Light emitting diode and method of making the same

• US 4,339,689 A
• Filed: 01/21/1980
• Issued: 07/13/1982
• Est. Priority Date: 01/29/1979
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kazumura, Masaru, Yamanaka, Haruyoshi
• Primary Examiner(s): LAROCHE, EUGENE
• Application Number:
  US06/115,249
• Time in Patent Office: 904 Days
• Field of Search: 313/498, 313/499, 357/17, 29/569 C, 148/175, 313/110
• US Class Current: 313/499
• CPC Class Codes: G02B 6/4206 Optical features G02B6/4207, G02B6/421 take precedence
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: Y10S 438/928 Front and rear surface processing

Abstract

A light-emitting diode is comprised of:

a semiconductor active layer,

a semiconductor first clad layer formed on a surface of said semiconductor active layer, and

a protrusion formed unitarily on a surface of said first clad layer for facing an input end of a light guide for light coupling therewith.

A method of manufacturing the light emitting diode is comprised of the steps of

forming a recess on one face of a semiconductor substrate,

forming a semiconductor first clad layer on the abovementioned face of the semiconductor substrate, and

selectively etching the substrate from the other face thereof so as to form a through-hole reaching said recess on said one face of the semiconductor substrate, thereby exposing at least a protrusion of said semiconductor first clad layer formed in said recess.

Claims

1. A light emitting diode having an improved surface for coupling with a light guide, comprising:

a semiconductor active layer,

a semiconductor first clad layer formed on a surface of said semiconductor active layer;

a protrustion formed unitarily on a surface of said first clad layer for facing an input end of said light guide to effect light coupling therewith, and wherein

a depth X measured from the surface of said clad layer to a light emitting region of said clad layer and a radius R of said protrusion have a relationship of 0<

X/R≦

0.6.

2. A light emitting diode in accordance with claim 1, wherein said light guide is an optical fiber.

3. A light emitting diode in accordance with claim 1, or 2 wherein said protrusion forms a light converging lens.

4. A light emitting diode in accordance with claim 1, or 2 wherein said protrusion is of a hemispherical shape.

5. A light emitting diode in accordance with claim 1, or 2 wherein said semiconductor first clad layer is a Ga_1-x Al_x As layer (0<

x≦

1) of n-type conductivity and said active layer is a Ga_1-y Al_y As layer (0≦

y<

x) of p-type conductivity.

6. A light emitting diode in accordance with claim 5, which further comprises a third layer of Ga_1-x'"'"' Al_x'"'"' As (y<

x'"'"'≦

1) of p-type conductivity on the rear surface of said active layer and a fourth layer of GaAs of p-type conductivity on the rear surface of said third layer.

7. A light emitting diode in accordance with claim 1, or 2 wherein a substrate having a through-hole is provided on the surface of said first clad layer in such a manner that said protrusion is exposed in said through-hole.

8. A light emitting diode in accordance with claim 1 or 2, wherein the radius of said protrusion is smaller than that of the end face of the light guide.

9. A light emitting diode in accordance with claim 1 or 2, wherein the radius of said protrusion is smaller than that of the core of the light guide.

10. A light emitting diode formed by the method comprising the steps of:

forming a recess of a semi-spherical shape on one face of a semiconductor substrate,

forming a semiconductor first clad layer on the above-mentioned face of the semiconductor substrate,

forming a semiconductor active layer on said semiconductor first clad layer, and

selectively etching the substrate from the other face thereof so as to form a through-hole reaching said recess on said one face of the semiconductor substrate, thereby to expose at least a protrusion of said semiconductor first clad layer formed in said recess,

wherein the forming of said recess is made in such a manner that a depth X measured from the center of a hemisphere of said protrusion to a light emitting region and a radius R of the hemisphere of said protrustion have a relationship of 0<

X/R≦

0.6.

11. A light emitting diode formed in accordance with claim 10, wherein said first clad layer is an epitaxial growth layer of Ga_1-x Al_x As (0<

x≦

1) of n-type conductivity, on which a semiconductor active layer of Ga_1-y Al_y As (0≦

y<

x) is subsequently formed by sequential epitaxial growth method.

12. A light emitting diode formed in accordance with claim 11, wherein a Ga_1-x'"'"' Al_x'"'"' As layer (y<

x'"'"'≦

1) of p-type conductivity and a GaAs layer of p-type conductivity are subsequently formed by sequential epitaxial growth method on said active layer.

13. A light emitting diode having an improved surface for coupling with a light guide, comprising:

a semiconductor active layer,

a semiconductor first clad layer formed on a surface of said semiconductor active layer,

a hemispherical protrusion formed unitarily on a surface of said first clad layer for facing an input end of said light guide to effect light coupling therewith, wherein a depth X measured from the center of the hemisphere of said protrusion to a light emitting region and a radius R of the hemisphere of said protrustion have a relationship of 0<

X/R≦

0.6.

14. A light emitting diode in accordance with claim 13, wherein a substrate having a conic through-hole is provided on the surface of said first clad layer in such a manner that said protrusion is exposed in said conic through-hole.