High-quality, single-crystalline silicon-germanium films
High-quality, single-crystalline silicon-germanium (Si (1-x) Ge x ) having a high germanium content is provided. Layers of the high-quality, single-crystalline silicon-germanium can be grown to high sub-critical thicknesses and then released from their growth substrates to provide Si (1-x) Ge x films without lattice mismatch-induced misfit dislocations or a mosaic distribution of crystallographic orientations.
1. Single-crystalline silicon-germanium comprising a layer of single-crystalline Si (1-x) Ge x , where 0.4≤x<1, having a thickness of at least 40 nm, wherein the single-crystalline Si (1-x) Ge x does not comprise a mosaic distribution of crystallographic orientations and the single-crystalline silicon-germanium is not bonded to a layer of silicon with which it forms an epitaxial interface.
2. The single-crystalline silicon-germanium of claim 1 , wherein the layer of single-crystalline Si (1-x) Ge x is unstrained.
3. Single-crystalline silicon-germanium comprising a layer of single-crystalline Si (1-x) Ge x , where 0.4≤x<1, having a thickness of at least 40 nm, wherein the single-crystalline Si (1-x) Ge x does not comprise a mosaic distribution of crystallographic orientations and the layer of unstrained, single-crystalline Si (1-x) Ge x is a free-standing layer.
4. The single-crystalline silicon-germanium of claim 2 , wherein the unstrained layer of single-crystalline Si (1-x) Ge x is bonded to a host substrate at a non-epitaxial interface.
5. The single-crystalline silicon-germanium of claim 1 , wherein the layer of single-crystalline Si (1-x) Ge x is strained.
6. The single-crystalline silicon-germanium of claim 5 , wherein the strained layer of single-crystalline Si (1-x) Ge x is bonded to a host substrate at a non-epitaxial interface that prevents the strain in the layer of single-crystalline Si (1-x) Ge x from relaxing.
7. The single-crystalline silicon-germanium of claim 5 , wherein the strained layer of single-crystalline Si (1-x) Ge x is joined with a layer of a second semiconductor at an epitaxial interface, wherein elastic strain is shared between the layer of single-crystalline Si (1-x) Ge x and the layer of the second semiconductor.
8. The single-crystalline silicon-germanium of claim 7 , wherein the second semiconductor is a Group III-V semiconductor.
9. The single-crystalline silicon-germanium of claim 8 , wherein the Group III-V semiconductor is GaAs.
10. The single-crystalline silicon-germanium of claim 8 , wherein the Group III-V semiconductor is GaInP.
11. The single-crystalline silicon-germanium of claim 1 , wherein the layer has a thickness of at least 50 nm.
12. The single-crystalline silicon-germanium of claim 1 , wherein the layer has a thickness of at least 100 nm.
13. The single-crystalline silicon-germanium of claim 1 , wherein the layer has a thickness of at least 500 nm.
14. The single-crystalline silicon-germanium of claim 1 , wherein x≥0.5.
15. The single-crystalline silicon-germanium of claim 1 , wherein x≥0.8.
16. The single-crystalline silicon-germanium of claim 1 , wherein the layer of single-crystalline Si (1-x) Ge x has an area of at least 1 mm 2 .
17. The single-crystalline silicon-germanium of claim 1 , wherein the layer of single-crystalline Si (1-x) Ge x has an area of at least 10 mm 2 .
18. The single-crystalline silicon-germanium of claim 1 , wherein the layer of single-crystalline Si (1-x) Ge x has a thickness in the range from 50 nm to 10 μm.
19. The single-crystalline silicon-germanium of claim 1 , wherein the layer of single-crystalline Si (1-x) Ge x has an rms surface roughness of no greater than 2 nm.
20. The single-crystalline silicon-germanium of claim 1 , wherein the layer of single-crystalline Si (1-x) Ge x has an rms surface roughness of no greater than 1 nm.
21. An electronic device comprising:
a first electrode;
a second electrode; and
a layer of single-crystalline Si (1-x) Ge x , where 0.4≤x<1, in electrical communication with the first electrode and the second electrode, the layer of single-crystalline Si (1-x) Ge x having a thickness of at least 40 nm, wherein the single-crystalline Si (1-x) Ge x does not comprise a mosaic distribution of crystallographic orientations and the single-crystalline silicon-germanium is not bonded to a layer of silicon with which it forms an epitaxial interface.
22. Single-crystalline silicon-germanium comprising a layer of single-crystalline Si (1-x) Ge x , where 0.4≤x<1, having a thickness of at least 40 nm, wherein the single-crystalline Si (1-x) Ge x does not comprise a mosaic distribution of crystallographic orientations, and further wherein the layer of single-crystalline Si (1-x) Ge x forms at least one epitaxial interface with another semiconductor and the concentration of lattice mismatch-induced misfit dislocations at the at least one epitaxial interface is no greater than 1×10 5 cm −2 .
23. The single-crystalline silicon-germanium of claim 22 , wherein the concentration of lattice mismatch-induced misfit dislocations at the at least one epitaxial interface is no greater than 1×10 3 cm −2 .
24. The single-crystal silicon-germanium of claim 22 , wherein the at least one epitaxial interface is free of lattice mismatch-induced misfit dislocations.