Nonvolatile memory device including two-dimensional material and apparatus including the nonvolatile memory device

1. A nonvolatile memory device comprising:

a channel element;

a source and a drain electrically each connected to the channel element. the source and the drain being spaced apart from each other;

a gate electrode facing the channel element;

a storage stack between the channel element and the gate electrode,

the storage stack including a plurality of charge storage layers spaced apart from each other from the channel element towards the gate electrode,

each of the plurality of charge storage layers including a 2-dimensional (2D) material; and

a channel barrier layer between the channel element and the storage stack,

wherein

the nonvolatile memory device is configured to have a multi-bit memory characteristic due to the plurality of charge storage layers,

the storage stack further includes a plurality of interlayer barrier layers alternately provided between the plurality of charge storage layers such that,

each corresponding interlayer barrier layer among the plurality of interlayer barrier layers is between two adjacent charge storage layers among the plurality of charge storage layers, and

each corresponding charge storage layer among the plurality of charge storage layers is between two adjacent interlayer barrier layers among the plurality of interlayer barrier layers,

the plurality of interlayer barrier layers comprise a material having an energy band gap,

the plurality of interlayer barrier layers include a 2D semiconductor or a 2D insulator, and

thicknesses of the plurality of interlayer barrier layers decrease from the channel element towards the gate electrode,

wherein thicknesses of the plurality of charge storage layers increase from the channel element towards the gate electrode.

2. The nonvolatile memory device of claim 1 , wherein the plurality of charge storage layers are spaced apart from each other respectively at intervals that decrease from the channel element towards the gate electrode.

3. The nonvolatile memory device of claim 1 , further comprising:

a gate insulating layer between the storage stack and the gate electrode.

4. The nonvolatile memory device of claim 1 , the multi-bit memory characteristic of the nonvolatile memory device is 3-bit or more.

5. The nonvolatile memory device of claim 1 , where the nonvolatile memory device has a vertical-NAND memory structure.

6. A synapse device comprising:

the nonvolatile memory device of claim 1 .

7. The synapse device of claim 6 , wherein

the synapse device includes a pre-synaptic neuron circuit and a post-synaptic neuron circuit,

the gate electrode of the nonvolatile memory device is connected to the pre-synaptic neuron circuit, and

the source of the nonvolatile memory device is connected to the post-synaptic neuron circuit.

8. The synapse device of claim 6 , further comprising:

a plurality of nonvolatile memory devices, wherein

the plurality of nonvolatile memory devices include the nonvolatile memory device and other nonvolatile memory devices corresponding to the nonvolatile memory device, wherein

the plurality of nonvolatile memory devices are arranged in a plurality of rows and a plurality of columns.

9. The synapse device of claim 8 , further comprising:

a plurality of first wirings; and

a plurality of second wirings crossing the plurality of first wirings,

wherein the plurality of nonvolatile memory devices are respectively located at intersections of the plurality of first wirings and the plurality of second wirings.

10. The synapse device of claim 9 , wherein

the synapse device includes a pre-synaptic neuron circuit and a post-synaptic neuron circuit,

the plurality of first wirings are connected to the pre-synaptic neuron circuit, and

the plurality of second wirings are connected to the post-synaptic neuron circuit.

11. A neuromorphic device comprising:

the synapse device of claim 6 .

12. The nonvolatile memory device of claim 1 , wherein the plurality of interlayer barrier layers include the 2D semiconductor.

13. The nonvolatile memory device of claim 1 , the plurality of interlayer barrier layers include a transition metal dichalcogenide (TMDC) material as the 2D semiconductor.

14. The nonvolatile memory device of claim 1 , wherein the plurality of interlayer barrier layers include the 2D insulator.

15. The nonvolatile memory device of claim 1 , the plurality of interlayer barrier layers include h-BN as the 2D insulator.

16. The nonvolatile memory device of claim 1 , wherein

the gate electrode is over the channel element.

17. The nonvolatile memory device of claim 16 , further comprising:

a substrate, wherein

the channel element is a region in the substrate between the source and the drain.

18. The nonvolatile memory device of claim 16 , further comprising:

a substrate, wherein

the channel element is a channel layer on the substrate.

19. The nonvolatile memory device of claim 1 , wherein the 2D material includes graphene.

20. The nonvolatile memory device of claim 19 , wherein each of the plurality of charge storage layers includes 1 to 20 layers of graphene.

21. The nonvolatile memory device of claim 1 , wherein a dielectric constant of a material of the channel barrier layer is smaller than a dielectric constant of a material of the plurality of interlayer barrier layers in the storage stack.

22. The nonvolatile memory device, of claim 1 , wherein the channel barrier layer has a dielectric constant of 6 or higher.

23. The nonvolatile memory device of claim 1 , wherein a thickness of the channel barrier layer is greater than a thickness of the interlayer barrier layer.