PCMO thin film with memory resistance properties
View Patent ↗A method is provided for forming a Pr 0.3 Ca 0.7 MnO 3 (PCMO) thin film with crystalline structure-related memory resistance properties. The method comprises: forming a PCMO thin film with a first crystalline structure; and, changing the resistance state of the PCMO film using pulse polarities responsive to the first crystalline structure. In one aspect the first crystalline structure is either amorphous or a weak-crystalline. Then, the resistance state of the PCMO film is changed in response to unipolar pulses. In another aspect, the PCMO thin film has either a polycrystalline structure. Then, the resistance state of the PCMO film changes in response to bipolar pulses.
1. A method for forming a Pr 0.3 Ca 0.7 MnO 3 (PCMO) thin film with crystalline structure-related memory resistance properties, the method comprising:
depositing a PCMO thin film using a deposition process selected from a group consisting of a metal organic chemical vapor deposition (MOCVD) process, spin-coating, and MOCVD followed by spin-coating:
forming a PCMO thin film with a first crystalline structure selected from a group including amorphous, weak-crystalline, and polycrystalline; and,
changing the resistance state of the PCMO film using pulse polarities responsive to the first crystalline structure.
2. The method of claim 1 wherein forming a PCMO thin film with a first crystalline structure includes forming a PCMO thin film with a first crystalline structure selected from the group including amorphous and weak-crystalline; and,
wherein changing the resistance state of the PCMO film using pulse polarities responsive to the first crystalline structure includes changing the resistance state of the PCMO film in response to unipolar pulses.
3. The method of claim 2 wherein changing the resistance state of the PCMO film in response to unipolar pulses includes:
writing a high resistance state in response to a pulse having an amplitude in the range of 2 to 10 volts (V), and a pulse duration of in the range of 10 to 1000 nanoseconds (ns); and,
resetting to a low resistance state in response to a pulse having an amplitude in the range of 2 to 5V, and a pulse duration in the range of 1.5 microseconds (μs) to 10 milliseconds (ms).
4. The method of claim 3 wherein writing a high resistance state includes writing a resistance in the range of about 60 kilo-ohms (k-ohms) to 10 megaohms; and,
wherein resetting to a low resistance state includes resetting to a resistance in the range of about 0.5 to 50 k-ohms.
5. The method of claim 3 wherein forming a PCMO thin film with a first crystalline structure includes forming a PCMO film with an amorphous crystalline structure:
wherein writing a high resistance state includes writing a resistance of greater than about 60 k-ohms, using a 5 V pulse of 100 ns: and,
wherein resetting to a low resistance state includes resetting to a resistance of less than about 50 k-ohms, using a 3 V pulse of 10 μs.
6. The method of claim 4 wherein forming a PCMO thin film with a first crystalline structure includes forming a PCMO film with a weak-crystalline crystalline structure;
wherein writing a high resistance state includes writing a resistance of greater than about 60 k-ohms, using a 5 V pulse of 100 ns: and,
wherein resetting to a low resistance state includes resetting to a resistance of less than about 50 k-ohms using a 3 V pulse of 10 μs.
7. The method of claim 1 wherein depositing PCMO by MOCVD followed by spin-coating:
MOCVD depositing a seed layer of PCMO having a thickness of about 200 Å; and,
spin-coating a plurality of PCMO layers, having a combined thickness of about 2500 Å, overlying the seed layer.
8. The method of claim 1 wherein forming a PCMO thin film with a first crystalline structure includes forming a PCMO thin film with a polycrystalline crystalline structure; and,
wherein changing the resistance state of the PCMO film using pulse polarities responsive to the first crystalline structure includes changing the resistance state of the PCMO film in response to bipolar pulses.
9. The method of claim 8 wherein changing the resistance state of the PCMO film in response to bipolar pulses includes:
writing a high resistance state in response to a pulse having an amplitude of 5 volts (V), or less, and a pulse duration of 1 ms, or less: and,
resetting to a low resistance state in response to a pulse having an amplitude of −5 V, or greater, and a pulse duration of 1 ms, or less.
10. The method of claim 9 wherein writing a high resistance state includes writing a resistance of greater than about 300 k-ohms; and,
wherein resetting to a low resistance state includes resetting to a resistance of less than about 5 k-ohms.
11. The method of claim 10 wherein depositing a PCMO thin film includes depositing PCMO, having a thickness of about 2000 Å, using a MOCVD process.
12. A method for forming a Pr 0.3 Ca 0.7 MnO 3 (PCMO) thin film with crystalline structure-related memory resistance properties, the method comprising:
using a deposition process selected from a group consisting of a metal organic chemical vapor deposition (MOCVD) process, spin-coating, and MOCVD followed by spin-coating, forming a PCMO thin film with a crystalline structure;
in response to a PCMO crystalline structure selected from the group consisting of amorphous and weak-crystalline, using a unipolar pulse to change PCMO resistance states; and,
in response to a PCMO polycrystalline structure, using a bipolar pulse to change PCMO resistance states.