Variable resistance functional body and storage device
View Patent ↗A variable resistance functional body has an insulator interposed between a first electrode and a second electrode and interposed between a third electrode and a fourth electrode. The insulator contains a plurality of conductive particles. The conductive particles are formed by implanting a substance for forming the conductive particles into the insulator by the negative ion implantation method. The conductive particles are provided so that an electrical resistance between the third electrode and the fourth electrode changes on the basis of a size effect or a change in size between before and after application of a prescribed voltage across the first electrode and the second electrode.
1. A variable resistance functional body, comprising:
an insulator interposed between a first electrode and a second electrode and interposed between a third electrode and a fourth electrode which are provided separately from the first and second electrodes; and
a plurality of conductive particles arranged in the insulator,
wherein the arrangement of conductive particles in the insulator is such that upon applying a voltage across the third electrode and the fourth electrode a resulting current flow from the third electrode to the fourth electrode or vice versa within the insulator between the third electrode and the fourth electrode is changed based on current flow from the first electrode to the second electrode or vice versa due to a prescribed voltage applied across the first electrode and the second electrode.
2. The variable resistance functional body as claimed in claim 1 , wherein
the insulator is formed in a layer form,
the first electrode and the second electrode are placed to hold the insulator from both sides in a thickness direction,
the third electrode and the fourth electrode are placed to hold the insulator from both sides in a layer direction perpendicular to the thickness direction, and
the conductive particles are uniformly distributed in the layer direction of the insulator and distributed within a certain range in the thickness direction of the insulator.
3. The variable resistance functional body as claimed in claim 2 , wherein
a concentration of an element constituting the conductive particles is maximized in a certain position of the insulator and reduced away from the certain position in the thickness direction.
4. The variable resistance functional body as claimed in claim 2 , wherein
a density of the of the conductive particles is maximized in a certain position of the insulator and reduced away from the position in the thickness direction.
5. The variable resistance functional body as claimed in claim 2 , wherein
a particle diameter of the conductive particles is maximized in a certain position of the insulator and reduced away from the position in the thickness direction.
6. The variable resistance functional body as claimed in claim 1 , wherein
the insulator contains the conductive particles having a particle diameter of not smaller than 0.2 nm and smaller than 4 nm.
7. The variable resistance functional body as claimed in claim 1 , wherein
the insulator has a film thickness of not smaller than 2 nm and smaller than 50 nm.
8. The variable resistance functional body as claimed in claim 1 , wherein
at least one of the particles is located between the third and fourth electrodes, and an electrical resistance between the third and fourth electrodes is changed in accordance with an amount of electric charges accumulated in another particle or in accordance with a size change of the at least one of the particles.
9. The variable resistance functional body as claimed in claim 1 , wherein
distribution of particle diameters of the particles is continuously changed in a thickness direction of the insulator.
10. The variable resistance functional body as claimed in claim 9 , wherein
the particle diameter is maximized in a certain position of the insulator in the thickness direction of the insulator and reduced away from the certain position toward both sides of the insulator.
11. The variable resistance functional body as claimed in claim 2 , wherein
the particles contained in the insulator have at least two kinds of particle diameters,
the particles are distributed in the insulator in such a way that the electric charges moving between the third and fourth electrodes move along comparatively large particles, and that the electric charges moving between the first and second electrodes move across comparatively small particles.
12. The variable resistance functional body as claimed in claim 1 , wherein
the particles contained in the insulator have at least two kinds of particle diameters,
a particle diameter of comparatively small particles is not less than 0.2 nm, and
a particle diameter of comparatively large particles is not more than 4 nm.
13. The variable resistance functional body as claimed in claim 1 , wherein
the particles contained in the insulator have at least two kinds of particle diameters,
an average resistance rate per unit volume between the third electrode and the fourth electrode is smaller than an average resistance rate per unit volume between the first electrode and the second electrode.
14. The variable resistance functional body as claimed in claim 1 , wherein
the particles contained in the insulator include comparatively large particles mainly bearing a role of electrical conduction and comparatively small particles mainly bearing a role of retaining electric charge.
15. The variable resistance functional body as claimed in claim 2 , wherein
at least one particle of particles contained in the insulator contacts the third or fourth electrode and at least one other particle contacts none of the first to fourth electrodes.
16. A storage device having a variable resistance functional body, comprising:
an insulator interposed between a first electrode and a second electrode and interposed between a third electrode and a fourth electrode which are provided separately from the first and second electrodes; and
a plurality of conductive particles arranged in the insulator,
wherein the arrangement of conductive particles in the insulator is such that upon applying a voltage across the third electrode and the fourth electrode a resulting current flow from the third electrode to the fourth electrode or vice versa within the insulator between the third electrode and the fourth electrode is changed based on current flow from the first electrode to the second electrode or vice versa due to a prescribed voltage applied across the first electrode and the second electrode.
17. The storage device as claimed in claim 16 , wherein
at least two layers of the variable resistance functional body are stacked in a direction perpendicular to a substrate.