Devices having removed aluminum nitride sections
View Patent ↗One or more layers are epitaxially grown on a bulk crystalline AlN substrate. The epitaxial layers include a surface which is the initial surface of epitaxial growth of the epitaxial layers. The AlN substrate is substantially removed over a majority of the initial surface of epitaxial growth.
1. A light emitting device, comprising:
a bulk AlN substrate;
a first heterostructure of the light emitting device grown on the bulk crystalline AlN substrate, the first heterostructure having a first surface, an etch reduction layer, and a second surface, the first surface being an initial surface of heteroepitaxial growth of the light emitting device and a second surface, the first heterostructure comprising an AlGaN etch reduction layer, wherein the etch reduction layer includes the initial surface of heteroepitaxial growth;
a light emitting layer epitaxially grown above the second surface of the first heterostructure; and
a second heterostructure epitaxially grown above the light emitting layer, wherein the bulk crystalline AlN substrate has been substantially removed from the light emitting device over a majority of the initial surface of heteroepitaxial growth leaving a thin AlN layer having an etched surface and wherein a defect density is less than about 10 8 cm −3 throughout a portion of the first heterostructure that is within about 100 nm of the initial surface of heteroepitaxial growth.
2. The light emitting device of claim 1 , wherein the first heterostructure is an n-type heterostructure and the second heterostructure is a p-type heterostructure.
3. The light emitting device of claim 1 , wherein the first heterostructure comprises AlGaN having an aluminum molar fraction less than about 80%.
4. The light emitting device of claim 1 , wherein the etch reduction layer comprises AlGaN having an aluminum molar fraction in a range of about 70% to about 80%.
5. The light emitting device of claim 1 , wherein the first heterostructure, the second heterostructure, and the light emitting layer comprise at least one of AlGaN, InGaN, InN, GaN, and InAlGaN.
6. The light emitting device of claim 1 , wherein the light emitting device is configured to emit light in a wavelength range of about 200 nm to about 365 nm.
7. The light emitting device of claim 1 , wherein the first heterostructure comprises an AlGaN transition region above the bulk AlN substrate which is subsequently removed.
8. The light emitting device of claim 1 , wherein light emitted from the light emitting device travels through the first heterostructure.
9. The light emitting device of claim 1 , wherein light emitted from the light emitting device travels through the second heterostructure.
10. The light emitting device of claim 1 , wherein light is emitted in a direction parallel to the wafer plane.
11. The light emitting device of claim 1 , wherein the initial surface of heteroepitaxial growth is textured.
12. The light emitting device of claim 1 wherein the light emitting device comprises a vertical electrical injection LED.
13. The light emitting device of claim 1 wherein the light emitting device comprises a laser.
14. The light emitting device of claim 13 , wherein electrodes are formed on the initial surface of heteroepitaxial growth.
15. The light emitting device of claim 13 , further comprising a heat sink disposed proximate the second heterostructure.
16. A light emitting device, comprising:
a bulk AlN substrate;
a first epitaxial heterostructure on the bulk AlN substrate and comprising an initial surface of heteroepitaxial growth of the light emitting device and a second surface, the first heterostructure comprising an AlGaN etch stop layer that includes the initial surface of heteroepitaxial growth;
an epitaxial light emitting layer above the second surface of the first hetero structure; and
a second epitaxial heterostructure above the light emitting layer, wherein the device is configured to allow light generated by the light emitting layer in a wavelength range of less than about 365 nm to emerge from the device through the first surface of the first heterostructure, and wherein a defect density is less than about 10 8 cm − 3 throughout a portion of the first heterostructure that is within about 100 nm of the initial surface of epitaxial growth.
17. A light emitting device, comprising:
a bulk AlN substrate;
a first epitaxial heterostructure of the light emitting device on the bulk crystalline AlN substrate, the first heterostructure including an initial surface of heteroepitaxial growth and an AlGaN etch reduction layer that includes the initial surface of heteroepitaxial growth;
an epitaxial light emitting layer above the first heterostructure;
a second epitaxial heterostructure above the light emitting layer, wherein the bulk crystalline AlN substrate has a thin chemically etched thickness of less than about 50 μm and wherein a defect density is less than about 10 8 cm −3 throughout a portion of the first heterostructure that is within about 100 nm of the initial surface of heteroepitaxial growth.
18. The light emitting device of claim 17 , wherein the first heterostructure is an n-type heterostructure and the second heterostructure is a p-type heterostructure.
19. The light emitting device of claim 17 , wherein the first hetero structure, the second heterostructure, and the light emitting layer comprise at least one of AlGaN, InGaN, InN, GaN, and InAlGaN.
20. The light emitting device of claim 17 , wherein the light emitting device is configured to emit light in a wavelength range of about 200 nm to about 365 nm.
21. The light emitting device of claim 17 , wherein the first heterostructure comprises an AlGaN transition region grown on the bulk AlN substrate.
22. The light emitting device of claim 17 , wherein the initial surface of heteroepitaxial growth is textured.
23. The light emitting device of claim 17 , wherein the light emitting device comprises a vertical electrical injection LED.
24. The light emitting device of claim 17 , wherein the light emitting device comprises a laser.
25. The light emitting device of claim 23 , further comprising a heat sink disposed proximate the second heterostructure.
26. A method of forming light emitting device, comprising:
epitaxially growing a first heterostructure of the light emitting device on a bulk crystalline AlN substrate, the first heterostructure having a first surface, an etch reduction layer, and a second surface, the first surface being an initial surface of heteroepitaxial growth of the light emitting device and a second surface, the first heterostructure comprising a lattice strained AlGaN etch reduction layer, wherein the etch reduction layer includes the initial surface of heteroepitaxial growth;
epitaxially growing a light emitting layer above the second surface of the first heterostructure; and
epitaxially growing a second heterostructure emitting grown above the light emitting layer;
substantially removing the bulk crystalline AlN substrate from the light emitting device over a majority of the initial surface of heteroepitaxial growth, substantial removal of the bulk crystalline AlN substrate relaxing the lattice strain and leaving a thin AlN layer having an etched surface and wherein a defect density is less than about 10 8 cm -3 throughout a portion of the first heterostructure that is within about 100 nm of the initial surface of heteroepitaxial growth.
27. The method of claim 26 , wherein the first heterostructure comprises at least one of AlGaN, InGaN, InN, GaN, and InAlGaN.
28. The method of claim 26 , wherein substantially removing the bulk AlN substrate comprises removing the bulk AlN substrate over a majority of the initial surface of epitaxial growth.
29. The method of claim 26 , wherein substantially removing the bulk AlN substrate comprises chemically etching the bulk AlN substrate to a thickness of less than about 50 μm over a majority of the initial surface of heteroepitaxial growth.
30. The method of claim 26 , wherein substantially removing the bulk AlN substrate comprises chemically etching a nitrogen polar face of the bulk AlN substrate using phosphoric acid.
31. The method of claim 26 , wherein growing the first heterostructure on the bulk AlN substrate comprises growing the first heterostructure using metal organic chemical vapor deposition, hydride vapor phase epitaxy, or a combination thereof.