Infrared LED

Abstract

An infrared LED having a monolithic and stacked structure, having an n-doped base substrate, which includes GaAs, a lower cladding layer, an active layer for generating infrared radiation, an upper cladding layer, a current distribution layer and an upper contact layer. The layers being preferably disposed in the specified order. A first tunnel diode is disposed between the upper cladding layer and the current distribution layer, and the current distribution layer predominantly including an n-doped, Ga-containing layer having a Ga content>1%.

Claims

1. An infrared LED having a monolithic and stacked structure, the infrared LED comprising: a n-doped base substrate that includes GaAs; a lower cladding layer; an active layer for generating infrared radiation; an upper cladding layer; a current distribution layer; an upper contact layer that is epitaxially grown; and a first tunnel diode disposed between the upper cladding layer and the current distribution layer, wherein the current distribution layer includes a n-doped Ga-containing layer having a Ga content>1%, the current distribution layer having a layer resistance R.sub.<75, the current distribution layer being made from GaAs or AlGaAs or InGaP, and wherein the first tunnel diode has a thickness between 30 nm and 150 nm and includes an As-containing p layer doped with carbon having a dopant concentration>110.sup.19 N/cm.sup.3, and the first tunnel diode includes a P-containing n layer doped with tellurium having a dopant concentration>310.sup.18 N/cm.sup.3.

2. The infrared LED according to claim 1, wherein a second tunnel diode is arranged between the current distribution layer and the upper contact layer, and wherein the upper contact layer is p-doped.

3. The infrared LED according to claim 1, wherein the lower cladding layer includes a compound made from GaAs or from AlGaAs or from InGaAsP or from GaAsP or from InGaP or from AlInGaP.

4. The infrared LED according to claim 1, wherein the upper cladding layer includes a compound made from GaAs or from AlGaAs or from InGaAsP or from GaAsP or from InGaP or from AlInGaP.

5. The infrared LED according to claim 1, wherein the active layer is made from a multiple quantum well structure and has a thickness between 15 nm and 350 nm or between 30 nm and 300 nm.

6. The infrared LED according to claim 1, wherein the current distribution layer has a thickness between 0.1 m and 3.0 m.

7. The infrared LED according to claim 1, wherein the current distribution layer includes a n-doped Al.sub.xGa.sub.1-xAs layer having an Al content x between 0% and 20%.

8. The infrared LED according to claim 1, wherein the current distribution layer has a n-dopant concentration>1.0E18 N/cm.sup.3.

9. The infrared LED according to claim 1, wherein the active layer is made from an In.sub.xGa.sub.1-xAs/GaAs.sub.1-yP.sub.y multiple quantum well structure, where 0.1x0.2 and 0.1y0.3.

10. The infrared LED according to claim 1, wherein the lower cladding layer has a n doping, or wherein the upper cladding layer has a p doping.

11. The infrared LED according to claim 1, wherein the tunnel diode is transparent to the radiation generated in the active layer.

12. The infrared LED according to claim 1, wherein the current distribution layer has an absorption coefficient of less than 150/cm for the radiation generated in the active layer.

13. The infrared LED according to claim 2, wherein the first tunnel diode or the second tunnel diode includes an As-containing layer, the As-containing layer being doped with carbon, or includes a P-containing layer, the P-containing layer being doped with tellurium.

14. The infrared LED according to claim 2, wherein the first tunnel diode or the second tunnel diode includes a n-doped layer having a dopant concentration>310.sup.18 N/cm.sup.3 and a p-doped layer having a dopant concentration>110.sup.19 N/cm.sup.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 shows a schematic view of an embodiment of an infrared LED according to the invention;

(3) FIG. 2 shows a schematic view of an embodiment of an infrared LED according to the invention; and

(4) FIG. 3 shows a schematic view of an infrared LED according to the conventional art.

DETAILED DESCRIPTION

(5) The representation in FIG. 1 shows a view of an embodiment, comprising an infrared LED having a monolithic, stacked, epitaxially grown structure 10, which includes, in the following order, an n-doped base substrate 14 made from GaAs, an n-doped cladding layer 16, an MQW layer 18, a p-doped cladding layer 20, a first tunnel diode 22, an n-doped current distribution layer 24 and a second n-doped contact layer 26. In processing the epitaxially grown structure into LED chips, a first contact 12 as well as a second n-contact 30 are applied during the further course of the process.

(6) An embodiment of an infrared LED is illustrated in the representation in FIG. 2, which has an epitaxially grown structure 10. Only the differences from the illustration in FIG. 1 are explained below. Current distribution layer 24 is followed by a second tunnel diode 28, and subsequent upper contact layer 26 is provided with a p-doped design. Subsequent contact 30 is therefore also designed as a metal contact to a p-semiconductor layer. The contacts of infrared LED structure 10 according to the invention can correspond hereby to the contacts of an infrared LED structure 10 known according to the prior art without tunnel diode 22 and n-doped current distribution layer 24, as illustrated in FIG. 3. It is understood that current distribution layer 24 according to the prior art in FIG. 3 is p-doped.

(7) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.