Method for manufacture of a CEM device
A method for the manufacture of a correlated electron material device which method comprises forming a conductive substrate and forming a layer of a correlated electron material on the conductive substrate, wherein the forming of the correlated electron material layer comprises: forming a layer of a metal rich transition or other metal compound; and annealing the layer of the metal rich transition or other metal compound in an atmosphere containing a gaseous precursor for an electron-back donating extrinsic ligand capable of occupying an anion vacancy within the transition or other metal compound; wherein the annealing provides that an anion vacancy within the transition or other metal compound is occupied by an electron back-donating extrinsic ligand; and wherein the annealing is carried out at a predetermined temperature and for a predetermined time whereby to activate electron back-donation from a transition or other metal cation to the electron back-donating extrinsic ligand occupying the anion vacancy.
1. A method for manufacture of a correlated electron material device which method comprises forming a conductive substrate and forming a layer of a correlated electron material on the conductive substrate,
wherein the forming of the layer of the correlated electron material comprises:
forming a layer of a metal rich transition or other metal compound, or combination thereof; and
annealing the layer of the metal rich transition or other metal compound, or combination thereof, in a presence of a gaseous precursor for application of an electron back-donating extrinsic ligand capable of occupying an anion vacancy within the metal rich transition or other metal compound, or combination thereof;
wherein the annealing provides that an anion vacancy within the metal rich transition or other metal compound, or combination thereof, is occupied by the electron back-donating extrinsic ligand capable of occupying the anion vacancy; and
wherein the annealing is carried out at an annealing temperature and for an annealing duration to activate an electron back-donation from a transition or other metal cation to the electron back-donating extrinsic ligand capable of occupying the anion vacancy.
2. The method according to claim 1 , wherein the metal rich transition or other metal compound, or combination thereof comprises a non-stoichiometric metal oxide having general formula M x O 1−x or M 1+x O 2 wherein M comprises an alkaline earth metal, a lanthanide, a transition metal or a post-transition metal, or combination thereof.
3. The method according to claim 1 , wherein the metal rich transition or other metal compound, or combination thereof, comprises a non-stoichiometric metal chalcogenide having general formula M x E 1−x or M 1+x E 2 , and wherein M wherein M comprises an alkaline earth metal, a lanthanide, a transition metal or a post-transition metal, or combination thereof, and E comprises sulphur (S), selenium (Se), tellurium (Te) or polonium (Po), or combination thereof.
4. The method according to claim 1 , wherein the metal rich transition or other metal compound, or combination thereof, comprises nickel (II) oxide (NiO), hafnium (IV) oxide (HfO 2 ) or bismuth (III) telluride (Bi 2 Te 3 ) or combination thereof.
5. The method according to claim 1 , wherein the annealing temperature is between 300° C. and 600° C.
6. The method according to claim 1 , wherein the annealing duration is between 30 seconds and 60 minutes.
7. The method according to claim 1 , wherein the gaseous precursor is maintained at a partial pressure of between 0.5 MPa and 1.5 MPa during at least a portion of the annealing.
8. The method according to claim 1 , further comprising forming a conductive overlay on or over the correlated electron material layer.
9. The method according to claim 1 , wherein the forming of the correlated electron material layer provides an area size for the correlated electron material which is less than 90 nm 2 .
10. The method according to claim 1 , wherein the annealing activates the electron back-donation from the transition or other metal cation to an amount of the applied extrinsic ligand present in the correlated electron material layer of at least fifty percent.
11. The method of claim 1 , wherein the annealing temperature is between 350° C. and 500° C.
12. The method of claim 1 , wherein the annealing temperature is between 350° C. and 450° C.
13. The method according to claim 1 , wherein the electron back-donating extrinsic ligand comprises carbonyl (CO), nitrosyl (NO), an isocyanide (RNC where R is H, C 1 -C 6 alkyl or C 6 -C 10 -aryl), an alkene, an alkyne or a phosphine, or combination thereof.
14. The method of claim 13 , wherein the phosphine comprises a trialkyl phosphine, a triaryl phosphine (R 3 P wherein R is H, C 1 -C 6 -alkyl or C 6 -C 10 -aryl) or a triethyl phosphine (PEt 3 ), or a combination thereof.
15. The method according to claim 1 , wherein the electron back-donation from the transition or other metal cation to the electron back-donating extrinsic ligand corresponds to a maximum in a signature peak area associated with a double bond between a metal atom and a ligand atom in a spectrum of the correlated electron material.
16. The method of claim 15 , wherein the spectrum of the correlated electron material comprises a Fourier Transform Infra-Red (FT-IR) spectrum of the correlated electron material.
17. The method of claim 15 , wherein the spectrum of the correlated electron material comprises an X-ray photoelectron emission (XPS) spectrum of the correlated electron material.