Integral lens light emitting diode

• US 3,981,023 A
• Filed: 09/16/1974
• Issued: 09/14/1976
• Est. Priority Date: 09/16/1974
• Status: Expired due to Term

• Current Assignee: Northern Electric PLC (Berkshire Hathaway Incorporated)
• Original Assignee: Northern Electric PLC (Berkshire Hathaway Incorporated)
• Inventors: King, Frederick David, Springthorpe, Anthony John
• Primary Examiner(s): Edlow, Martin H.
• Application Number:
  US05/506,095
• Time in Patent Office: 729 Days
• Field of Search: 357/16, 357/19, 357/17, 148/175
• US Class Current: 257/98
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: Y10S 148/05 Etch and refill
• CPC Class Codes: Y10S 148/051 Etching
• CPC Class Codes: Y10S 148/065 Gp III-V generic compounds-processing
• CPC Class Codes: Y10S 148/072 Heterojunctions
• CPC Class Codes: Y10S 148/145 Shaped junctions

Abstract

A light emitting diode structure has one or more convex lens formations formed on the surface through which the light issues to provide larger incident angles and reduce internal reflection. Conveniently the structure comprises a multi-layer epitaxially grown structure, and the lens or lenses may be formed integral with the outer surface.

Claims

1. An integral lens light emitting diode structure, said light emitting diode comprising a substrate of semiconductor material of one conductivity type and sequential layers of semiconductor material on one surface of said substrate, said layers comprising a first confining layer on said substrate, an active layer on said first confining layer and a second confining layer on said active layer, said first confining layer of the same conductivity type as said substrate, said second confining layer of the opposite conductivity type to said first confining layer, and said active layer of either conductivity type to produce a p-n junction between said active layer and one of said confining layers;

contact means on said substrate and said second confining layer to define a light emitting region in said active layer;

an aperture through said substrate to said first confining layer, in alignment with said light emitting region; and

a lens structure on said first confining layer, said lens structure extending into said aperture, integral with and forming part of said first confining layer.

2. A light emitting diode as claimed in claim 1, said lens formation comprising a plurality of convex lenses.

3. A light emitting diode as claimed in claim 2, including a single light emitting source common to all said lenses.

4. A light emitting diode as claimed in claim 2, including a plurality of light emitting sources, a source related to each lens.

5. An integral lens light emitting diode comprising:

a substrate of GaAs semiconductor material of one conductivity type;

a first confining layer of highly doped GaAs semiconductor material on said substrate, said first confining layer of the same conductivity type as said substrate;

an active layer of doped GaAs semiconductor material on said first confining layer, said active layer of either conductivity type;

a second confining layer of doped GaAs semiconductor material on said active layer, said second confining layer of the opposite conductivity type to that of said substrate;

contact means on said second confining layer and said substrate to produce a light emitting region in said active layer;

an aperture through said substrate in alignment with said light emitting region;

a lens structure on said first confining layer extending into said aperture, said lens structure integral with and forming part of said first confining layer.

6. A method of producing an integral lens light emitting diode, comprising:

masking a surface of a GaAs substrate of one conductivity type to define at least one lens position;

etching at least one concave depression in said substrate at said lens position;

sequentially growing on said substrate by liquid phase epitaxy a first confining layer of GaAs, an active layer of GaAs and a second confining layer of GaAs, said first confining layer extending into and filling said concave depression to form an integral lens structure, said first confining layer of the same conductivity type as said substrate, said second confining layer of opposite conductivity type as said substrate and said active layer of either conductivity type;

etching through said substrate to said first confining layer to form an aperture aligned with said lens structure;

forming contact means to produce a light emitting region aligned with said lens structure.