High bandgap III-V alloys for high efficiency optoelectronics

• US 9,543,468 B2
• Filed: 10/12/2011
• Issued: 01/10/2017
• Est. Priority Date: 10/12/2010
• Status: Active Grant

• Current Assignee: Alliance For Sustainable Energy LLC
• Original Assignee: Alliance For Sustainable Energy LLC
• Inventors: Alberi, Kirstin, Mascarenhas, Angelo, Wanlass, Mark
• Primary Examiner(s): Ingham, John C
• Assistant Examiner(s): MAZUMDER, DIDARUL A
• Application Number:
  US13/878,738
• Publication Number:
  US 20130221326A1
• Time in Patent Office: 1,917 Days
• Field of Search: 257/13, 438/22
• US Class Current: 1/1
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/0066 with a substrate not being a III-V compound
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/305 characterised by the doping materials

Abstract

High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al_1-xIn_xP layer, and a step-grade buffer between the substrate and at least one Al_1-xIn_xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al_1-xIn_xP is reached.

Claims

1. An optoelectronic device comprising:

a first device layer comprising an alloy consisting essentially of Al_1-xIn_xP, wherein;

0.54≦

x<

1.0,

the first device layer is at least partially ordered, and

the first device layer is configured to emit light;

a substrate comprising at least one of GaAs, Si, Ge, InP, or GaP; and

a first compositionally-graded buffer layer comprising;

a first step-grade buffer layer in contact with the substrate;

a second step-grade buffer layer in contact with the first device layer, and

between one and six additional step-grade buffer layers positioned between the substrate and the first device layer, wherein;

the first step-grade buffer layer is substantially lattice-matched with the substrate,

the second step-grade buffer layer is substantially lattice-matched with the first device layer, and

each additional step-grade buffer layer has a lattice constant that is between the lattice constants of its two immediate closest neighboring step-grade buffer layers.

2. The optoelectronic device of claim 1, wherein the first device layer has a dislocation density less than about 10⁶ cm⁻

2.

3. The optoelectronic device of claim 1, wherein each step-grade buffer layer comprises an alloy selected from the group consisting of Si_ySn_zGe_1-y-z and a III-V alloy.

4. The optoelectronic device of claim 1, wherein each step-grade buffer layer comprises Ga_1-yIn_yAs.

5. The optoelectronic device of claim 4, wherein 0.075≦

y≦

0.225 for the second step-grade buffer layer.

6. The optoelectronic device of claim 5, wherein:

y is 0.075 for the second step grade buffer layer, and

each step-grade buffer layer has a thickness of about 0.5 μ

m.

7. The optoelectronic device of claim 1, wherein each step-grade buffer layer comprises GaBi_yAs_1-y.

8. The optoelectronic device of claim 1, wherein each step-grade buffer layer comprises Si_ySn_zGe_1-y-z.

9. The optoelectronic device of claim 1, wherein the optoelectronic device is a light emitting diode (LED).

10. The optoelectronic device of claim 1, wherein the first device layer comprises a first n-type doped layer and a first p-type doped layer.

11. The optoelectronic device of claim 10, further comprising:

a second n-type doped layer; and

a second p-type doped layer, wherein;

each of the second n-type doped layer and the second p-type doped layer is disordered,

each of the second n-type doped layer and the second p-type doped layer comprises Al_1-yIn_yP,

the first device layer is positioned between the second n-type doped layer and the second p-type doped layer, and

y is less than x.

12. The optoelectronic device of claim 1, further comprising:

an n-type doped Al_1-yIn_yP layer; and

a p-type doped Al_1-yIn_yP layer, wherein;

each of the n-type doped Al_1-yIn_yP layer and the p-type doped Al_1-yIn_yP layer is disordered;

the first device layer is positioned between the n-type doped Al_1-yIn_yP layer and the p-type doped Al_1-yIn_yP layer, and

y is less than x.

13. The optoelectronic device of claim 1, wherein the first device layer is configured to emit light in at least one of green, yellow, orange, or red spectra.

14. The optoelectronic device of claim 1, further comprising a second device layer, wherein each device layer has a composition different than the other device layer.

15. The optoelectronic device of claim 1, further comprising:

a second device layer comprising an alloy consisting essentially of Al_1-yIn_yP; and

a second compositionally-graded buffer layer, wherein;

the second compositionally-graded buffer layer is positioned between the second device layer and the first device layer; and

y is not equal to x.

16. The optoelectronic device of claim 15, wherein the substrate comprises InP.

17. The optoelectronic device of claim 1, wherein 0.54≦

x≦

0.68.

18. The optoelectronic device of claim 1, wherein the light has a wavelength between 540 nm and 590 nm.

19. The optoelectronic device of claim 1, wherein the light is green.

20. The optoelectronic device of claim 1, wherein the first device layer has a lattice constant between 5.68 Å

and 5.74 Å

.