GB2293488A - Alingap light emitting diodes - Google Patents
Alingap light emitting diodes Download PDFInfo
- Publication number
- GB2293488A GB2293488A GB9517879A GB9517879A GB2293488A GB 2293488 A GB2293488 A GB 2293488A GB 9517879 A GB9517879 A GB 9517879A GB 9517879 A GB9517879 A GB 9517879A GB 2293488 A GB2293488 A GB 2293488A
- Authority
- GB
- United Kingdom
- Prior art keywords
- substrate
- light emitting
- semiconductor device
- ingaas
- emitting diodes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000758 substrate Substances 0.000 claims abstract description 24
- 239000004065 semiconductor Substances 0.000 claims description 12
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 claims 6
- 238000001429 visible spectrum Methods 0.000 abstract description 5
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 5
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 3
- 238000001451 molecular beam epitaxy Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 238000000927 vapour-phase epitaxy Methods 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—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
- H01L33/02—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 characterised by the semiconductor bodies
- H01L33/26—Materials of the light emitting region
- H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Led Devices (AREA)
Abstract
Quarternary AlInGaP light emitting diodes grown lattice-matched to an In-0.08Ga-.92As substrate. The diodes exhibit a substantial improvement in light emitting efficiency in the yellow to green portion of the visible spectrum
Description
AlinGaP Light Emitting Diodes
This invention is in the field of semiconductor devices and their fabrication. In particular it relates to fabricating light emitting diodes ("LEDs") with acceptable light output at shorter wavelengths.
Very high efficiency AlInGaP LEDs are known. Herein, the term "high efficiency" means that a large percentage of the electrical energy applied to the LED is converted into light.
These LEDs are typically grown so that their lattice constant matches that of their GaAs substrate. Metalorganic chemical vapor deposition ("MOCVD") is used to grow these LEDs.
Quaternary AlInGaP switches from being a direct bandgap semiconductor, which generates light efficiently, to an indirect bandgap semiconductor, which generates light very inefficiently, at a composition that corresponds to light emission in the green portion of the visible spectrum. The result is a precipitous drop in the light generation efficiency as the emission wavelength of the LED changes from about 590 nanometers (amber light) to light of shorter wavelengths.
The first embodiment of the present invention comprises quaternary AlInGaP LEDs grown lattice-matched an InOoaGa- 95 An substrate. LEDs grown in this manner experience a cross
over from direct bandgap to indirect bandgap at a slightly
higher energy level than when a GaAs substrate is used. This
small increase in the energy at which the direct to indirect
cross-over occurs results in a substantial improvement in the
light emission efficiency in the yellow to green portions of
the visible spectrum.
High quality films of InxGalxAs can be grown on GaAs by
MOCVD, molecular beam epitaxy ("MBE") or hydride vapor phase
epitaxy ("VPE"), especially if the In mole fraction is low.
Such a film could be used as a "pseudo-substrate" if bulk InxGalxAs substrates can not be obtained.
The present invention will now be described in detail with
reference to an exemplary embodiment described with reference to Fig. 1
which is a graph showing the relationship between lattice constant, energy gap
and wavelength of emitted light for a range of III-V materials.
As shown in Fig. 1, the crossover point from a direct bandgap
semiconductor to an indirect semiconductor occurs at a slightly higher energy
gap if quaternary AllnGaP is grown lattice-matched to ln.,,8Ga gAs, as
opposed to pure GaAs. Although the energy gap difference appears small,
any increase in the energy gap at which AlInGaP changes from direct to indirect bandgap results in a large improvement in light emission efficiency in the green to yellow portion of the visible spectrum. The human eye being very color sensitive, moving the emitted light's wavelength from 570 to 560 nanometers results in changing the perceived color from a yellow/green to a deeper green.
Although InxGaXxAs substrates have been produced in bulk substrate form and can be purchased(e.g., from Crystallod Inc.
of Martinsville, N.J.), they are not readily available. High quality films of InxGalxAs can, however, be grown on GaAs by
MOCVD, MBE, or hydride VPE, especially at low In mole fractions. Growing AlInGaP LED structures on In00sGa 92As films or substrates, if available, so that the LEDs and the films or substrates are lattice matched, achieves higher quantum efficiencies in the green-yellow portion of the visible spectrum than in the known art. The lattice constants of the LED structure and the films/substrates should match to within approximately 1%.
The optimum Indium mole fraction x of the InxGalxAs substrate or film is unknown but should be within the 0.04 to 0.12 range. The quality of the material is also important, as high quality films or substrates will perform well near the cross-over point between direct and indirect bandgap semiconductors.
Claims (10)
1. A method for making light emitting diodes comprising the steps of:
growing an InGaAs substrate;
growing an active region comprising at least a first P-N junction from Al InGaP on the InGaAs substrate; and
forming a cathode and anode contact on the substrate and Al InGaP region, respectively.
2. The method of claim 1 wherein the lattice constant of the substrate and the lattice constant of the active region are within about 1% of one another.
3. The method of claim 2 wherein the mole fraction of In in the substrate is between 0.04 and 0.12.
4. The method of claim 3 wherein the InGaAs substrate is an InGaAs film.
5. A semiconductor device comprising:
an InGaAs substrate; and
an AllnGaP active region.
6. The semiconductor device of claim 5 wherein the lattice constant of the substrate and the lattice constant of the active region are matched to within 1%.
7. The semiconductor device of claim 6 wherein the mole fraction of In in the substrate is between 0.04 and 0.12.
8. The semiconductor device of claim 7 wherein the substrate comprises an InGaAs ilm.
9. The semiconductor device of any of claims 5 to 8 wherein the device is a light emitting diode.
10. The semiconductor device of claim 9 wherein the substrate comprises
In0.08Ga0.92As .
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US30935094A | 1994-09-20 | 1994-09-20 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9517879D0 GB9517879D0 (en) | 1995-11-01 |
| GB2293488A true GB2293488A (en) | 1996-03-27 |
Family
ID=23197856
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9517879A Withdrawn GB2293488A (en) | 1994-09-20 | 1995-09-01 | Alingap light emitting diodes |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH08306957A (en) |
| GB (1) | GB2293488A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7244630B2 (en) | 2005-04-05 | 2007-07-17 | Philips Lumileds Lighting Company, Llc | A1InGaP LED having reduced temperature dependence |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002043696A (en) * | 2000-07-26 | 2002-02-08 | Fujitsu Ltd | Semiconductor laser device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0416128A1 (en) * | 1989-03-17 | 1991-03-13 | Sumitomo Electric Industries Limited | Wafer of compound semiconductor |
-
1995
- 1995-09-01 GB GB9517879A patent/GB2293488A/en not_active Withdrawn
- 1995-09-20 JP JP26623395A patent/JPH08306957A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0416128A1 (en) * | 1989-03-17 | 1991-03-13 | Sumitomo Electric Industries Limited | Wafer of compound semiconductor |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7244630B2 (en) | 2005-04-05 | 2007-07-17 | Philips Lumileds Lighting Company, Llc | A1InGaP LED having reduced temperature dependence |
| EP1869716A1 (en) * | 2005-04-05 | 2007-12-26 | LumiLeds Lighting U.S., LLC | Allngap led having reduced temperature dependence |
| US7544525B2 (en) | 2005-04-05 | 2009-06-09 | Philips Lumileds Lighting Co., Llc | AllnGaP LED having reduced temperature dependence |
| US7863631B2 (en) | 2005-04-05 | 2011-01-04 | Koninklijke Philips Electronics N.V. | A1InGaP LED having reduced temperature dependence |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08306957A (en) | 1996-11-22 |
| GB9517879D0 (en) | 1995-11-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |