Thin film semiconductor switching device
Novel semiconductor devices are taught. The novel devices include a thin film transistor (TFT) with an n-type semiconductor layer to form a channel between a source and a drain. The TFT further includes a source-channel interfacial member adjacent to at least the source contact of the device to provide depletion layer control of the operation of the TFT.
1. A thin-film transistor comprising:
a source disposed at a substrate or insulation layer, the source including a source contact;
a drain disposed at the substrate or insulation layer and spaced apart from the source;
an n-type semiconductor layer extending between the source and drain for formation of a carrier channel between the source and drain, the n-type semiconductor layer including tin oxide; and
a source-channel interfacial member positioned between the source contact and the n-type semiconductor layer, the source-channel interfacial member being in contact with the source contact and the n-type semiconductor layer;
wherein the source-channel interfacial member is operable to deplete the carrier channel in a region of the n-type semiconductor layer adjacent the source contact to reduce leakage current when the thin-film transistor is off.
2. The thin-film transistor of claim 1 , wherein the source-channel interfacial member comprises a p-type semiconductor.
3. The thin-film transistor of claim 1 , wherein the source-channel interfacial member comprises a p-type metal oxide.
4. The thin-film transistor of claim 1 , wherein the source-channel interfacial member comprises oxidized material of the source contact.
5. The thin-film transistor of claim 1 , wherein the source-channel interfacial member comprises a layer of material deposited on the source contact.
6. The thin-film transistor of claim 1 , wherein the source contact comprises ruthenium.
7. The thin-film transistor of claim 6 , wherein source-channel interfacial member layer comprises ruthenium oxide.
8. The thin-film transistor of claim 1 , wherein the source contact comprises cobalt.
9. The thin-film transistor of claim 8 , wherein source-channel interfacial member layer comprises cobalt oxide.
10. The thin-film transistor of claim 1 , wherein the n-type semiconductor layer is formed by atomic layer deposition.
11. The thin-film transistor of claim 1 , further comprising:
a gate dielectric layer over the n-type semiconductor layer; and
a gate contact over the gate dielectric layer.
12. The thin-film transistor of claim 11 , wherein the gate dielectric layer comprises hafnium oxide.
13. The thin-film transistor of claim 1 , wherein:
the drain comprises a drain contact; and
the source-channel interfacial member extends between the drain contact and the n-type semiconductor layer, the source-channel interfacial member being in contact with the drain contact.
14. The thin-film transistor of claim 1 , wherein:
the drain comprises a drain contact; and
the thin-film transistor further comprises another channel interfacial member positioned between the drain contact and the n-type semiconductor layer, the other channel interfacial member being in contact with the drain contact and the n-type semiconductor layer.
15. A method of making a thin-film transistor comprising:
forming a source and drain at a substrate or insulation layer, the drain being spaced apart from the source, the source including a source contact;
forming a source-channel interfacial member at the source and in contact with the source contact; and
forming an n-type semiconductor layer between the source and drain and in contact with the source-channel interfacial member, the n-type semiconductor layer including tin oxide;
wherein the source-channel interfacial member is operable to deplete a carrier channel in a region of the n-type semiconductor layer adjacent the source contact to reduce leakage current when the thin-film transistor is off.
16. The method of claim 15 , wherein the source-channel interfacial member comprises a p-type semiconductor.
17. The method of claim 15 , wherein the source-channel interfacial member comprises a p-type metal oxide.
18. The method of claim 15 , wherein forming the source-channel interfacial member comprises oxidizing material of the source contact.
19. The method of claim 15 , wherein forming the source-channel interfacial member comprises forming a layer of material on the source contact.
20. The method of claim 15 , further comprising using atomic layer deposition to form the source-channel interfacial member on the source contact.
21. The method of claim 15 , wherein:
the source contact comprises ruthenium; and
source-channel interfacial member layer comprises ruthenium oxide.
22. The method of claim 15 , wherein:
the source contact comprises cobalt; and
the source-channel interfacial member layer comprises cobalt oxide.
23. The method of claim 15 , wherein forming the n-type semiconductor layer comprises using atomic layer deposition to form the n-type semiconductor layer.
24. The method of claim 15 , further comprising:
forming a gate dielectric layer over the n-type semiconductor layer; and
forming a gate contact over the gate dielectric layer.
25. The method of claim 24 , wherein the gate dielectric layer comprises hafnium oxide.
26. The method of claim 15 , further comprising:
forming the source-channel interfacial member at the drain and in contact with a drain contact.
27. The method of claim 15 , further comprising:
forming another channel interfacial member at the drain and in contact with a drain contact;
wherein n-type semiconductor layer is formed in contact with the other channel interfacial member.
28. A method of making a thin-film transistor comprising:
with a wafer that includes a source and drain positioned at a substrate or insulation layer and a source-channel interfacial member formed in contact with a source contact of the source, using atomic layer deposition to deposit tin oxide to form an n-type semiconductor layer between the source and drain and in contact with the source-channel interfacial member;
wherein the source-channel interfacial member is operable to deplete a carrier channel in a region of the n-type semiconductor layer adjacent the source to reduce leakage current when the thin-film transistor is off.
29. The method of claim 28 , further comprising using atomic layer deposition to form the source-channel interfacial member.
30. The method of claim 28 , further comprising:
using atomic layer deposition to deposit a gate dielectric layer over the n-type semiconductor layer.