High bandgap III-V alloys for high efficiency optoelectronics

1. An optoelectronic device comprising:

a first device layer comprising an alloy consisting essentially of Al 1-x In x P, 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 10 6 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 y Sn z Ge 1-y-z and a III-V alloy.

4. The optoelectronic device of claim 1 , wherein each step-grade buffer layer comprises Ga 1-y In y As.

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 μm.

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

8. The optoelectronic device of claim 1 , wherein each step-grade buffer layer comprises Si y Sn z Ge 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-y In y P,

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-y In y P layer; and

a p-type doped Al 1-y In y P layer, wherein:

each of the n-type doped Al 1-y In y P layer and the p-type doped Al 1-y In y P layer is disordered;

the first device layer is positioned between the n-type doped Al 1-y In y P layer and the p-type doped Al 1-y In y P 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-y In y P; 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.