Method of growing composite substrate using a relaxed strained layer
View Patent ↗A method according to embodiments of the invention includes providing an epitaxial structure comprising a donor layer and a strained layer. The epitaxial structure is treated to cause the strained layer to relax. Relaxation of the strained layer causes an in-plane lattice constant of the donor layer to change.
1. A method comprising:
providing an epitaxial structure comprising:
a donor layer; and
a strained layer;
treating the epitaxial structure to cause the strained layer to relax, wherein relaxation of the strained layer causes an in-plane lattice constant of the donor layer to change such that the donor layer becomes a seed layer;
removing the strained layer from the seed layer; and
growing a semiconductor structure on the seed layer after removing the strained layer.
2. The method of claim 1 wherein the epitaxial structure further comprises a relaxed layer disposed between the donor layer and the strained layer.
3. The method of claim 2 wherein the epitaxial structure further comprises a second relaxed layer disposed between the donor layer and the strained layer.
4. The method of claim 2 wherein the relaxed layer comprises aluminum.
5. The method of claim 1 wherein the providing of the epitaxial structure comprises growing the epitaxial structure on a first substrate, the method further comprising:
connecting the epitaxial structure to a second substrate; and
removing the first substrate after the connecting.
6. The method of claim 5 wherein:
the epitaxial structure is connected to the second substrate through a bonding layer; and
the treating of the epitaxial structure comprises heating the bonding layer.
7. The method of claim 5 further comprising:
connecting the seed layer to a third substrate; and
removing the strained layer after connecting the seed layer to the third substrate.
8. The method of claim 1 wherein strain in the strained layer is at least as great as strain in the donor layer.
9. The method of claim 1 wherein:
the donor layer is InGaN or GaN;
the strained layer is AlGaN or GaN; and
the epitaxial structure further comprises a relaxed layer disposed between the donor layer and the strained layer, wherein the relaxed layer comprises aluminum.
10. The method of claim 1 , wherein after treating, the seed layer has an in-plane lattice constant of at least 3.2 A.
11. The method of claim 1 , wherein the semiconductor structure includes a light emitting layer disposed between an n-type region and a p-type region on the seed layer.
12. The method of claim 1 wherein:
prior to the treating of the epitaxial structure, the donor layer is in compression; and
the treating comprises causing the in-plane lattice constant of the donor layer to increase such that after treating, the seed layer is at least partially relaxed.
13. The method of claim 1 wherein:
prior to the treating of the epitaxial structure, the donor layer is relaxed; and
the treating comprises causing the in-plane lattice constant of the donor layer to increase such that after treating, the seed layer is in tension.
14. The method of claim 1 wherein prior to the treating of the epitaxial structure, the strained layer is in compression.
15. The method of claim 1 wherein prior to the treating of the epitaxial structure, strain in the strained layer is at least 0.1%.
16. The method of claim 1 , wherein the strained layer has a thickness between 100 nm and 20 microns.
17. The method of claim 1 , wherein the strained layer has a thickness between 1 and 5 microns.
18. The method of claim 1 , wherein the strained layer has a compressive strain of at least 0.1%.
19. A method comprising:
providing an epitaxial structure comprising:
a donor layer, wherein the donor layer is a material on which a semiconductor structure may be grown; and
a strained layer; and
treating the epitaxial structure to cause the strained layer to relax, wherein relaxation of the strained layer causes an in-plane lattice constant of the donor layer to change;
wherein the epitaxial structure further comprises a relaxed layer disposed between the donor layer and the strained layer, and a cap layer disposed between the donor layer and the strained layer, wherein the cap layer is configured to reduce or prevent desorption from the donor layer.
20. A method comprising:
providing an epitaxial structure comprising:
a donor layer, wherein the donor layer is a material on which a semiconductor structure may be grown; and
a strained layer;
treating the epitaxial structure to cause the strained layer to relax, wherein relaxation of the strained layer causes an in-plane lattice constant of the donor layer to change such that the donor layer becomes a seed layer;
connecting the seed layer to a third substrate; and
removing the strained layer from the seed layer;
wherein:
the epitaxial structure further comprises a low band gap layer disposed between the seed layer and the strained layer,
the low band gap layer has a band gap lower than band gaps of the seed
layer and the strained layer; and
the removing of the strained layer comprises melting the low band gap layer with a laser.