Electrochemical random access memory device with contact layer as a heat source
Technologies related to an electrochemical random access memory (ECRAM) device are described herein. The ECRAM device includes a channel layer, an electrolyte layer, a reservoir layer, and a conductive contact layer, where the conductive contact layer is in contact with the reservoir layer. A voltage source is coupled to the contact layer and is configured to cause current to flow laterally across the contact layer from one side to another, resulting in the contact layer emitting heat by way of Joule heating. When the ECRAM device is heated to a sufficiently high temperature, a second voltage is applied across the stack of layers, thereby causing ion transport between the reservoir layer and the channel layer.
1. A system comprising:
an electrochemical random access memory (ECRAM) device comprising:
an ionic reservoir layer that comprises an oxygen vacancy;
an electrolyte layer in contact with the ionic reservoir layer;
a channel layer in contact with the electrolyte layer such that the electrolyte layer is positioned between the ionic reservoir layer and the channel layer; and
a contact layer in contact with the ionic reservoir layer such that the ionic reservoir layer is positioned between the contact layer and the electrolyte layer;
a first voltage source in electrical contact with the contact layer, where the first voltage source is configured to apply a first voltage across the contact layer such that current travels laterally across the contact layer and the contact layer emits heat by way of Joule heating; and
a second voltage source in electrical contact with the contact layer and a contact that is coupled to the channel layer, where the second voltage source is configured to apply a second voltage across the ionic reservoir layer, the electrolyte layer, and the channel layer, and further where the heat emitted by the contact layer facilitates transition of the oxygen vacancy from the ionic reservoir layer to the channel layer by way of the electrolyte layer when the second voltage is applied across the ionic reservoir layer, the electrolyte layer, and the channel layer.
2. The system of claim 1 , wherein the contact layer is at least partially formed of tungsten.
3. The system of claim 1 , where the contact is a drain contact of the ECRAM, the ECRAM device further comprises:
a source contact coupled to the channel layer, where the contact layer comprises a first terminal and a second terminal, where ionic current flows between the first terminal and the drain contact by way of the ionic reservoir layer, the electrolyte layer, and the channel layer based upon the second voltage applied across the ionic reservoir layer, the electrolyte layer, and the channel layer, and further where the current travels between the first contact terminal and the second contact terminal based upon the first voltage applied across the contact layer.
4. The system of claim 3 , further comprising readout circuitry that is coupled to at least one of the source contact or the drain contact, where the readout circuitry is configured to readout a state of the channel layer.
5. The system of claim 1 , further comprising a dielectric layer placed in contact with the contact layer such that the contact layer is between the dielectric layer and the ionic reservoir layer.
6. The system of claim 1 , where the channel layer comprises vanadium dioxide (VO 2 ).
7. The system of claim 6 , where the channel layer comprises VO 2 alloyed with at least one of titanium, aluminum, gallium, or indium.
8. The system of claim 1 , where the channel layer comprises niobium dioxide (NbO 2 ).
9. The system of claim 1 , where the channel layer comprises a rare earth perovskite material having a composition of RiNiO 3 , where R is one of samarium (Sm), praseodymium (Pr), or neodymium (Nd).
10. The system of claim 1 , where the ionic reservoir layer and the channel layer are formed of a transition metal oxide.
11. The system of claim 1 , where a conductance of the channel layer is indicative of a weight that is applied to a node or synapse of an artificial neural network (ANN), and further where the system is configured to output a value based upon the conductance of the channel.
12. The system of claim 1 , where the contact layer comprises platinum.
13. The system of claim 1 , where the first voltage source applies the first voltage across the contact layer simultaneously with the second voltage source applying the second voltage across the ionic reservoir layer, the electrolyte layer, and the channel layer.
14. The system of claim 1 , where the first voltage source applies the first voltage across the contact layer prior to the second voltage source applying the second voltage across the ionic reservoir layer, the electrolyte layer, and the channel layer.
15. A method for programming an electrochemical random access memory (ECRAM) device, the method comprising:
applying a first voltage across a contact layer of the ECRAM device, thereby causing the contact layer of the ECRAM to emit heat, where the contact layer is in contact with an ionic reservoir layer of the ECRAM device; and
applying a second voltage across the ionic reservoir layer and a channel layer of the ECRAM device, thereby causing an ion to travel from the ionic reservoir layer to the channel layer through an electrolyte layer, where the electrolyte layer is positioned between the ionic reservoir layer and the channel layer, where the ECRAM is programmed based upon the ion being placed in the channel layer.
16. The method of claim 15 , where the first voltage is applied prior to the second voltage.
17. The method of claim 15 , where the first voltage is applied simultaneously with the second voltage.
18. The method of claim 15 , where the ion is an oxygen vacancy.
19. The method of claim 15 , where the ionic reservoir layer and the channel layer are formed of a transition metal oxide.
20. A method for creating an electrochemical random access memory (ECRAM) device, the method comprising:
depositing a channel layer on a substrate;
depositing an electrolyte layer on the channel layer, such that the channel layer is positioned between the substrate and the electrolyte layer;
depositing an ionic reservoir layer on the electrolyte layer, such that the electrolyte layer is positioned between the channel layer and the ionic reservoir layer;
depositing a conductive contact layer on the ionic reservoir layer, such that the ionic reservoir layer is positioned between the electrolyte layer and the conductive contact layer;
forming an electrical contact that is coupled to the channel layer;
electrically coupling a first voltage source to a first side of the contact layer and a second side of the contact layer, where the first voltage source is configured to apply a first voltage laterally across the contact layer between the first side and the second side thereby causing the contact layer to emit heat; and
electrically coupling a second voltage source to the contact layer and the electrical contact that is coupled to the channel layer, where the second voltage source is configured to apply a second voltage across the ionic reservoir layer, the electrolyte layer, and the channel layer to facilitate transition of an oxygen vacancy from the ionic reservoir layer to the channel layer.