SILICON CARBIDE LAMP MOUNTED ON A CERAMIC OF POOR THERMAL CONDUCTIVITY

• US 3,715,636 A
• Filed: 01/03/1972
• Issued: 02/06/1973
• Est. Priority Date: 01/03/1972
• Status: Expired due to Term

• Current Assignee: Mary S. Jaffe, Ralph M. Potter
• Original Assignee: Mary S. Jaffe, Ralph M. Potter
• Inventors: Jaffe, Mary S., Potter, Ralph M.
• Primary Examiner(s): Edlow, Martin H.
• Application Number:
  US05/215,069
• Time in Patent Office: 400 Days
• Field of Search: 317/235N,234G,234N,234D,237
• US Class Current: 257/76
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• 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 33/343 characterised by the doping materials
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements

Abstract

A boron-doped silicon carbide light-emitting diode chip is mounted, such as on a support member of porous ceramic or other material of similarly low thermal conductivity, so as to operate at a temperature of at least 150*C. Such a construction increases the amount of light produced by the boron-doped silicon carbide diode, due to increased operating temperature. A cover is placed over the diode to prevent convection cooling, thus further increasing the operating temperature and hence the light output. Instead of boron doping, the silicon carbide diode can be doped with other materials that produce similarly deep acceptor levels.

Claims

1. A silicon carbide lamp construction comprising a silicon carbide light-emitting diode having a PN junction formed with one or more dopants including boron or other element which produces a similarly deep acceptor level, said PN junction being between and substantially parallel to two surfaces of the diode, a support member of porous ceramic or other material of similarly low thermal conductivity, means mounting said diode on said support member, and means making a pair of electrical connections to said diode at opposite sides of the PN junction so that current can be made to flow through said PN junction.

2. A lamp construction as claimed in claim 1, including means providing an enclosed space surrounding said diode to reduce convection cooling of the diode.

3. A lamp construction as claimed in claim 2, in which said enclosed space comprises a vacuum.

4. A lamp construction as claimed in claim 2, in which said enclosed space is filled with argon or other inert gas providing a degree of thermal insulation at least as great as argon.

5. A lamp construction as claimed in claim 1, including current supply means connected to said electrical connections and supplying an amount of operating current through said diode so as to cause the diode to heat to an operating temperature of at least 150*C.

6. A lamp construction as claimed in claim 1, in which one of said electrical connections to the diode comprises a metal layer provided on a surface of said support member, means attaching said diode at one of said surfaces thereof to said metal layer, said metal layer being of larger area than that of said diode whereby a portion of said metal layer extends laterally from said one surface of the diode, and means making electrical connection to said laterally extending portion of the metal layer.

7. A lamp construction as claimed in claim 6, including a metal header provided with a first connector lead attached thereto and extending therefrom and a second connector lead positioned substantially parallel to said first connector lead and extending through an opening in said header to the upper surface thereof and electrically insulated therefrom, said support member having a bottom surface and a top surface, means attaching said support member at the bottom surface thereof to said upper surface of the header, said metal layer being provided on said top surface of the support member, means electrically connecting one of said connector leads to said laterally extending portion of the metal layer thereby making electrical connection to the bottom surface of said diode, and means electrically connecting the other one of said connectoR leads to the top surface of said diode.

8. A lamp construction as claimed in claim 7, including a light-transparent cup-like cover member positioned over and around said diode and attached at the rim thereof to said header.

9. A lamp construction as claimed in claim 8, in which said header and cover member define an enclosed space, said enclosed space being evacuated.

10. A lamp construction as claimed in claim 8, in which said header and cover member define an enclosed space, said enclosed space being filled with argon or other inert gas providing a degree of thermal insulation at least as great as argon.

11. A lamp construction as claimed in claim 6, in which said support member has substantially mutually parallel top and bottom surfaces and constitutes a header, said metal layer being provided on said top surface of the header, first and second mutually parallel connector leads positioned through vertical openings through said header and extending downwardly therefrom, the top portion of the first of said connector leads being in electrical contact with said metal layer thereby making electrical connection to the bottom surface of said diode, and means electrically connecting the top portion of said second connector lead to the top surface of said diode.

12. A lamp construction as claimed in claim 11, including a light-transparent cup-like cover member positioned over and around said diode and attached at the rim thereof to said header.

13. A lamp construction as claimed in claim 12, in which said header and cover member define an enclosed space, said enclosed space being evacuated.

14. A lamp construction as claimed in claim 12, in which said header and cover member define an enclosed space, said enclosed space being filled with argon or other inert gas providing a degree of thermal insulation at least as great as argon.

15. A silicon carbide lamp construction comprising a silicon carbide light-emitting diode having a PN junction formed with one or more dopants including boron or other element which produces a similarly deep acceptor level, said diode being designed for operation with a given value of operating current flow through said PN junction, said diode having the characteristic of producing heat in response to said operating current flow, and mounting means for supporting and making electrical connections to said diode, said mounting means providing sufficient thermal insulation for said diode so as to cause said heat produced by the operating current flow to raise the operating temperature of said diode to at least 150*C.