Growth structure under a release layer for manufacturing of optoelectronic devices
A growth structure having a lattice transition under a release layer is used as a seed crystal for growth of optoelectronic devices. The optoelectronic device can be a single- or multi-junction photovoltaic device. The release layer can be selectively removed in an epitaxial lift-off (ELO) process to separate the optoelectronic device from the growth structure and leave the region with the lattice transition intact to reuse the growth structure to grow additional devices. A manufacturing method is described that includes providing a growth structure having a substrate and a lattice transition from a first lattice constant to a second lattice constant, depositing a release layer on the growth structure, depositing on the release layer an epitaxial layer having a lattice constant that matches the second lattice and including an optoelectronic device, and removing the release layer to separate the epitaxial layer and the optoelectronic device from the growth structure.
1. A method of manufacturing an optoelectronic device, the method comprising:
providing a growth structure having a substrate, a graded layer that provides a lattice transition from a first lattice constant to a second lattice constant, and a buffer layer disposed over the graded layer, wherein the buffer layer has a buffer lattice constant that matches or is near the second lattice constant of the growth structure;
depositing a release layer over the buffer layer, wherein the release layer has a release lattice constant that matches or is near the second lattice constant;
depositing an epitaxial layer on the release layer, the epitaxial layer including the optoelectronic device and having an epitaxial lattice constant that matches or is near the second lattice constant of the growth structure; and
removing the release layer to separate the epitaxial layer with the optoelectronic device from the growth structure.
2. The method of claim 1 , wherein the epitaxial layer includes at least one subcell that forms the optoelectronic device.
3. The method of claim 2 , wherein:
the optoelectronic device is a single-junction photovoltaic device, and
the at least one subcell includes a single subcell.
4. The method of claim 3 , wherein the single subcell is an InGaAs subcell.
5. The method of claim 4 , wherein the first lattice constant is in the range of 5.65 angstroms to 5.66 angstroms and the second lattice constant is in the range of 5.661 angstroms to 5.69 angstroms.
6. The method of claim 2 , wherein:
the optoelectronic device is a double-junction photovoltaic device, and
the at least one subcell includes a first subcell and a second subcell.
7. The method of claim 6 , wherein:
the first subcell is an InGaP subcell or an AlinGaAs subcell positioned closest to the release layer, and
the second subcell is an InGaAs subcell disposed over the first subcell.
8. The method of claim 7 , wherein the first lattice constant is in the range of 5.65 angstroms to 5.66 angstroms and the second lattice constant is in the range of 5.67 angstroms to 5.85 angstroms.
9. The method of claim 2 , wherein:
the optoelectronic device is a triple-junction photovoltaic device, and
the at least one subcell includes a first subcell, a second subcell, and a third subcell.
10. The method of claim 9 , wherein:
the first subcell is an AlInP subcell or an AlInGaP subcell positioned closest to the release layer,
the second subcell is an InGaP subcell or an InGaAsP subcell or an AlInGaAs subcell disposed over the first subcell, and
the third subcell is an InGaAs subcell disposed over the second subcell.
11. The method of claim 10 , wherein the first lattice constant is about 5.655+/−0.005 angstroms or 5.65+/−0.01 angstroms, and the second lattice constant is in the range of 5.661 angstroms to 5.85 angstroms, the second lattice constant being based on a number of junctions in the optoelectronic device.
12. The method of claim 2 , wherein:
the optoelectronic device is a photovoltaic device with more than three junctions, and
the at least one subcell includes more than three subcells.
13. The method of claim 1 , wherein removing the release layer includes attaching a handle to the epitaxial layer.
14. The method of claim 1 , further comprising:
processing the growth structure after removal of the release layer; and
reusing the processed growth structure to manufacture another optoelectronic device.
15. The method of claim 1 , wherein the optoelectronic device is a light-emitting device.
16. The method of claim 1 , wherein the substrate of the growth structure includes a Group III-V material.
17. The method of claim 16 , wherein the III-V material is GaAs.
18. The method of claim 1 , wherein each of the substrate of the growth structure, the lattice transition of the growth structure, the release layer, and the epitaxial layer includes a Group III-V material.
19. The method of claim 1 , wherein the release layer includes an aluminum-containing compound.
20. The method of claim 19 , wherein the aluminum-containing compound is one of AlAs, AlGaAs, AlinGaAs, AlInP, AlInGaP, or AlinAs, and wherein the aluminum-containing is susceptible to etching by hydrofluoric acid (HF).
21. The method of claim 1 , wherein removing the release layer comprises removing the release layer by an epitaxial lift-off (ELO) process.
22. The method of claim 1 , wherein the graded layer is a compositionally graded buffer.
23. The method of claim 22 , wherein the compositionally graded buffer includes InGaAs or InGaP, and wherein the transition from the first lattice constant to the second lattice constant in the compositionally graded buffer is achieved by changing the stoichiometry of the InGaAs or the InGaP.
24. The method of claim 1 , wherein the optoelectronic device is a metamorphic device.
25. The method of claim 1 , wherein the optoelectronic device is an inverted metamorphic device.