Optoelectronic memory devices

1. A method, comprising:

providing a resistive/reflective region on a substrate, wherein the resistive/reflective region comprises a material having a characteristic of changing the material's reflectance due to a phase change in the material;

sending an electric current through the resistive/reflective region so as to cause a reflectance change in the resistive/reflective region from a first reflectance value to a second reflectance value different from the first reflectance value; and

optically reading the reflectance change in the resistive/reflective region.

2. The method of claim 1 , wherein the material comprises TaN.

3. The method of claim 1 , wherein said sending the electric current through the resistive/reflective region comprises applying a voltage across the resistive/reflective region.

4. The method of claim 3 , wherein the voltage is such that the reflectance of the resistive/reflective region remains at the second reflectance value after the voltage is removed.

5. The method of claim 3 , wherein said optically reading the reflectance change in the resistive/reflective region is performed after the voltage is removed.

6. The method of claim 1 ,

wherein said sending the electric current through the resistive/reflective region comprises maintaining a voltage potential across the resistive/reflective region so as to cause the reflectance change,

wherein the first reflectance value corresponding to no voltage potential is maintained across the resistive/reflective region, and

wherein the second reflectance value corresponding to the voltage potential is maintained across the resistive/reflective region.

7. The method of claim 6 , wherein said voltage potential is such that the reflectance change in the resistive/reflective region is reversible.

8. The method of claim 6 , wherein said optically reading the reflectance change in the resistive/reflective region is performed while said voltage potential is being applied across the resistive/reflective region.

9. The method of claim 1 , wherein said optically reading the reflectance change in the resistive/reflective region comprises:

sending a first incident laser beam to the resistive/reflective region;

receiving a first reflected beam from the resistive/reflective region, wherein the first reflected beam is a result of a reflection of the first incident laser beam off the resistive/reflective region;

sending a second incident laser beam to another reference resistive/reflective region, wherein the another reference resistive/reflective region is essentially identical to the resistive/reflective region;

receiving a second reflected beam from the another reference resistive/reflective region wherein the second reflected beam is a result of a reflection of the second incident laser beam off the another reference resistive/reflective region; and

comparing beam intensities of the first and second reflected beams.

10. A method, comprising:

providing a resistive/reflective region on a substrate, wherein the resistive/reflective region comprises a material having a characteristic of changing the material's resistance due to the material absorbing heat;

projecting a laser beam at a first beam intensity on the resistive/reflective region resulting in the resistive/reflective region changing from a first resistance value to a second resistance value different from the first resistance value;

electrically reading the second resistance value of the resistive/reflective region while the laser beam is being projected on the resistive/reflective region at the first beam intensity,

in response to the second resistance value of the resistive/reflective region being electrically read, determining that an optical signal carried by the laser beam has a first digital value when the second resistance value of the resistive/reflective region is electrically read;

after said electrically reading the second resistance value is performed, projecting the laser beam at a second beam intensity on the resistive/reflective region resulting in the resistive/reflective region changing from the second resistance value to the first resistance value;

electrically reading the first resistance value of the resistive/reflective region while the laser beam is being projected on the resistive/reflective region at the second beam intensity; and

in response to the first resistance value of the resistive/reflective region being electrically read, determining that the optical signal carried by the laser beam has a second digital value different from the first digital value when the first resistance value of the resistive/reflective region is electrically read.

11. The method of claim 10 , wherein the material comprises TaN.

12. The method of claim 10 , wherein the second beam intensity is zero.

13. The method of claim 10 , wherein said electrically reading the second resistance of the resistive/reflective region comprises comparing a first voltage drop across the resistive/reflective region and a second voltage drop across another reference resistive/reflective region, wherein the another reference resistive/reflective region is essentially identical to the resistive/reflective region.