Method for depinning the Fermi level of a semiconductor at an electrical junction and devices incorporating such junctions
An electrical device in which an interface layer is disposed between and in contact with a metal and a Si-based semiconductor, the interface layer being of a thickness effective to depin of the Fermi level of the semiconductor while still permitting current to flow between the metal and the semiconductor. The interface layer may include a layer of a passivating material (e.g., made from nitrogen, oxygen, oxynitride, arsenic, hydrogen and/or fluorine) and sometimes also includes a separation layer. In some cases, the interface layer may be a monolayer of a semiconductor passivating material. The interface layer thickness corresponds to a minimum specific contact resistance of less than or equal to 10 Ω-μm 2 or even less than or equal to 1 Ω-μm 2 for the electrical device.
1. An electrical device, comprising:
a metal;
a silicon-based semiconductor; and
an interface layer of less than 1 nm thickness in a vicinity disposed between and in contact with both the metal and the semiconductor and configured to depin a Fermi level of the metal,
wherein the electrical device has a specific contact resistance of less than or equal to approximately 1000 Ω-μm 2 .
2. The electrical device of claim 1 wherein the interface layer includes a passivating material.
3. The electrical device of claim 2 wherein the passivating material comprises one or more of a nitride, a fluoride, an oxide, an oxynitride, a hydride and/or an arsenide of silicon.
4. The electrical device of claim 3 wherein the interface layer consists essentially of a monolayer.
5. The electrical device of claim 2 wherein the interface layer further includes a separation layer.
6. The electrical device of claim 1 wherein the specific contact resistance is less than or equal to approximately 100 Ω-μm 2 .
7. The electrical device of claim 1 wherein the specific contact resistance is less than or equal to approximately 50 Ω-μm 2 .
8. The electrical device of claim 1 wherein the specific contact resistance is less than or equal to approximately 10 Ω-μm 2 .
9. The electrical device of claim 1 wherein the specific contact resistance is less than or equal to approximately 1 Ω-μm 2 .
10. The electrical device of claim 1 wherein the interface layer comprises a passivation layer fabricated by heating the semiconductor in the presence of nitrogenous material.
11. The electrical device of claim 10 wherein the nitrogenous material comprises at least one of ammonia (NH 3 ), nitrogen (N 2 ) or unbound nitrogen (N).
12. An electrical device, comprising a metal—interface layer—Si-based semiconductor junction in which the interface layer is less than 1 nm thick in a vicinity of the junction and includes a passivating material and the electrical device has a specific contact resistance of less than approximately 1000 Ω-μm 2 .
13. The electrical device of claim 12 wherein the specific contact resistance is less than or equal to approximately 100 Ω-μm 2 .
14. The electrical device of claim 12 wherein the specific contact resistance is less than or equal to approximately 50 Ω-μm 2 .
15. The electrical device of claim 12 wherein the specific contact resistance is less than or equal to approximately 10 Ω-μm 2 .
16. The electrical device of claim 1 wherein the specific contact resistance is less than or equal to approximately 1 Ω-μm 2 .
17. The electrical device of claim 12 , wherein the passivating material comprises one or more of a nitride, an oxide, an oxynitride a hydride, a fluoride and/or an arsenide of silicon.
18. The electrical device of claim 17 , wherein the interface layer comprises a passivation layer and a separation layer.
19. A method, comprising depinning a Fermi level of a conductor in an electrical junction with a silicon-based semiconductor through the use of an interface layer disposed between a surface of the semiconductor and the conductor, wherein the interface layer (i) has a thickness of less than 1 nm in a vicinity of the junction yet sufficient to reduce effects of metal-induced gap states in the semiconductor while providing the junction with a specific contact resistance of less than approximately 1000 Ω-μm 2 , and (ii) passivates the surface of the semiconductor.
20. The method of claim 19 wherein the specific contact resistance is less than or equal to approximately 100 Ω-μM 2 .
21. The method of claim 19 wherein the specific contact resistance is less than or equal to approximately 50 Ω-μm 2 .
22. The method of claim 19 wherein the specific contact resistance is less than or equal to approximately 10 Ω-μm 2 .
23. The method of claim 19 wherein the specific contact resistance is less than or equal to approximately 1 Ω-μM 2 .
24. The method of claim 19 wherein the interface layer has a thickness sufficient to provide a specific contact resistance of the electrical junction of less than or equal to approximately 1 Ω-μm 2 .
25. The method of claim 19 wherein the interface layer includes a passivating material selected from the list comprising: an arsenide, a hydride, a fluoride, an oxide, an oxynitride and a nitride of silicon.
26. The method of claim 25 wherein the interface layer consists essentially of a monolayer.
27. The method of claim 19 wherein the interface layer is grown on the semiconductor surface at temperatures above approximately 300° C.
28. The method of claim 27 wherein the interface layer is grown in the presence of a nitrogenous material.
29. The method of claim 28 wherein the nitrogenous material comprises one of ammonia (NH 3 ), nitrogen (N 2 ), or unbound nitrogen (N).
30. The method of claim 19 wherein the interface layer includes a passivation layer grown by immersion of the semiconductor in a liquid containing hydrogen and fluorine ions.
31. An electrical device, comprising a junction between a Si-based semiconductor and a conductor separated from the semiconductor by an interface layer having a thickness of less than 1 nm in a vicinity of the junction yet that allows a Fermi level of the conductor to align with a conduction band of the semiconductor, wherein the electrical device has a specific contact resistance less than approximately 1000 Ω-μm 2 .
32. The electrical device of claim 31 wherein the specific contact resistance is less than or equal to approximately 100 Ω-μm 2 .
33. The electrical device of claim 31 wherein the specific contact resistance is less than or equal to approximately 50 Ω-μm 2 .
34. The electrical device of claim 31 wherein the specific contact resistance is less than or equal to approximately 10 Ω-μm 2 .
35. The electrical device of claim 31 wherein the specific contact resistance is less than or equal to approximately 1 Ω-μm 2 .
36. An electrical device, comprising a junction between a Si-based semiconductor and a conductor separated from the semiconductor by an interface layer having a thickness of less than 1 nm in a vicinity of the junction yet that allows a Fermi level of the conductor to align with a valence band of the semiconductor, wherein the electrical device has a specific contact resistance less than approximately 1000 Ω-μm 2 .
37. The electrical device of claim 36 wherein the specific contact resistance is less than or equal to approximately 100 Ω-μm 2 .
38. The electrical device of claim 36 wherein the specific contact resistance is less than or equal to approximately 50 Ω-μm 2 .
39. The electrical device of claim 36 wherein the specific contact resistance is less than or equal to approximately 10 Ω-μm 2 .
40. The electrical device of claim 36 wherein the specific contact resistance is less than or equal to approximately 1 Ω-μm 2 .
41. An electrical device, comprising a junction between a Si-based semiconductor and a conductor separated from the semiconductor by an interface layer having a thickness of less than 1 nm in a vicinity of the junction yet that allows a Fermi level of the semiconductor to be independent of a Fermi level of the conductor, wherein the electrical device has a specific contact resistance less than approximately 1000 Ω-μm 2 .
42. The electrical device of claim 41 wherein the specific contact resistance is less than or equal to approximately 100 Ω-μm 2 .
43. The electrical device of claim 41 wherein the specific contact resistance is less than or equal to approximately 50 Ω-μm 2 .
44. The electrical device of claim 41 wherein the specific contact resistance is less than or equal to approximately 10 Ω-μm 2 .
45. The electrical device of claim 41 wherein the specific contact resistance is less than or equal to approximately 1 Ω-μm 2 .
46. An electrical device, comprising:
a silicon-based semiconductor of either n-type or p-type semiconductor material;
a metal having a workfunction approximately equal to a conduction band of the semiconductor if the semiconductor is of n-type semiconductor material or having a workfunction approximately equal to a valence band of the semiconductor if the semiconductor is of p-type semiconductor material; and
an interface layer of less than 1 nm thickness in a vicinity disposed between and in contact with both the semiconductor and the metal, wherein the electrical device has a specific contact resistance of less than or approximately equal to 1000 Ω-μ 2 .
47. The electrical device of claim 46 wherein the interface layer includes a passivating material.
48. The electrical device of claim 47 wherein the passivating material comprises one or more of a nitride, a fluoride, an oxide, an oxynitride, a hydride and/or an arsenide of silicon.
49. The electrical device of claim 48 wherein the interface layer consists essentially of a monolayer.
50. The electrical device of claim 47 wherein the interface layer further includes a separation layer.
51. The electrical device of claim 46 wherein the specific contact resistance is less than or equal to approximately 100 Ω-μm 2 .
52. The electrical device of claim 46 wherein the specific contact resistance is less than or equal to approximately 50 Ω-μm 2 .
53. The electrical device of claim 46 wherein the specific contact resistance is less than or equal to approximately 10 Ω-μm 2 .
54. The electrical device of claim 46 wherein the specific contact resistance is less than or equal to approximately 1 Ω-μm 2 .
55. The electrical device of claim 46 wherein the interface layer comprises a passivation layer fabricated by heating the semiconductor in the presence of nitrogenous material.
56. The electrical device of claim 55 wherein the nitrogenous material comprises at least one of ammonia (NH 3 ), nitrogen (N 2 ) or unbound nitrogen (N).
57. An electrical device, comprising:
a silicon-based semiconductor of either n-type or p-type semiconductor material;
a metal having a workfunction near or substantially equal to a conduction band edge of the semiconductor if the semiconductor is of p-type semiconductor material, or having a workfunction near or substantially equal to a valence band edge of the semiconductor if the semiconductor is of n-type semiconductor material; and
an interface layer of less than 1 nm thickness in a vicinity disposed between and in contact with both the semiconductor and the metal and configured to depin a Fermi level of the metal.
58. The electrical device of claim 57 wherein the interface layer includes a passivating material.
59. The electrical device of claim 58 wherein the passivating material comprises one or more of a nitride, a fluoride, an oxide, an oxynitride, a hydride and/or an arsenide of silicon.
60. The electrical device of claim 57 wherein the interface layer consists essentially of a monolayer.
61. The electrical device of claim 57 wherein the interface layer further includes a separation layer.
62. An electrical device, comprising a junction between a Si-based semiconductor and a conductor separated from the semiconductor by an interface layer having a thickness sufficient to depin a Fermi level of the conductor in a vicinity of the junction yet thin enough to provide the junction with a specific contact resistance that is generally dependent on the workfunction of the conductor.
63. The electrical device of claim 62 wherein the interface layer includes a passivating material.
64. The electrical device of claim 63 wherein the passivating material comprises one or more of a nitride, a fluoride, an oxide, an oxynitride, a hydride and/or an arsenide of silicon.
65. The electrical device of claim 63 wherein the interface layer consists essentially of a monolayer.
66. The electrical device of claim 63 wherein the interface layer further includes a separation layer.
67. The electrical device of claim 62 wherein the interface layer comprises a passivation the semiconductor in the presence of nitrogenous material.
68. The electrical device of claim 67 wherein the nitrogenous material comprises one of: ammonia (NH 3 ), nitrogen (N 2 ), or unbound nitrogen (N).
69. The electrical device of claim 62 wherein the interface layer includes a passivation layer grown by immersion of the semiconductor in a liquid containing hydrogen and fluorine ions.