Methods for controlling switching characteristics of a correlated electron material device
Methods are disclosed herein for controlling the switching characteristics of correlated electron material (CEM) switching devices. The methods comprise one or more of controlling a density of grain boundaries in the CEM layer, controlling an open pore porosity in the CEM layer and controlling a surface area of exposed surfaces of the CEM layer during the fabrication of the CEM switching devices.
1. A method for controlling switching characteristics of a correlated electron material device comprising a correlated electron material (CEM) layer, which method comprises controlling one or more of:
a density of grain boundaries in the CEM layer;
an open pore porosity in the CEM layer; and/or
a surface area of exposed surfaces of the CEM layer,
wherein the controlling switching characteristics of the CEM device comprises forming the CEM layer on a substrate to provide a polycrystalline CEM thin film layer having a selected density of grain boundaries and/or a selected open pore porosity.
2. The method of claim 1 , wherein the controlling comprises forming the CEM layer by deposition on the substrate wherein: the deposition comprises controlling deposition process conditions to provide the polycrystalline CEM thin film layer to have the selected density of grain boundaries and/or the selected open pore porosity.
3. The method of claim 1 , wherein the controlling comprises further comprises subsequent annealing on the substrate, wherein:
the annealing comprises controlling annealing process conditions to provide the polycrystalline CEM thin film layer to have the selected density of grain boundaries and/or the selected open pore porosity.
4. The method according to claim 1 , wherein the selected density of grain boundaries comprises a selected minimum value and/or the selected open pore porosity comprises a selected minimum value.
5. The method according to claim 1 , wherein the selected open pore porosity is between 0.1% and 20.0%.
6. The method according to claim 1 , providing that the polycrystalline CEM layer has a volume fraction of grains between 50% and 98%.
7. The method according to claim 1 , providing that the polycrystalline CEM thin film layer has an average grain size between 2 nm and 20 nm.
8. The method according to claim 1 , wherein the CEM comprises a metal-containing chemical compound which is doped by an extrinsic ligand for the metal.
9. The method according to claim 8 , wherein the extrinsic ligand comprises an electron back-donating ligand for the metal.
10. The method according to claim 9 , wherein the extrinsic ligand comprises a carbon-containing ligand providing a carbon atom concentration in the CEM thin film layer between 0.1 atom % and 30 atom %.
11. A correlated electron material switching device comprising a correlated electron material (CEM) layer provided on a substrate, wherein the CEM layer comprises polycrystals and further has:
a volume fraction of grains between 50% and 98%;
an average grains size between 5 nm and 20 nm; or
an average open pore porosity between 0.1% and 20.0%, or
a combination thereof.
12. A method for controlling switching characteristics of a correlated electron material device, comprising:
depositing a polycrystalline correlated electron material (CEM) layer on a substrate, the polycrystalline CEM having a first volume fraction of grain boundaries; and
annealing the polycrystalline CEM layer on the substrate to provide a second volume fraction of grain boundaries in the polycrystalline CEM layer that is different from the first volume fraction of grain boundaries in the polycrystalline CEM layer,
wherein the annealing the polycrystalline CEM layer further comprises controlling one or more annealing process conditions so that the second volume fraction of grain boundaries in the polycrystalline CEM layer is a selected volume fraction.
13. The method according to claim 12 , providing that the second volume fraction of grain boundaries in polycrystalline CEM layer is greater than the first volume fraction of grain boundaries in the polycrystalline CEM layer.
14. The method according to claim 12 , wherein the CEM comprises a metal-containing chemical compound which is doped by an extrinsic ligand for the metal.
15. The method according to claim 14 , providing that the polycrystalline CEM layer has a concentration of the extrinsic ligand substantially the same after the annealing as before the annealing.
16. A method for controlling switching characteristics of a correlated electron material device, comprising:
depositing a polycrystalline correlated electron material (CEM) layer on a substrate, the polycrystalline CEM having a first open pore porosity; and
annealing the polycrystalline CEM layer on the substrate to provide a second open pore porosity in the polycrystalline CEM layer that is different from the first open pore porosity in the polycrystalline CEM layer,
wherein the annealing the polycrystalline CEM layer further comprises controlling one or more annealing process conditions so that the second open pore porosity in the polycrystalline CEM layter is a selected open pore porosity.
17. The method according to claim 16 , providing that the second open pore porosity in the polycrystalline CEM layer is higher than the first open pore porosity in the polycrystalline CEM layer.
18. The method according to claim 16 , wherein the CEM comprises a metal-containing chemical compound which is doped by an extrinsic ligand for the metal.
19. The method according to claim 18 , providing that the polycrystalline CEM layer has a concentration of the extrinsic ligand substantially the same after the annealing as before the annealing.