MIS contact structure with metal oxide conductor
An electrical contact structure (an MIS contact) includes one or more conductors (M-Layer), a semiconductor (S-Layer), and an interfacial dielectric layer (I-Layer) of less than 4 nm thickness disposed between and in contact with both the M-Layer and the S-Layer. The I-Layer is an oxide of a metal or a semiconductor. The conductor of the M-Layer that is adjacent to and in direct contact with the I-Layer is a metal oxide that is electrically conductive, chemically stable and unreactive at its interface with the I-Layer at temperatures up to 450° C. The electrical contact structure has a specific contact resistivity of less than or equal to approximately 10 −5 -10 −7 Ω-cm 2 when the doping in the semiconductor adjacent the MIS contact is greater than approximately 2×10 19 cm −3 and less than approximately 10 −8 Ω-cm 2 when the doping in the semiconductor adjacent the MIS contact is greater than approximately 10 20 cm −3 .
1. An electrical junction structure, comprising a conductor; a semiconductor layer; and an interfacial dielectric layer disposed between and in contact with both the conductor and the semiconductor layer, wherein the conductor is a conductive metal oxide and the interfacial dielectric layer comprises a metal oxide and modifies a Schottky barrier height of the electrical junction structure relative to a barrier height of the electrical junction structure that would occur in the absence of the interfacial dielectric layer.
2. The electrical junction structure of claim 1 , wherein an interface between the conductor and the interfacial dielectric layer is a thermally stable interface up to a temperature of 450° C.
3. The electrical junction structure of claim 2 , wherein the interfacial dielectric layer has a thickness in the range 0.2 nm to 4 nm and comprises one of: WO 3 , TiO 2 , MgO, Al 2 O 3 , HfO 2 , ZrO 2 , Ta 2 O 5 , V 2 O 5 , BaZrO 3 , La 2 O 3 , Y 2 O 3 , HfSiO 4 , ZrSiO 4 , CoO, NiO, GaO, SrTiO 3 , (Ba,Sr)TiO 3 , ZnO, silicon oxide, and germanium oxide, or any of their doped or non-stochiometric variants.
4. The electrical junction structure of claim 2 , wherein the conductive metal oxide has a thickness in the range 0.5 nm to 3 nm and comprises one of: WO 2 , (Nb,Sr)TiO 3 , (Ba,Sr)TiO 3 , SrRuO 3 , MoO 2 , OsO 2 , RhO 2 , RuO 2 , IrO 2 , ReO 3 , ReO 2 , LaCuO 3 , Ti 2 O 3 , TiO, V 2 O 3 , VO, Fe 3 O 4 , ZnO, indium tin oxide (ITO), aluminum-doped zinc-oxide (AZO), InSnO, and CrO 2 , or any of their doped or non-stochiometric variants.
5. The electrical junction structure of claim 2 , wherein the semiconductor layer is a III-V compound semiconductor.
6. The electrical contact structure of claim 2 , wherein the semiconductor layer is a semiconductor comprising one or several of the group IV elements silicon, germanium, carbon, tin, or carbon nanotubes.
7. The electrical junction structure of claim 2 , wherein the semiconductor layer is a doped n-type semiconductor.
8. The electrical junction structure of claim 7 , wherein the interfacial dielectric layer is V 2 O 5 with a thickness of between 0.2 nm and 3.0 nm, and the conductive metal oxide is conductive vanadium oxide with a composition intermediate between VO and VO 2 and a thickness of between 0.5 nm and 5.0 nm.
9. The electrical junction structure of claim 7 , wherein the interfacial dielectric layer is TiO 2 with a thickness of between 0.2 nm and 3.0 nm, and the conductive metal oxide is conductive tungsten oxide with a thickness of between 0.5 nm and 5.0 nm.
10. The electrical junction structure of claim 2 , wherein the interfacial dielectric layer is less than 10 nm thick.
11. The electrical junction structure of claim 10 , wherein the interfacial dielectric layer comprises a plurality of oxide layers, one of which is the metal oxide.
12. The electrical junction structure of claim 11 , wherein the interfacial dielectric layer comprises at least one of: WO 3 , TiO 2 , MgO, Al 2 O 3 , HfO 2 , ZrO 2 , Ta 2 O 5 , V 2 O 5 , BaZrO 3 , La 2 O 3 , Y 2 O 3 , HfSiO 4 , ZrSiO 4 , CoO, NiO, GaO, SrTiO 3 , and (Ba,Sr)TiO 3 .
13. The electrical junction structure of claim 11 , wherein the conductive metal oxide comprises at least one of: WO 2 , (Nb,Sr)TiO 3 , (Ba,Sr)TiO 3 , SrRuO 3 , MoO 2 , OsO 2 , RhO 2 , RuO 2 , IrO 2 , ReO 3 , ReO 2 , LaCuO 3 , Ti 2 O 3 , TiO, V 203 , VO, Fe 3 O 4 , ZnO, indium tin oxide (ITO), aluminum-doped zinc-oxide (AZO), InSnO, and CrO 2 .
14. The electrical junction structure of claim 11 , wherein the semiconductor layer is a III-V compound semiconductor.
15. The electrical contact structure of claim 11 , wherein the semiconductor layer is a semiconductor comprising one or several of the group IV elements silicon, germanium, carbon, or tin.
16. The electrical junction structure of claim 11 , wherein the semiconductor layer is a doped n-type semiconductor.
17. The electrical junction structure of claim 2 , wherein the conductor comprises a stack of metals including at least a first oxide of a first metal, and the metal oxide of the interfacial dielectric layer is a second oxide of the first metal different from the first oxide of the first metal.
18. The electrical junction structure of claim 2 , wherein the metal oxide of the interfacial dielectric layer comprises an oxide of a first metal and the conductive metal oxide conductor comprises an oxide of a second metal.
19. The electrical junction structure of claim 2 , wherein interfacial dielectric layer comprises a plurality of oxides, one of which is the metal oxide and another of which comprises a material that would be an insulator or a semiconductor in its bulk state.
20. The electrical junction structure of claim 2 , wherein the interfacial dielectric layer comprises at least one of titanium silicate, TiSi x O y , or titanium silicon oxynitride.
21. The electrical junction structure of claim 2 , wherein the interfacial dielectric layer comprises the metal oxide and an oxide of a semiconductor.
22. The electrical junction structure of claim 21 , wherein the metal oxide comprises Al 2 O 3 , and the oxide of the semiconductor comprises an oxide of silicon.
23. The electrical junction of claim 22 , wherein the semiconductor layer is a doped n-type semiconductor.
24. The electrical junction of claim 22 , wherein the semiconductor layer is a doped p-type semiconductor.
25. The electrical junction structure of claim 21 , wherein the metal oxide comprises TiO 2 , and the oxide of the semiconductor comprises an oxide of silicon.
26. The electrical junction of claim 25 , wherein the semiconductor layer is a doped n-type semiconductor.
27. The electrical junction of claim 25 , wherein the semiconductor layer is a doped p-type semiconductor.
28. The electrical junction structure of claim 2 , wherein the conductive metal oxide comprises an oxide of multiple different metals.
29. The electrical junction structure of claim 2 , wherein the conductive metal oxide comprises an oxide of iron.
30. The electrical junction structure of claim 2 , wherein the electrical junction includes an oxide of nickel.