Method for the formation of nano-scale on-chip optical waveguide structures
A strip of sacrificial semiconductor material is formed on top of a non-sacrificial semiconductor material substrate layer. A conformal layer of the non-sacrificial semiconductor material is epitaxially grown to cover the substrate layer and the strip of sacrificial semiconductor material. An etch is performed to selectively remove the strip of sacrificial semiconductor material and leave a hollow channel surrounded by the conformal layer and the substrate layer. Using an anneal, the conformal layer and the substrate layer are reflowed to produce an optical waveguide structure including the hollow channel.
1. An optical waveguide, comprising:
a supporting substrate including a layer of insulating material having a top surface; and
a layer of semiconductor material having a bottom surface in contact with the top surface of the layer of insulating material, said layer of semiconductor material including at least one hollow optical channel contained within the layer of semiconductor material and extending with a length parallel to the top surface of the layer of insulating material, said layer of semiconductor material further having a non-planar top surface including first substantially planar top surface portions on either side of the at least one hollow optical channel and a second curved top surface extending over the at least one hollow optical channel, wherein a lowest portion of an inner surface of the at least one hollow optical channel is positioned below the first substantially planar top surface portions of said layer of semiconductor material.
2. The optical waveguide of claim 1 , wherein said at least one hollow optical channel has a cross-section perpendicular to said length that is substantially circular.
3. The optical waveguide of claim 1 , wherein the lowest portion of the inner surface of the at least one hollow optical channel is positioned above the top surface of the layer of insulating material.
4. The optical waveguide of claim 1 , wherein a highest portion of the inner surface of the at least one hollow optical channel is positioned above the first substantially planar top surface portions of said layer of semiconductor material.
5. The optical waveguide of claim 4 , wherein the highest portion of the inner surface of the at least one hollow optical channel is positioned below the second curved top surface of said layer of semiconductor material.
6. The optical waveguide of claim 1 , wherein said layer of semiconductor material comprises reflowed silicon.
7. The optical waveguide of claim 1 , wherein said at least one hollow optical channel has a circular cross-section with a diameter in a range between 50 nanometers and hundreds of nanometers.
8. The optical waveguide of claim 1 , wherein the layer of insulating material is an insulator layer of a silicon on insulator substrate.
9. An optical waveguide, comprising:
a layer of semiconductor material having a bottom surface and a top surface;
a hollow optical channel contained within the layer of semiconductor material and extending with a length parallel to the bottom surface;
wherein said top surface comprises first top surface portions on either side of the hollow optical channel and a second curved top surface portion extending over the hollow optical channel;
wherein a lowest portion of an inner surface of the hollow optical channel is positioned below the first top surface portions; and
wherein a highest portion of an inner surface of the hollow optical channel is positioned above the first top surface portions.
10. The optical waveguide of claim 9 , wherein the highest portion of an inner surface of the hollow optical channel is offset from the second curved top surface portion.
11. The optical waveguide of claim 9 , wherein said hollow optical channel has a cross-section perpendicular to said length that is substantially circular.
12. The optical waveguide of claim 11 , wherein the cross-section has a diameter in a range between 50 nanometers and hundreds of nanometers.
13. The optical waveguide of claim 9 , wherein said layer of semiconductor material comprises reflowed silicon.
14. The optical waveguide of claim 9 , wherein said layer of semiconductor material is supported by an insulating substrate layer.
15. An optical waveguide, comprising:
a supporting substrate including a layer of insulating material having a top surface; and
a layer of semiconductor material having a bottom surface in contact with the top surface of the layer of insulating material, said layer of semiconductor material including at least one hollow optical channel contained within the layer of semiconductor material and extending with a length parallel to the top surface of the layer of insulating material, said layer of semiconductor material further having a non-planar top surface including first top surface portions on either side of the at least one hollow optical channel and a second top surface extending over the at least one hollow optical channel, wherein a lowest portion of an inner surface of the at least one hollow optical channel is positioned below the first top surface portions of said layer of semiconductor material.
16. The optical waveguide of claim 15 , wherein said at least one hollow optical channel has a cross-section perpendicular to said length that is substantially circular.
17. The optical waveguide of claim 15 , wherein said layer of semiconductor material comprises reflowed silicon.
18. The optical waveguide of claim 15 , wherein said at least one hollow optical channel has a circular cross-section with a diameter in a range between 50 nanometers and hundreds of nanometers.
19. The optical waveguide of claim 15 , wherein the layer of insulating material is an insulator layer of a silicon on insulator substrate.
20. The optical waveguide of claim 15 , wherein the lowest portion of the inner surface of the at least one hollow optical channel is positioned above the top surface of the layer of insulating material.
21. An optical waveguide, comprising:
a supporting substrate including a layer of insulating material having a top surface; and
a layer of semiconductor material having a bottom surface in contact with the top surface of the layer of insulating material, said layer of semiconductor material including at least one hollow optical channel contained within the layer of semiconductor material and extending with a length parallel to the top surface of the layer of insulating material, said layer of semiconductor material further having a non-planar top surface including first top surface portions on either side of the at least one hollow optical channel and a second top surface extending over the at least one hollow optical channel, wherein a highest portion of the inner surface of the at least one hollow optical channel is positioned above the first top surface portions of said layer of semiconductor material.
22. The optical waveguide of claim 21 , wherein said at least one hollow optical channel has a cross-section perpendicular to said length that is substantially circular.
23. The optical waveguide of claim 21 , wherein said layer of semiconductor material comprises reflowed silicon.
24. The optical waveguide of claim 21 , wherein said at least one hollow optical channel has a circular cross-section with a diameter in a range between 50 nanometers and hundreds of nanometers.
25. The optical waveguide of claim 21 , wherein the layer of insulating material is an insulator layer of a silicon on insulator substrate.
26. The optical waveguide of claim 21 , wherein the highest portion of the inner surface of the at least one hollow optical channel is positioned below the second top surface of said layer of semiconductor material.