Electrode structure having at least two oxide layers and non-volatile memory device having the same
An electrode structure having at least two oxide layers that more reliably switch and operate without the use of additional devices and a non-volatile memory device having the same are provided. The electrode structure may include a lower electrode, a first oxide layer formed on the lower electrode, a second oxide layer formed on the first oxide layer and an upper electrode formed on the second oxide layer wherein at least one of the first and second oxide layers may be formed of a resistance-varying material. The first oxide layer may be formed of an oxide having a variable oxidation state.
1. An electrode structure, comprising:
a lower electrode;
a first oxide layer formed on the lower electrode, wherein the first oxide layer is formed of an oxide having a variable oxidation state;
a second oxide layer formed on the first oxide layer; and
an upper electrode formed on the second oxide layer,
wherein at least one of the first and second oxide layers are formed of a resistance-varying material.
2. The electrode structure of claim 1 , wherein the lower electrode is formed of a metal that forms a schottky contact with the first oxide layer.
3. The electrode structure of claim 2 , wherein metal is at least one selected from the group consisting of platinum (Pt), ruthenium (Ru) and iridium (Ir).
4. The electrode structure of claim 2 , wherein the metal is a metal oxide.
5. The electrode structure of claim 4 , wherein the metal oxide is at least one selected from the group consisting of platinum oxide, a ruthenium oxide and an iridium oxide.
6. The electrode structure of claim 2 , wherein the metal is titanium (Ti) or silver (Ag).
7. The electrode structure of claim 1 , wherein the first oxide layer is formed of a transition metal oxide.
8. The electrode structure of claim 7 , wherein the transition metal oxide is formed of at least one selected from the group consisting of NiO, CeO 2 , VO 2 , V 2 O 5 , Nb 2 O 5 , TiO 2 , Ti 2 O 3 , WO 3 , Ta 2 O 5 and ZrO 2 .
9. The electrode structure of claim 7 , wherein the upper electrode is a metal.
10. The electrode structure of claim 9 , wherein the metal is at least one selected from the group consisting of platinum (Pt), ruthenium (Ru) and iridium (Ir).
11. The electrode structure of claim 9 , wherein the metal is a metal oxide.
12. The electrode structure of claim 11 , wherein the metal oxide is at least one selected from the group consisting of a platinum oxide, a ruthenium oxide and an iridium oxide.
13. The non-volatile memory device of claim 11 , wherein the first oxide layer is formed of a transition metal oxide.
14. The non-volatile memory device of claim 11 , wherein the second oxide layer is formed of an amorphous oxide.
15. The electrode structure of claim 1 , wherein the second oxide layer is formed of an amorphous oxide.
16. The electrode structure of claim 15 , wherein the amorphous oxide is formed of InZnO (IZO) or InSnO (ITO).
17. A non-volatile memory device, comprising:
a substrate including a first and second impurity region;
a gate electrode including a conductive layer and a capping layer sequentially stacked on the substrate and contacting the first and second impurity regions;
an interlayer formed on the gate electrode, the first impurity region and the second impurity region;
a conductive plug formed in the interlayer and contacting one of the first or second impurity regions; and
the electrode structure according to claim 1 formed on the conductive plug and a portion of the interlayer.
18. The non-volatile memory device of claim 17 , wherein the lower electrode is formed of a metal that forms a schottky contact with the first oxide layer.
19. The non-volatile memory device of claim 18 , wherein the metal is a metal oxide.