Memristor and neuromorphic device comprising the same
Provided are memristors and neuromorphic devices including the memristors. A memristor includes a lower electrode and an upper electrode that are apart from each other and first and second two-dimensional material layers that are arranged between the lower electrode and the upper electrode and stacked without a chemical bond therebetween.
1. A memristor comprising:
a lower electrode and an upper electrode that are spaced apart from each other; and
a resistance change layer between the lower electrode and the upper electrode, the resistance change layer including only a first two-dimensional material layer and a second two-dimensional material layer that are stacked on each other as a double-layer,
wherein the lower electrode and the upper electrode include different materials from each other, and
wherein the resistance change layer has resistance characteristics that decrease as a number of sweeps of an applied positive electrical signal increases, and increases as a number of sweeps of an applied negative electrical signal increases,
wherein each of the first two-dimensional material layer and the second two-dimensional material layer includes at least one of MoS 2 , WS 2 , MoSe 2 , WSe 2 , MoTe 2 , WTe 2 , ZrS 2 , ZrSe 2 , HfS 2 , HfSe 2 , GaSe, GaTe, InSe, In 2 Se 3 , Bi 2 Se 3 , and black phosphorus.
2. The memristor of claim 1 , wherein the resistance change layer includes defective grain boundaries.
3. The memristor of claim 2 , wherein
the resistance change layer is configured to form a conductive filament on the defective grain boundaries in response to an application of an electrical signal to the lower electrode and the upper electrode.
4. The memristor of claim 2 , wherein each of the first two-dimensional material layer and the second two-dimensional material layer includes line-type defects.
5. The memristor of claim 1 , wherein the resistance change layer includes dot-type defects.
6. The memristor of claim 1 , wherein the memristor is configured to operate with a set voltage in a range that is equal to or higher than 0.1 V and equal to or lower than 0.5 V.
7. The memristor of claim 1 , wherein the memristor is configured to perform a bipolar resistive switching operation.
8. The memristor of claim 1 , wherein, in the memristor after undergoing a forming operation,
an ohmic conduction slope of the memristor in a high resistance state is constant, and
an ohmic conduction slope of the memristor in a low resistance state is constant.
9. The memristor of claim 8 , wherein the ohmic conduction slope of the memristor in the high resistance state, the low resistance state, or both the high resistance state and the low resistance state is in a range of 0.8 to 1.2.
10. The memristor of claim 1 , wherein a distance between the lower electrode and the upper electrode is two to ten times a size of atoms in the resistance change layer.
11. The memristor of claim 1 , wherein the first two-dimensional material laver and the second two-dimensional material include a same material.
12. The memristor of claim 1 , wherein the first two-dimensional material layer and the second two-dimensional material layer have semiconductor characteristics.
13. The memristor of claim 1 , wherein each of the first two-dimensional material layer and the second two-dimensional material layer is a single layer.
14. The memristor of claim 1 , wherein at least one of the lower electrode and the upper electrode includes a metal.
15. The memristor of claim 1 , wherein
the first two-dimensional material layer directly contacts the lower electrode and the second two-dimensional material layer, and
the second two-dimensional material layer directly contacts the upper electrode.
16. The memristor of claim 1 , wherein
one of the lower electrode and the upper electrode includes an active electrode, and
an other of the lower electrode and the upper electrode includes a non-active electrode.
17. The memristor of claim 1 , wherein the resistance change layer is arranged in an area where the lower electrode and the upper electrode overlap each other.
18. The memristor of claim 1 , wherein the upper electrode, the first two-dimensional material layer, the second two-dimensional material layer, and the lower electrode are sequentially arranged to contact each other.
19. The memristor of claim 1 , wherein
the upper electrode includes a plurality of first electrodes that are spaced apart from each other in a first direction perpendicular to a thickness direction of the resistance change layer,
the lower electrode includes a plurality of second electrodes that are spaced apart from each other in a second direction that is perpendicular to the thickness direction of the resistance change layer, and
the second direction is different than the first direction.
20. The memristor of claim 19 , wherein
the resistance change layer includes a plurality of sub-resistance change layers that are arranged in an area where the plurality of first electrodes and the plurality of second electrodes overlap with each other, and
the plurality of sub-resistance change layers are spaced apart from each other.
21. A device comprising:
the memristor according to claim 1 .
22. The device of claim 21 , wherein the device is a neuromorphic device, memory device, or computing device.