum well layers are selected from the group consisting of a single quantum well layer and multiple quantum well layers.

12. The white light source according to claim 1, wherein said emitted light has a substantially uniform intensity profile.

13. The white light source according to claim 1, wherein said emitted light has an emission spectrum with a substantially uniform intensity distribution to close spectral holes.