Devices and apparatuses including asymmetric ferroelectric materials, and related methods
Methods of operating a ferroelectric memory cell. The method includes applying one of a positive bias voltage and a negative bias voltage to a ferroelectric memory cell having a capacitor including a top electrode, a bottom electrode, a ferroelectric material between the top electrode and the bottom electrode, and an interfacial material between the ferroelectric material and one of the top electrode and the bottom electrode. Another of the positive bias voltage and the negative bias voltage is applied to the ferroelectric memory cell to switch a polarization of the ferroelectric memory cell, wherein an absolute value of the negative bias voltage is different from an absolute value of the positive bias voltage. Related ferroelectric memory cells include a ferroelectric material exhibiting asymmetric switching properties.
1. A device, comprising:
a ferroelectric material adjacent a first electrode, wherein the ferroelectric material is configured to exhibit asymmetric switching properties;
a second electrode adjacent the ferroelectric material opposite the first electrode; and
an interfacial material between the ferroelectric material and one of the first electrode and the second electrode.
2. The device of claim 1 , wherein the ferroelectric material comprises hafnium oxide, zirconium oxide, lead zirconate titanate, or combinations thereof.
3. The device of claim 1 , wherein the ferroelectric material has a thickness of about 70 Å.
4. The device of claim 1 , wherein the interfacial material has a thickness of from about 2 Å to about 5 Å.
5. The device of claim 1 , wherein the interfacial material comprises an oxide of a material of the first electrode.
6. The device of claim 5 , wherein the first electrode comprises titanium nitride, titanium aluminum nitride, tantalum nitride, platinum, or combinations thereof.
7. The device of claim 1 , wherein the ferroelectric material is doped with silicon, aluminum, zirconium, magnesium, strontium, gadolinium, yttrium, or combinations thereof.
8. An apparatus, comprising:
a memory device, comprising:
an asymmetric ferroelectric material configured to switch from a first polarization to a second polarization responsive to exposure to a positive bias voltage having a different magnitude than a negative bias voltage used to switch the asymmetric ferroelectric material from the second polarization to the first polarization.
9. The apparatus of claim 8 , wherein the memory device is configured such that the positive bias voltage and the negative bias voltage are altered after a predetermined number of cycles.
10. The apparatus of claim 8 , wherein the asymmetric ferroelectric material comprises hafnium oxide, zirconium oxide, lead zirconate titanate, or combinations thereof.
11. The apparatus of claim 8 , wherein the memory device further comprises a first electrode on a first side of the asymmetric ferroelectric material and a second electrode on a second side of the asymmetric ferroelectric material.
12. The apparatus of claim 11 , further comprising an interfacial material between the first electrode and the asymmetric ferroelectric material.
13. The apparatus of claim 12 , further comprising another interfacial material between the second electrode and the asymmetric ferroelectric material.
14. The apparatus of claim 13 , wherein the another interfacial material comprises a different material than the interfacial material or has a different thickness than the interfacial material.
15. The apparatus of claim 8 , wherein the asymmetric ferroelectric material is doped with one or more of silicon, aluminum, or magnesium.
16. A method, comprising:
applying one of a positive bias voltage and a negative bias voltage having a different absolute value than the positive bias voltage to an asymmetric ferroelectric material exhibiting asymmetric switching properties; and
applying, to the asymmetric ferroelectric material, another of the positive bias voltage and the negative bias voltage to switch a polarization state of the asymmetric ferroelectric material.
17. The method of claim 16 , further comprising altering at least one of the positive bias voltage or the negative bias voltage during an operating life of a ferroelectric memory cell comprising the asymmetric ferroelectric material.
18. The method of claim 17 , wherein altering at least one of the positive bias voltage or the negative bias voltage during an operating life of a ferroelectric memory cell associated with the asymmetric ferroelectric material comprises altering at least one of the positive bias voltage or the negative bias voltage after a predetermined number of cycles.
19. The method of claim 16 , wherein applying a positive bias voltage to an asymmetric ferroelectric material comprises applying a positive bias voltage to an asymmetric material comprising hafnium oxide, zirconium oxide, lead zirconate titanate, or combinations thereof.
20. The method of claim 16 , wherein:
applying a positive bias voltage comprises applying a positive bias voltage of about 1.8 V; and
applying a negative bias voltage comprises applying a negative bias voltage of about −1.2 V.