LIGHT EMITTING DIODES OF THE INJECTION TYPE

• US 3,813,587 A
• Filed: 05/04/1973
• Issued: 05/28/1974
• Est. Priority Date: 05/04/1972
• Status: Expired due to Term

• Current Assignee: Hazime Kusumoto, Jun-Ichi Umeda, Junio Aiki, Kazuhiro Kurata
• Original Assignee: Hazime Kusumoto, Jun-Ichi Umeda, Junio Aiki, Kazuhiro Kurata
• Inventors: Umeda, Jun-Ichi, Kurata, Kazuhiro, Aiki, Junio, Kusumoto, Hazime
• Primary Examiner(s): Edlow, Martin H.
• Application Number:
  US05/357,088
• Time in Patent Office: 389 Days
• Field of Search: 317/235N,235AC,235AK,235AJ
• US Class Current: 257/79
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 33/00 Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof H10K50/00 takes precedence; devices consisting of a plurality of semiconductor components formed in or on a common substrate and including semiconductor components having potential barriers, specially adapted for light emission H01L27/15; semiconductor lasers H01S5/00
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate

Abstract

In a PN junction light emitting diode of the injection type comprising a first semiconductor region having a forbidden band width equal at most, to the width of a PN junction forbidden band, a second semiconductor region having a forbidden band width greater than the width of a PN junction forbidden band, and at least one pair of electrodes affixed to each of a P conductive region and an N conductive region, the light extraction efficiency can be greatly increased by constructing the diode so that the sum of the area SA of the boundary between the first semiconductor region and the second semiconductor region and the bottom area SC of the electrode mounted on the surface of the second semiconductor region (SA + SC) is sufficiently smaller than the area S obtained by subtracting the area (SA + SC) from the total surface area of the second semiconductor region.

Claims

1. A light emitting diode of the injection type comprising:

a semiconductor body including a first semiconductor layer including a first semiconductor region of a first conductivity type and a second semiconductor layer having a second semiconductor region of a second conductivity type, opposite said first conductivity type, forming a PN junction with said first region at the interface between said first and second layers, said first semiconductor region having a forbidden band width equal at most to the forbidden band width of said PN junction and said second semiconductor region having a forbidden band width greater than the forbidden band width of said PN junction; and

first and second electrodes respectively connected to the surfaces of said first and second semiconductor layers;

wherein the sum (SA + SC) of the areas SA of the boundary surface between said first region of said first semiconductor layer and said second region of said second semiconductor layer and the area SC of the surface of said second electrode contacting said second semiconductor layer is less than the difference between the total surface area of said second semiconductor layer and said sum (SA + SC) by a prescribed amount.

2. A light emitting diode according to claim 1, wherein said prescribed amount is 1/10.

3. A light emitting diode according to claim 2, wherein each of said first and second semiconductor layers is composed of a compound selected from the group consisting of GaAs1 xPx, Ga1 xAlx P and Ga1 xInxP, wherein x has a value within a range from 0 to 1, and varies within said range in said layers.

4. A light emitting diode according to claim 1, wherein each of said first and second semiconductor layers is composed of a compound selected from the group consisting of GaAs1 xPx, Ga1 xAlxP and Ga1 xInxP, wherein 0 <

or = x <

or = 1 and said first and second regions forming said PN junction at the interface therebetween are formed of a compound selected from the group consisting of GaAs1 xPx 0 <

or = x <

or = 0.45, Ga1 xAlxAs 0 <

or = x <

or = 0.31 and In1 xGaxP 0 <

or = x <

0.8.

5. A light emitting diode according to claim 1, wherein each of said first and second semiconductor layers is composed of GaAs1 xPx 0 <

x <

1, the forbidden band width in said layers depending upon the value of x.

6. A light emitting diode according to claim 5, wherein said second layer includes a GaP crystal region extending from said second region in a direction orthogonal to said PN junction to a thickness greater than 50 Mu .

7. A light emitting diode according to claim 6, wherein said first and second regions forming said PN junction at the interface therebetween are composed of GaAs1 xPx 0 <

or = x <

or = 0.45.

8. A light emitting diode of the injection type comprising:

a GaP substrate of N-type conductivity;

an epitaxial crystal layer of GaAs1 xPx, 0 <

x <

1 having N-type conductivity disposed on said substrate with the value of x decreasing with an increase in the distance within said layer from the surface of said substrate on which said layer is disposed and having a mesa-shaped portion opposite the surface of said substrate;

a P-type diffusion region extending into the mesa-shaped portion of said epitaxial crystal layer from the surface thereof opposite the surface disposed on said substrate to that position within said epitaxial crystal layer where the value of x is said epitaxial crystal layer of GaAs1 xPx is within the range of 0 to 0.45, said P-type diffusion region forming a PN junction with said N-type crystal layer; and

an electrode disposed on said GaP substrate;

wherein the sum of the area of said PN junction and the contact surface of said electrode on said GaP substrate is less than one-tenth of the surface area of the substrate and the N-type crystal less the area of the contact surface of said electrode.

9. An injection type light emitting diode comprising:

a semiconductor substrate of a first conductivity type having a first surface on one side thereof and a second surface on the opposite side thereof;

a first semiconductor region of said first conductivity type disposed on said second surface of said semiconductor substrate;

at least one second semiconductor region of a second conductivity type opposite side first conductivity type contacting said first semiconductor region at at least one surface portion thereof and thereby defining at least one PN junction therebetween; and

a first electrode contacting said first surface of said semiconductor substrate;

wherein the sum (SA + SC) of the total area SA of the interface between said first and said at least one second semiconductor region defining said at least one PN junction therebetween and the area SC of the contact surface of said first electrode with said first surface of said semiconductor substrate is less than the difference between the total outer surface area of said second semiconductor region and said substrate and said sum (SA + SC) by a prescribed amount.

10. An injection type light emitting diode according to claim 9, wherein said prescribed amount is one-tenth.

11. An injection type light emitting diode according to claim 10, wherein said at least one second semiconductor region comprises a plurality of second semiconductor regions.

12. An injection type light emitting diode according to claim 10, wherein said first semiconductor region has at least one mesa-shaped portion on which said at least one second semiconductor region is disposed.

13. An injection type light emitting diode according to claim 10, further including at least one second electrode disposed in contact with said at least one second semiconductor region.

14. An injection type light emitting diode according to claim 10, wherein said semiconductor substrate is an N-type GaP substrate and each of said first and second semiconductor regions is an N-type semiconductor crystal of a material selected from the group consisting of GaAs1 xPx, Ga1 xAlxP and GaxInxP, where 0 <

or = x <

or = 1.

15. An injection type light emitting diode according to claim 14, wherein said material is GaAs1 xPx, wherein 0.4 <

or = x <

or = 1.

16. An injection type light emitting diode according to claim 15, wherein said at least one second semiconductor region comprises a plurality of second semiconductor regions, each respectively formed on a corresponding plurality of mesa-shaped portions of said first semiconductor region.