Nonvolatile memory elements having conductive structures with semimetals and/or semiconductors

1. A memory element programmable between different impedance states, comprising:

a first electrode layer comprising a semimetal or semiconductor (semimetal/semiconductor);

a second electrode; and

a switch layer in physical contact with the first and second electrodes and comprising an insulating material, the switch layer configured to create a reversible change in the impedance of the memory element by altering the impedance of conductive regions traversing the insulating material by application of electric fields, the conductive regions comprising semimetal/semiconductor atoms from the first electrode layer; wherein,

the impedance is relatively high in response to application of a voltage having a first polarity with respect to the first and second electrodes, and

the impedance is relatively low in response to application of a voltage having a second polarity with respect to the first and second electrodes.

2. The memory element of claim 1 , wherein:

the semimetal/semiconductor is selected from the group of: carbon (C), tellurium (Te), antimony (Sb), arsenic (As), germanium (Ge), silicon (Si), bismuth (Bi), tin (Sn), sulfur (S), selenium (Se).

3. The memory element of claim 1 , wherein:

the first electrode includes the semimetal/semiconductor in combination with at least one first electrode metal.

4. The memory element of claim 3 , wherein:

the first electrode metal is a transition metal.

5. The memory element of claim 4 , wherein:

the first electrode metal is a rare earth metal.

6. The memory element of claim 3 , wherein:

the first electrode metal is not a transition metal.

7. The memory element of claim 1 , wherein:

the insulating material comprises a metal oxide.

8. The memory element of claim 7 , wherein:

the metal of the metal oxide is a transition metal.

9. The memory element of claim 8 , wherein:

the metal of the metal oxide is a rare earth metal.

10. The memory element of claim 7 , wherein:

the metal of the metal oxide is not a transition metal.

11. The memory element of claim 7 , wherein:

the insulating material is selected from the group of gadolinium oxide, hafnium oxide, tantalum oxide, aluminum oxide, and zirconium oxide in stoichiometric or non-stoichiometric forms.

12. The memory element of claim 1 , wherein:

the first electrode includes the semimetal/semiconductor and an electrode metal; and

the insulating material is a metal oxide of the electrode metal.

13. The memory element of claim 1 , wherein:

the semimetal/semiconductor comprises tellurium;

the first electrode further includes a metal selected from, titanium, zirconium and hafnium; and

the switch layer comprises a metal oxide.