Formation of correlated electron material (CEM) device via dopant deposition and anneal
Subject matter disclosed herein may relate to fabrication of a correlated electron material (CEM) switch. In particular embodiments, formation of a CEM switch may comprise depositing metal layers, such layers of a transition metal, over a conductive substrate. Dopant layers may subsequently be deposited on the layers of the transition metal, followed by annealing of the layers of transition metal and dopant layers. Responsive to annealing, dopant from the dopant layers may diffuse into the one or more layers of transition metal, thereby forming a CEM.
1. A method of constructing a switching device, comprising:
depositing in a chamber one or more first layers of a first material having an atomic concentration of a first transition metal of at least about 90.0% over a conductive substrate;
depositing one or more second layers of a second material comprising an atomic concentration of carbon of at least about 90.0% over the one or more layers of the first material; and
annealing the one or more second layers of the second material deposited over the one or more first layers in an oxygen-containing environment, the annealing to diffuse carbon and oxygen into the one or more first layers to form a first correlated electron material (CEM), wherein the one or more second layers are deposited to a particular thickness selected to impart an approximate specified atomic concentration of carbon in at least a portion of the one or more first layers from the annealing.
2. The method of claim 1 , wherein the first CEM comprises an atomic concentration of between about 0.1% and about 15.0% of carbon.
3. The method of claim 1 , further comprising forming the oxygen-containing environment via substantially filling the chamber with carbon dioxide (CO 2 ), carbon monoxide (CO), oxygen (O 2 ), ozone (O 3 + ) or nitrosyl (NO), or any combination thereof.
4. The method of claim 1 , further comprising, prior to the annealing, depositing one or more capping layers over the one or more second layers.
5. The method of claim 4 , further comprising:
confining, during the annealing, the diffused carbon to within the one or more first layers.
6. The method of claim 1 , further comprising, during the annealing, exposing the one or more second layers deposited over the one or more first layers to an ambient temperature of between about 350.0° C. and about 450.0° C.
7. The method of claim 1 , further comprising etching one or more voids into the one or more first layers prior to depositing the one or more second layers over the one or more first layers.
8. The method of claim 7 , further comprising:
depositing, prior to the annealing, one or more third layers of a third material comprising an atomic concentration of a second transition metal of at least 90.0% over the one or more second layers;
depositing, prior to the annealing, one or more fourth layers of a material comprising an atomic concentration of carbon over the one or more third layers; and
diffusing, via the annealing, carbon and oxygen into the one or more third layers to form a second CEM having an atomic concentration of between about 0.1% and about 15.0% of carbon.
9. The method of claim 8 , wherein the second CEM corresponds to a localized region comprising an atomic concentration of carbon that is at least 20.0% greater than an atomic concentration of carbon at a localized region corresponding to the first CEM.
10. The method of claim 8 , wherein the first transition metal comprises the same metallic species as the second transition metal.
11. The method of claim 8 , wherein the first transition metal comprises a metallic species different from a metallic species of the second transition metal.
12. A method of constructing a switching device, comprising:
depositing, in a chamber, one or more first layers of a first material having an atomic concentration of a first transition metal of at least about 90.0% over a conductive substrate;
forming one or more voids in the one or more first layers of the first material;
depositing one or more second layers of a second material having an atomic concentration of carbon of at least about 90.0% over the one or more first layers of the first material; and
annealing the one or more second layers deposited over the one or more first layers in an oxygen-containing environment, the annealing to diffuse carbon and oxygen into the one or more first layers to form a correlated electron material (CEM).
13. The method of claim 12 , further comprising:
prior to forming the one or more voids, depositing an insulative material over the one or more first layers; and
prior to forming the one or more voids, depositing one or more third layers of a third material comprising an atomic concentration of a second transition metal of at least 90.0% over the insulative material.
14. The method of claim 12 , wherein forming the one or more voids comprises etching the one or more first layers of the first material to form the one or more voids in the one or more layers of the first material.
15. The method of claim 12 , wherein the CEM comprises an atomic concentration of carbon of between about 0.1% to about 15.0%.
16. The method of claim 12 , further comprising forming the oxygen-containing environment via substantially filling the chamber with carbon dioxide (CO 2 ), carbon monoxide (CO), oxygen (O 2 ) ozone (O 3 + ) or nitrosyl (NOCl), or any combination thereof.
17. The method of claim 12 , further comprising evaporating excess carbon from a surface of the CEM after the annealing of the one or more second layers of the second material deposited over the one or more first layers of the first material.
18. The method of claim 12 , further comprising during the annealing, exposing the one or more second layers of the second material deposited on the one or more first layers of the first material, to a temperature of between about 350.0° C. and about 450.0° C.
19. The method of claim 12 , further comprising inhibiting evaporation of carbon from the one or more first layers of the first material during the annealing of the one or more second layers of the second material deposited over the one or more first layers of the first material.
20. The method of claim 19 , further comprising depositing a capping layer over the second one or more layers of the second material, prior to the annealing, to bring about inhibiting of evaporation of the second material from the one or more first layers of the first material.
21. A switching device, comprising:
a structure comprising two or more first layers of a first transition metal oxide, a first transition metal or a first transition metal compound, or a combination thereof, the two or more first layers being separated by insulating material, the structure comprising a void exposing first doped localized regions of correlated electron material (CEM) formed in the two or more first layers, the first doped localized regions of CEM being in contact with an electrode material disposed in the void.
22. The switching device of claim 21 , wherein the first doped localized regions comprise an atomic concentration of between about 0.1% and about 5.0% of carbon.
23. The switching device of claim 21 , wherein the structure further comprises one or more second layers of a second transition metal oxide, a second transition metal or a second transition metal compound, or a combination thereof, the void further exposing second doped localized regions of CEM formed in the one or more second layers, the second doped localized regions of CEM being in contact with the electrode material disposed in the void.
24. The switching device of claim 23 , wherein the second doped localized regions of CEM comprise an atomic concentration of carbon that is at least 20.0% greater than the atomic concentration of carbon of the first doped localized regions of CEM.