Method of forming Pr

1. A a method of forming Pr X Ca 1-x MnO 3 thin films having a PMO/CMO super lattice structure using metalorganic chemical vapor deposition, comprising:

preparing organometallic compounds and solvents;

mixing organometallic compounds and solvents to form PMO and CMO precursors;

injecting the precursors for PMO and CMO into a MOCVD chamber vaporizer;

selecting deposition parameters to form a nano-sized PCMO thin film or a crystalline PCMO thin film from the injection of PMO and CMO precursors, wherein the PMO and CMO precursors are alternately injected into the MOCVD chamber vaporizer;

maintaining the selected deposition parameters to deposit the PCMO thin film species having a desired Pr:Ca concentration ratio in a specific portion of the PCMO thin film; and

annealing the PCMO thin film at a selected temperature for a selected time period.

2. The method of claim 1 wherein said preparing organometallic compounds includes preparing Pr(thd) 3 Ca(thd) 2 , and Mn(thd) 3 , where thd is C 11 H 19 O 2 .

3. The method of claim 1 wherein said preparing solvents includes preparing organic solvents of butylether and tetraglyme.

4. The method of claim 1 wherein said mixing includes mixing Pr(thd) 3 Ca(thd) 2 , Mn(thd) 3 , in a mixed solvent of butyl ether and tetraglyme in a volume ratio of 3:1, thus forming precursors for PMO and CMO having a molar ratio of about (1:0.5) of Pr:Mn and (1:0.5) of Ca:Mn, respectively.

5. The method of claim 1 wherein said injecting includes injecting the PMO and CMO precursors, alternately into a MOCVD chamber vaporizer at a temperature in a range of between about 240° C. to 280° C., by a liquid flow meter, at a rate of between about 0.2 ml/min to 0.4 ml/min, and maintaining a feed line of the MOCVD chamber at a temperature of between about 250° C. to 280° C.

6. The method of claim 1 wherein said maintaining the selected deposition parameters to deposit the PCMO thin film species includes maintaining the deposition parameters according to the following table:

Process One:

Process

Nano-Sized

Two: Crystallized

PCMO Thin Film

PCMO Thin Film

Deposition Temperature

350° C. to 420° C.

420° C. to 550° C.

Deposition Pressure

1 torr to 5 torr

1 torr to 5 torr

Oxygen Partial Pressure

20% to 30%

20% to 30%

Vaporizer Temperature

200° C. to 240° C.

200° C. to 240° C.

Solution Delivery Rate

0.1 ml/min to 0.5 ml/

0.1 ml/min to 0.5 ml/

min

min

Deposition Time

1 minute to 30 minutes

1 minute to 30 minutes

Annealing

525° C. for 30 minutes

600° C. for 30

minutes.

7. The method of claim 1 which includes injecting PMO as the first precursor into the MOCVD chamber to provide a PCMO thin film having a calcium-poor concentration at the bottom of the PCMO layer to form an RRAM having bipolar switching properties and alternately injecting CMO as the first precursor into the MOCVD chamber to provide a calcium-rich concentration at the bottom and top of the PCMO layer to form an RRAM having mono-polar swtiching properties.

8. A a method of forming Pr X Ca 1-x MnO 3 thin films having a PMO/CMO super lattice structure using metalorganic chemical vapor deposition, comprising:

preparing organometallic compounds and solvents, including preparing Pr(thd) 3 Ca(thd) 2 , and Mn(thd) 3 , where thd is C 11 H 19 O 2 , and preparing organic solvents of butylether and tetraglyme,

mixing organometallic compounds and solvents to form PMO and CMO precursors;

injecting the precursors for PMO and CMO into a MOCVD chamber vaporizer;

selecting deposition parameters to form a nano-sized PCMO thin film or a crystalline PCMO thin film from the injection of PMO and CMO precursors, wherein the PMO and CMO precursors are alternately injected into the MOCVD chamber vaporizer;

maintaining the selected deposition parameters to deposit the PCMO thin film species having a desired Pr:Ca concentration ratio in a specific portion of the PCMO thin film; and

annealing the PCMO thin film at a selected temperature for a selected time period.

9. The method of claim 8 herein said mixing includes mixing Pr(thd) 3 Ca(thd) 2 , Mn(thd) 3 , in a mixed solvent of butyl ether and tetraglyme in a volume ratio of 3:1, thus forming precursors for PMO and CMO having a molar ratio of about (1:0.5) of Pr:Mn and (1:0.5) of Ca:Mn, respectively.

10. The method of claim 8 wherein said injecting includes injecting the PMO and CMO precursors, alternatively into a MOCVD chamber vaporizer at a temperature in a range of between about 240° C. to 280° C., by a liquid flow meter, at a rate of between about 0.2 ml/min to 0.4 ml/min, and maintaining a feed line of the MOCVD chamber at a temperature of between about 250° C. to 280° C.

11. The method of claim 8 wherein said maintaining the selected deposition parameters to deposit the PCMO thin film species maintaining the deposition parameters according to the following table:

Process One:

Process

Nano-Sized

Two: Crystallized

PCMO Thin Film

PCMO Thin Film

Deposition Temperature

350° C. to 420° C.

420° C. to 550° C.

Deposition Pressure

1 torr to 5 torr

1 torr to 5 torr

Oxygen Partial Pressure

20% to 30%

20% to 30%

Vaporizer Temperature

200° C. to 240° C.

200° C. to 240° C.

Solution Delivery Rate

0.1 ml/min to 0.5 ml/

0.1 ml/min to 0.5 ml/

min

min

Deposition Time

1 minute to 30 minutes

1 minute to 30 minutes

Annealing

525° C. for 30 minutes

600° C. for 30

minutes.

12. The method of claim 8 which includes injecting PMO as the first precursor into the MOCVD chamber to provide a PCMO thin film having a calcium-poor concentration at the bottom of the PCMO layer to form an RRAM having bipolar switching properties and alternately injecting CMO as the first precursor into the MOCVD chamber to provide a calcium-rich concentration at the bottom and top of the PCMO layer to form an RRAM having monopolar swtiching properties.

13. A a method of forming Pr X Ca 1-x MnO 3 thin films having a PMO/CMO super lattice structure using metalorganic chemical vapor deposition, comprising:

preparing organometallic compounds and solvents;

mixing organometallic compounds and solvents to form PMO and CMO precursors;

injecting the precursors for PMO and CMO into a MOCVD chamber vaporizer;

selecting deposition parameters to form a nano-sized PCMO thin film or a crystalline PCMO thin film from the injection of PMO and CMO precursors, wherein the PMO and CMO precursors are alternately injected into the MOCVD chamber vaporizer;

maintaining the selected deposition parameters to deposit the PCMO thin film species having a desired Pr:Ca concentration ratio in a specific portion of the PCMO thin film according to the following table:

Process One:

Process

Nano-Sized

Two: Crystallized

PCMO Thin Film

PCMO Thin Film

Deposition Temperature

350° C. to 420° C.

420° C. to 550° C.

Deposition Pressure

1 torr to 5 torr

1 torr to 5 torr

Oxygen Partial Pressure

20% to 30%

20% to 30%

Vaporizer Temperature

200° C. to 240° C.

200° C. to 240° C.

Solution Delivery Rate

0.1 ml/min to 0.5 ml/

0.1 ml/min to 0.5 ml/

min

min

Deposition Time

1 minute to 30 minutes

1 minute to 30 minutes

Annealing

525° C. for 30 minutes

600° C. for 30

minutes.

14. The method of claim 13 wherein said preparing organometallic compounds includes preparing Pr(thd) 3 Ca(thd) 2 , and Mn(thd) 3 , where thd is C 11 H 19 O 2 .

15. The method of claim 13 wherein said preparing solvents includes preparing organic solvents of butylether and tetraglyme.

16. The method of claim 13 wherein said mixing includes mixing Pr(thd) 3 Ca(thd) 2 , Mn(thd) 3 , in a mixed solvent of butyl ether and tetraglyme in a volume ratio of 3:1, thus forming precursors for PMO and CMO having a molar ratio of about (1:0.5) of Pr:Mn and (1:0.5) of Ca:Mn, respectively.

17. The method of claim 13 wherein said injecting includes injecting the PMO and CMO precursors, alternately into a MOCVD chamber vaporizer at a temperature in a range of between about 240° C. to 280° C., by a liquid flow meter, at a rate of between about 0.2 ml/min to 0.4 ml/min, and maintaining a feed line of the MOCVD chamber at a temperature of between about 250° C. to 280° C.

18. The method of claim 13 which includes injecting PMO as the first precursor into the MOCVD chamber to provide a PCMO thin film having a calcium-poor concentration at the bottom of the PCMO layer to form an RRAM having bipolar switching properties and alternately injecting CMO as the first precursor into the MOCVD chamber to provide a calcium-rich concentration at the bottom and top of the PCMO layer to form an RRAM having monopolar swtiching properties.